PATENT DOCUMENT

Publication Number: US-8884939-B2
Application Number: US-89528510-A
Country: US
Kind Code: B2

Title: Display brightness control based on ambient light levels

Abstract:
Methods and devices are provided for controlling the brightness of a display for an electronic device based on ambient light conditions. In one embodiment, an electronic device may employ one or more brightness adjustment profiles for changing the brightness of a display based on the ambient light level. The brightness adjustment profiles may include two or more sections, each corresponding to different ambient light levels, which may be adjusted independently of one another. The different sections may allow a user to customize brightness adjustments for different ambient light conditions. In certain embodiments, the slope and/or offset of a section may be adjusted in response to receiving a user input that changes the brightness setting for a certain ambient light level.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a display comprising a backlight; 
 one or more ambient light sensors configured to detect an ambient light level; 
 a user interface configured to receive a user input that specifies a reflectivity setting for the backlight; and 
 a display controller configured to adjust a slope of a brightness adjustment profile for the backlight based on the reflectivity setting, wherein the brightness adjustment profile identifies brightness levels for the backlight based on the ambient light level and wherein the slope defines a brightness response as the ambient light level changes. 
 
     
     
       2. The electronic device of  claim 1 , wherein the user interface is configured to receive another user input that specifies a lamp brightness setting for the backlight, and wherein the display controller is configured to adjust an offset of the brightness adjustment profile for the backlight based on the lamp brightness setting. 
     
     
       3. The electronic device of  claim 2 , wherein the user interface comprises a first graphical element for receiving the reflectivity setting and a separate second graphical element for receiving the lamp brightness setting. 
     
     
       4. The electronic device of  claim 1 , wherein the user input specifies a brightness setting for the backlight, and wherein the display controller is configured to adjust an offset of the brightness adjustment profile based on the brightness setting. 
     
     
       5. The electronic device of  claim 1 , wherein the user interfaces comprises a graphical element manipulatable by a user to specify both the reflectivity setting and the brightness setting. 
     
     
       6. An electronic device, comprising:
 a display comprising a backlight; 
 one or more ambient light sensors configured to detect an ambient light level; 
 a user interface configured to receive a user input that specifies a brightness setting for the backlight at the detected ambient light level; and 
 a display controller configured to adjust a slope of at least a section of a brightness adjustment profile for the backlight until the brightness setting and a previously identified transition point on the brightness adjustment profile both intersect the brightness adjustment profile; 
 wherein the slope defines a brightness response as the ambient light level changes. 
 
     
     
       7. The electronic device of  claim 6 , wherein the brightness adjustment profile identifies brightness levels for the backlight based on the ambient light level. 
     
     
       8. The electronic device of  claim 6 , wherein the previously identified transition point comprises a previously specified brightness setting for the backlight. 
     
     
       9. The electronic device of  claim 6 , wherein the display controller is configured to adjust the backlight to a brightness level corresponding to the brightness setting. 
     
     
       10. The electronic device of  claim 9 , wherein the user interface is capable of receiving an additional user input that specifies an adjustment rate for the backlight, and wherein the display controller is configured to adjust the backlight to the brightness level at the specified adjustment rate. 
     
     
       11. The electronic device of  claim 6 , wherein the display controller is configured to select the section from a first portion of the brightness adjustment profile that specifies first brightness levels for a first range of ambient light levels and a second portion of the brightness adjustment profile that specifies second brightness levels for a second range of ambient light levels different from the first range. 
     
     
       12. The electronic device of  claim 11 , wherein the display controller is configured to modify the first and second portions independently of one another. 
     
     
       13. A method, comprising:
 receiving a user input that identifies a brightness setting for a backlight; 
 detecting an ambient light level in response to receiving the user input; 
 determining a section of a brightness adjustment profile for a backlight, wherein the section includes the detected ambient light level; and 
 adjusting a slope of at least the section of the brightness adjustment profile to produce a modified brightness adjustment profile that intersects the brightness setting or a threshold value at the detected ambient light level and that intersects a previously specified brightness level on the brightness adjustment profile; 
 wherein the slope defines a brightness response as the ambient light level changes. 
 
     
     
       14. The method of  claim 13 , wherein determining a section of a brightness adjustment profile comprises determining whether the detected ambient light level is above or below an ambient light threshold. 
     
     
       15. The method of  claim 13 , comprising selecting the previously specified brightness level from a plurality of previously specified brightness levels, wherein the previously specified brightness level is on an opposite side of the ambient light threshold from the detected ambient light level. 
     
     
       16. The method of  claim 13 , comprising determining whether the brightness setting exceeds the threshold value, wherein adjusting the slope of the section of the brightness adjustment profile comprises adjusting the slope until the brightness adjustment profile intersects the threshold value if the brightness setting exceeds the threshold level and adjusting the slope until the brightness adjustment profile intersects the brightness setting if the brightness setting does not exceed the threshold value. 
     
     
       17. The method of  claim 13 , comprising determining whether the brightness setting exceeds the threshold value, wherein adjusting the slope comprises setting the slope to zero if the brightness setting exceeds the threshold value. 
     
     
       18. The method of  claim 13 , comprising adjusting a brightness of the backlight based on the modified adjustment profile. 
     
     
       19. Non-transitory computer-readable storage media comprising instructions for:
 determining a section of a brightness adjustment profile for a backlight based on an ambient light level detected upon receipt of a new brightness setting for the backlight, wherein the section includes the detected ambient light level; 
 selecting a transition point on the brightness adjustment profile, wherein the transition point is on an opposite side of an ambient light threshold from the detected ambient light level; and 
 adjusting a slope of at least the section of the brightness adjustment profile to produce a modified brightness adjustment profile that intersects the new brightness setting and the transition point; 
 wherein the slope defines a brightness response as the ambient light level changes. 
 
     
     
       20. The non-transitory computer-readable storage media of  claim 19 , comprising instructions for determining that a portion of the modified adjustment profile is above a maximum brightness level or below a minimum brightness level and clipping the portion of the modified adjustment profile to approach or equal the maximum brightness level or the minimum brightness level. 
     
     
       21. The non-transitory computer-readable storage media of  claim 19 , comprising instructions for determining that the adjusted slope is greater than a maximum slope or less than a minimum slope and modifying the adjusted slope to equal the maximum slope or the minimum slope. 
     
     
       22. A method comprising:
 receiving a user input that identifies a brightness setting for a backlight; 
 detecting an ambient light level in response to receiving the user input; 
 determining a transition point on the brightness adjustment profile, wherein the transition point is on an opposite side of an ambient light threshold from the detected ambient light level; and 
 adjusting a slope of the brightness adjustment profile to produce a modified brightness adjustment profile that intersects the brightness setting and the transition point; 
 wherein the slope defines a brightness response as the ambient light level changes. 
 
     
     
       23. The method of  claim 22 , wherein adjusting a slope of the brightness adjustment profile comprises adjusting the slope for a section of the brightness profile that includes the detected ambient light level. 
     
     
       24. The method of  claim 22 , comprising
 determining that the adjusted slope is greater than a maximum slope or less than a minimum slope; and 
 setting the slope of the brightness adjustment profile to the maximum slope or the minimum slope. 
 
     
     
       25. The method of  claim 24 , wherein setting the slope of the brightness adjustment profile to the maximum slope or the minimum slope comprises adjusting a brightness level for the transition point to produce the maximum slope or the minimum slope.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Provisional Application Ser. No. 61/367,810, filed Jul. 26, 2010, entitled “DISPLAY BRIGHTNESS CONTROL BASED ON AMBIENT LIGHT CONDITIONS,” which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to backlights for displays and, more particularly, to brightness control of backlights based on ambient light conditions. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Electronic devices increasingly include display screens as part of the user interface of the device. As may be appreciated, display screens may be employed in a wide array of devices, including desktop computer systems, notebook computers, and handheld computing devices, as well as various consumer products, such as cellular phones and portable media players. Electronic devices also may include backlights that illuminate the display screens. Ambient light may reflect off the surface of display screens and may reduce the display contrast, thereby making it difficult to view the display screens in high ambient light conditions. Accordingly, as ambient light conditions change, the brightness of a backlight also may be changed to provide sufficient contrast between the ambient light and the backlight. However, the amount of contrast desired between the ambient light and the backlight may vary depending on factors such as user preferences and ambient light conditions. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     The present disclosure generally relates to techniques for controlling the brightness of displays based on ambient light conditions. In accordance with one disclosed embodiment, an electronic device may include one or more ambient light sensors that detect ambient light conditions, such as the ambient light level. The electronic device also may include a display controller that adjusts the brightness of a backlight for the display based on the ambient light conditions. The display controller may adjust the brightness using one or more adjustment profiles that define brightness levels corresponding to different ambient light conditions. According to certain embodiments, the slope of the adjustment profiles may be changed in response to receiving a user input that adjusts display brightness. Further, in certain embodiments, the adjustment profiles may contain two or more sections, each corresponding to different ambient light levels. The slope of each section may be modified independently of the other sections to allow different brightness responses to be employed in different ambient light levels. In certain embodiments, the slope and/or offset of a section may be adjusted by the display controller in response to receiving a user input that changes a brightness setting at a certain ambient light level. 
     The adjustment profiles also may define the rate at which the brightness is adjusted based on the magnitude and/or direction of the change in the ambient light conditions. In certain embodiments, the rate of adjustment may be designed to approximate the physical response of the human vision system. Further, in certain embodiments, noise reduction techniques may be employed by adjusting the response rates based on the magnitude of the change in the ambient light condition and/or based on whether the display is operating at steady state or executing a brightness adjustment. 
     The electronic device further may be designed to vary brightness levels based on the angle of incidence of one or more ambient light sources. For example, in certain embodiments, the ambient light sensor may be designed to perceive the ambient light level differently based on the angle of incidence of a light source. The perceived ambient light level may then be used to adjust the display brightness based on the one or more brightness adjustment profiles. In other embodiments, the ambient light sensor may be designed to detect the angle of incidence of an ambient light source. In these embodiments, the detected angle and the ambient light level may be used to adjust the display brightness. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a block diagram of exemplary components of an electronic device employing a display, in accordance with aspects of the present disclosure; 
         FIG. 2  is a perspective view of a computer in accordance with aspects of the present disclosure; 
         FIG. 3  is a front view of a user interface that may be employed to adjust the brightness of the display of  FIG. 1 , in accordance with aspects of the present disclosure; 
         FIG. 4  is a chart depicting a profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 5  is a chart depicting modified profiles for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 6  is a flowchart depicting a method for modifying a profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 7  is a front view of another embodiment of a user interface that may be employed to adjust the brightness of the display of  FIG. 1 , in accordance with aspects of the present disclosure; 
         FIG. 8  is a chart illustrating another embodiment of a profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 9  is a chart depicting a modified profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 10  is a chart depicting another modified profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 11  is a chart depicting minimum and maximum brightness levels, in accordance with aspects of the present disclosure; 
         FIG. 12  is a chart depicting a modified adjustment profile with clipped portions based on the minimum and maximum brightness levels, in accordance with aspects of the present disclosure; 
         FIG. 13  is a chart depicting another embodiment of a modified adjustment profile with clipped portions based on the minimum and maximum brightness levels, in accordance with aspects of the present disclosure; 
         FIG. 14  is a chart depicting a modified adjustment profile of a maximum slope, in accordance with aspects of the present disclosure; 
         FIG. 15  is a chart depicting a modified adjustment profile of a minimum slope, in accordance with aspects of the present disclosure; 
         FIG. 16  is a flowchart depicting another embodiment of a method for modifying a profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 17  is a chart illustrating a transition section of the profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 18  is a chart depicting another modified profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 19  is a chart depicting another modified profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 20  is a chart illustrating adjustment thresholds on the profile of  FIG. 17 , in accordance with aspects of the present disclosure; 
         FIG. 21  is a chart depicting modified profiles for adjusting display brightness based on adjustment thresholds, in accordance with aspects of the present disclosure; 
         FIG. 22  is a chart depicting further modified profiles for adjusting display brightness based on adjustment thresholds, in accordance with aspects of the present disclosure; 
         FIG. 23  is a chart depicting further modified profiles for adjusting display brightness based on adjustment thresholds, in accordance with aspects of the present disclosure; 
         FIG. 24  is a chart depicting further modified profiles for adjusting display brightness based on adjustment thresholds, in accordance with aspects of the present disclosure; 
         FIG. 25  is a flowchart depicting another embodiment of a method for modifying a profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 26  is a chart depicting a profile for adjusting display brightness along with a modified profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 27  is a chart depicting another modified profile for adjusting display brightness, in accordance with aspects of the present disclosure; 
         FIG. 28  is a chart depicting a profile for determining a brightness adjustment rate, in accordance with aspects of the present disclosure; 
         FIG. 29  is a chart depicting modified profiles for determining a brightness adjustment rate, in accordance with aspects of the present disclosure; 
         FIG. 30  is a flowchart depicting a method for adjusting display brightness using an adjustment rate, in accordance with aspects of the present disclosure; 
         FIG. 31  is a flowchart depicting a method for verifying that an ambient light change exceeds a threshold, in accordance with aspects of the present disclosure; 
         FIG. 32  is a schematic diagram of an environment where an electronic device may be used, in accordance with aspects of the present disclosure; 
         FIG. 33  is a chart depicting a response profile for an ambient light sensor, in accordance with aspects of the present disclosure; 
         FIG. 34  is a chart depicting an angular adjustment profile for determining a brightness adjustment based on an angle of ambient light, in accordance with aspects of the present disclosure; and 
         FIG. 35  is a flowchart depicting a method for adjusting display brightness based on an angle of ambient light, in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     The present disclosure is directed to techniques for controlling the brightness of displays based on ambient light conditions. Electronic devices may include displays that are illuminated by backlights. The electronic devices also may include one or more ambient light sensors that detect ambient light conditions, such as the ambient light level and/or the angle of an ambient light source. As ambient light conditions change, the electronic devices may adjust the brightness of the backlights based on one or more adjustment profiles stored within the electronic devices. 
     The adjustment profiles may define brightness levels that correspond to different ambient light levels. The slope and/or offset of the adjustment profiles may be modified in response to receiving a user input that adjusts display brightness. According to certain embodiments, an adjustment profile may include two or more sections that each correspond to different ambient light levels. For example, one section may correspond to low ambient light conditions while another section corresponds to high ambient light conditions. The sections may be modified independently of one another to allow different brightness responses to be used in different ambient light conditions. In certain embodiments, the slope and/or offset of a section may be adjusted in response to receiving a user input that changes the brightness setting for a certain ambient light level. 
     The electronic devices further may be designed to vary brightness levels based on the angle of incidence of one or more ambient light sources. For example, in certain embodiments, the electronic devices may include one or more ambient light sensors designed to perceive the ambient light level based on the angle of incidence of a light source. The perceived ambient light level may then be used to adjust the display brightness based on the one or more brightness adjustment profiles. In other embodiments, one or more ambient light sensors may be designed to detect the angle of incidence of an ambient light source. In these embodiments, the detected angle and the ambient light level may be used to adjust the display brightness. 
     The adjustment profiles also may define response rates for changing brightness levels based on ambient light conditions. The response rates may vary depending on the magnitude and/or direction of change in the ambient light conditions. In certain embodiments, the response rates may be designed to approximate the physical response of the human vision system. Further, in certain embodiments, noise reduction techniques may be employed by adjusting the response rates based on the magnitude of the change in the ambient light condition and/or based on whether the display is operating at steady state or executing a brightness adjustment. 
       FIG. 1  is a block diagram of an embodiment of an electronic device  10  that may make use of the brightness control techniques described above. Electronic device  10  may be any type of electronic device that includes a lighted display. For instance, electronic device  10  may be a media player, a mobile phone, a laptop computer, a desktop computer, a tablet computer, a personal data organizer, a workstation, or the like. According to certain embodiments, electronic device  10  may include a desktop or laptop computer, such as a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® Mini, or Mac Pro®, available from Apple Inc. of Cupertino, Calif. In other embodiments, electronic device  10  may be a handheld electronic device, such as a model of an iPad®, iPod® or iPhone® also available from Apple Inc., or electronic device  10  may be a display unit, such as an LED Cinema Display available from Apple Inc. In further embodiments, electronic device  10  may include other models and/or types of electronic devices employing lighted displays. 
     As shown in  FIG. 1 , electronic device  10  may include various internal and/or external components that contribute to the function of electronic device  10 . The various functional blocks shown in  FIG. 1  may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium), or a combination of both hardware and software elements. It should further be noted that  FIG. 1  is merely one example of a particular implementation and is intended to illustrate, but not limit, the types of components that may be present in electronic device  10 . 
     Electronic device  10  includes a display  12  that may be used to display image data, which may include stored image data (e.g., picture or video files stored in electronic device  10 ) and streamed image data (e.g., images received over a network), as well as live captured image data (e.g., photos or video taken using the electronic device  10 ). Display  12  also may display various images generated by electronic device  10 , including a graphical user interface (GUI) for an operating system or other application. Display  12  may be any suitable display such as a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or a cathode ray tube (CRT) display, for example. Additionally, in certain embodiments, display  12  may be provided in conjunction with a touch-sensitive element, such as a touchscreen, that may function as part of a control interface for device  10 . 
     Display  12  includes a backlight  14  that provides light to illuminate display  12 . According to certain embodiments, backlight  14  may be a fluorescent light panel or a light emitting diode (LED) array that emits light behind and/or beside an LCD display. In other embodiments, backlight  14  may include any suitable light source, such as a cathode ray tube, a cold cathode fluorescent lamp (CCFL), a metal halide arc lamp, lasers, or neon tubes, among others. 
     A display controller  16  may provide the infrastructure for receiving data from a processor  18  to show images on display  12 . For example, display controller  16  may include control logic for processing display commands from processor  18  to produce text and/or graphics on display  12 . Display controller  16  also may include one or more integrated circuits and associated components, such as resistors, potentiometers, voltage regulators, and/or drivers, and may be integrated with display  12  or may exist as a separate component. Further, in other embodiments, display controller  16  may be integrated with processor  18 . 
     Display controller  16  also may control backlight  14  to vary the brightness of display  12 . For example, display controller  16  may include control logic for varying the brightness of display  12  based on ambient light conditions. Display controller  16  also may include control logic for modifying adjustment profiles that specify how the brightness should be varied based on ambient light conditions. In certain embodiments, display controller  16  may adjust the voltage or current provided to backlight  14  to adjust the brightness of display  12 . For example, display controller  16  may vary a duty cycle of a pulse width modulation (PWM) signal for backlight  14 . 
     Display controller  16  also may adjust the brightness of display  12  based on feedback from one or more light sensors  20 . In certain embodiments, display controller  16  may be designed to update the brightness of display  12  at least at 60 times per second. Light sensors  20  may detect ambient light, such as sunlight, fluorescent light, and/or incandescent light, and may provide feedback to display controller  16  that indicates the level of ambient light. Further, light sensors  20  may be designed to detect and/or compensate for the angle of incidence of the ambient light. Light sensors  20  may include one or more optical sensors, such as photodiodes, phototransistors, photoresistors, or combinations thereof, among others, and may be integrated into display  12  or located in close proximity to display  12 . Further, in certain embodiments, light sensors  20  may be designed to perceive different colors and/or wavelengths in a manner consistent with that perceived by the human eye. In certain embodiments, light sensors  20  may be designed to detect ambient light levels at least at 20 times per second. According to certain embodiments, the detection rate of at least 20 times per second may be designed to enhance the responsiveness of display  12  to changes in ambient light levels. 
     Processor  18  may include one or more processors that provide the processing capability to execute the operating system, programs, user and application interfaces, and any other functions of electronic device  10 . Processor  18  may include one or more microprocessors and/or related chip sets. For example, processor  18  may include “general purpose” microprocessors, a combination of general and special purpose microprocessors, instruction set processors, graphics processors, video processors, related chips sets, and/or special purpose microprocessors. Processor  18  also may include on board memory for caching purposes. 
     Electronic device  10  also may include one or more I/O ports  22  designed to connect to a variety of external devices, such as a power source, headset or headphones, or other electronic devices such as computers, printers, projectors, external displays, modems, docking stations, and so forth. I/O ports  22  may support any interface type, such as a universal serial bus (USB) port, a video port, a serial connection port, an IEEE-1394 port, an Ethernet or modem port, an external S-ATA port, a proprietary connection port from Apple Inc., and/or an AC/DC power connection port, among others. 
     An I/O controller  24  may provide the infrastructure for exchanging data between processor  18  and input/output devices connected through I/O ports  22 . I/O controller  24  may contain one or more integrated circuits and may be integrated with processor  18  or may exist as a separate component. I/O controller  24  also may provide the infrastructure for receiving user input and/or feedback through one or more input devices  26  and a camera  27 . For instance, input devices  26  may be designed to control one or more functions of electronic device  10 , applications running on electronic device  10 , and/or any interfaces or devices connected to or used by electronic device  10 . Camera  27  may be used to capture images and video, and in certain embodiments, may be used to detect the angle of incidence of one or more ambient light sources. 
     User interaction with input devices  26 , such as to interact with a GUI or application interface displayed on display  12 , may generate electrical signals indicative of the user input. These input signals may be routed through I/O controller  24  via suitable pathways, such as an input hub or bus, to processor  22  for further processing. By way of example, input devices  26  may include buttons, sliders, switches, control pads, keys, knobs, scroll wheels, keyboards, mice, touchpads, and so forth, or some combination thereof. In one embodiment, input devices  26  may allow a user to navigate a GUI displayed on display  12  to control settings for adjusting the brightness of display  12 . 
     Information, such as programs and/or instructions, used by processor  18  may be located within storage  28 . Storage  28  may store a variety of information and may be used for various purposes. For example, storage  28  may store firmware for electronic device  10  (such as a basic input/output instruction or operating system instructions), various programs, applications, or routines executed on electronic device  10 , GUI functions, processor functions, and so forth. According to certain embodiments, storage  28  may store a program enabling control of brightness adjustments for display  12 . For example, storage  28  may store instructions and/or control logic that may be used by display controller  16  to modify adjustment profiles for changing the brightness of display  12 . Further, storage  28  may store one or more adjustment profiles  30  that may be employed by display controller  16  to vary the brightness of display  12 . In addition, storage  28  may be used for buffering or caching during operation of electronic device  10 . 
     Storage  28  may include any suitable manufacture that includes one or more tangible, computer-readable media. For example, storage  28  may include a volatile memory, such as random access memory (RAM), and/or as a non-volatile memory, such as read-only memory (ROM). The components may further include other forms of computer-readable media, such as non-volatile storage for persistent storage of data and/or instructions. The non-volatile storage may include flash memory, a hard drive, or any other optical, magnetic, and/or solid-state storage media. The non-volatile storage may be used to store firmware, data files, software, wireless connection information, and any other suitable data. 
     Electronic device  10  also may include a network device  32 , such as a network controller or a network interface card (NIC), for communicating with external devices. In one embodiment, network device  32  may be a wireless NIC providing wireless connectivity over any 802.11 standard or any other suitable wireless networking standard. Network device  32  may allow electronic device  10  to communicate over a network, such as a Local Area Network (LAN), Wide Area Network (WAN), or the Internet. Further, electronic device  10  may connect to and send or receive data with any device on the network, such as portable electronic devices, personal computers, printers, and so forth. Alternatively, in some embodiments, electronic device  10  may not include network device  32 . 
     Electronic device  10  may be powered by a power source  34  that may include one or more batteries and, or alternatively, an AC power source, such as provided by an electrical outlet. In certain embodiments, electronic device  10  may include an integrated power source that may include one or more batteries, such as a Li-Ion battery. In certain embodiments, a proprietary connection I/O port  22  may be used to connect electronic device  10  to a power source for recharging the battery. 
       FIG. 2  depicts an example of an electronic device  10 A in the form of a laptop computer. As shown in  FIG. 2 , electronic device  10 A includes a housing  36 A that supports and protects interior components, such as processors, circuitry, and controllers, among others. Housing  36 A also allows access to user input devices  26 A, such as a keypad, touchpad, and buttons, that may be used to interact with electronic device  10 A. For example, user input devices  26 A may be manipulated by a user to operate a GUI and/or applications running on electronic device  10 A. In certain embodiments, input devices  26 A may be manipulated by a user to adjust brightness settings and/or adjustment profiles  30  ( FIG. 1 ) for display  12 A. The brightness of display  12 A also may be adjusted based on feedback from one or more ambient light sensors  20 A. Electronic device  10 A also may include various I/O ports  22 A that allow connection of electronic device  10 A to external devices, such as a power source, printer, network, or other electronic device. 
       FIG. 3  depicts an embodiment of a GUI  38  that may be employed to adjust brightness settings for display  12 . GUI  38  may include various layers, windows, screens, templates, or other graphical elements that may be displayed in all, or a portion, of display  12 . For example, GUI  38  may include a window  40  that displays various options for adjusting the brightness of display  12 . Within window  40 , labels  42 ,  44 , and  46  identify graphical elements  48 ,  50 ,  52 ,  54 ,  56 , and  58  that may be adjusted by a user to change the brightness settings for display  12 . In particular, graphical element  48  may be a slider that a user may move along graphical element  50  to increase or decrease the light emitted by the lamp within backlight  14 . For example, a user may increase the lamp luminosity if she desires a brighter display  12  and may decrease the lamp luminosity if she desires a more dim display  12 . A user also may adjust the brightness settings by changing the perceived reflectivity of display  12 . The reflectivity adjustment may be varied to change how reflective the surface of display  12  appears to a user. For example, a user may move graphical element  52 , which may be a slider, along graphical element  54  to increase or decrease the perceived reflectivity of display  12 . Further, a user may adjust the rate of the brightness adjustment. For example, a user may move graphical element  56 , which may be may be a slider, along graphical element  58  to increase or decrease the rate of the brightness adjustment. A user may increase the response rate if she desires the brightness adjustment to be made quickly, while a user may decrease the response rate if she desires the brightness adjustment to be made more slowly. 
     A user may move graphical elements  48 ,  52 , and  56  using an input device  26  ( FIG. 1 ) of electronic device  10  ( FIG. 1 ). For example, a user may use a mouse, keyboard, or touchscreen to move graphical elements  48 ,  52 , and  56 . As described above with respect to  FIG. 1 , processor  18  may receive the user input through I/O controller  24  and may provide a control signal to display controller  16  to vary the brightness of backlight  14 . Based on the user input, display controller  16  also may modify one or more adjustment profiles  30  ( FIG. 1 ) that specify how the brightness should be adjusted. As may be appreciated, the graphical elements described herein are provided by way of example only, and are not intended to be limiting. In other embodiments, other types of graphical elements, such as virtual buttons, wheels, or the like, or other types of input devices, such as physical wheels, buttons, or the like, may be employed. 
       FIGS. 4 and 5  depict charts  64  and  65  of an adjustment profile  62  that may govern the changes in brightness for display  12  as the ambient light level changes. Charts  64  and  65  includes an x-axis  66  that represents ambient light levels and a y-axis  68  that represents brightness levels for display  12 . As indicated by adjustment profile  62 , the brightness of display  12  may generally increase as the ambient light level increases.  FIG. 4  shows how the offset of adjustment profile  62  may be modified in response to receiving a user adjustment for the lamp luminosity setting, while  FIG. 5  shows how the slope of adjustment profile  62  may be modified in response to receiving a user adjustment for the reflectivity setting. 
     As shown in  FIG. 4 , adjustment profile  62  intersects y-axis  68  at a point  70  that is offset from x-axis  66  by a distance  72 . When a user adjusts the lamp luminosity of display  12 , the offset for adjustment profile  62  may be increased or decreased in response to the user adjustment. For example, when a user moves graphical element  48  to the right along graphical element  50  ( FIG. 3 ), the offset may be increased to modify adjustment profile  62  to produce a modified adjustment profile  74 . Modified adjustment profile  74  intersects y-axis  68  at a point  76  that is offset from x-axis  66  by a distance  78 . As can be seen by comparing adjustment profiles  62  and  74 , distance  78  is greater than distance  72 , and accordingly, the offset of the adjustment profile has increased in response to increasing the lamp luminosity. In another example, when a user moves graphical element  48  to the left along graphical element  50  ( FIG. 3 ), the offset may be decreased to modify adjustment profile  62  to produce a modified adjustment profile  80 . Modified adjustment profile  80  intersects y-axis  68  at a point  82  that is offset from x-axis  66  by a distance  84 . As can be seen by comparing adjustment profiles  62  and  80 , distance  84  is less than distance  72 , and accordingly, the offset of the adjustment profile has decreased in response to decreasing the lamp luminosity. Further, as can be seen by comparing modified adjustment profiles  74  and  80  to adjustment profile  62 , the slope of the adjustment profiles has remained unchanged while the offset has increased or decreased in response to the user input. 
       FIG. 5  depicts how user adjustments to the reflectivity setting for display  12  may affect adjustment profile  62 . Similar to  FIG. 4 , adjustment profile  62  intersects y-axis at point  70 , which is offset from x-axis  66  by distance  72 . Adjustment profile  62  has a constant slope that defines a brightness response as the ambient light level changes. When a user adjusts the reflectivity setting of display  12 , the slope of adjustment profile  62  may be increased or decreased in response to the user adjustment. For example, when a user moves graphical element  52  to the right along graphical element  54  ( FIG. 3 ), the slope may be increased to modify adjustment profile  62  to produce a modified adjustment profile  86 . In another example, when a user moves graphical element  52  to the left along graphical element  54  ( FIG. 3 ), the slope may be decreased to modify adjustment profile  62  to produce a modified adjustment profile  88 . As can be seen by comparing modified adjustment profiles  86  and  88  to adjustment profile  62 , the offset (represented by distance  72 ) has remained unchanged while the slope has increased or decreased in response to the user input. 
     As shown in  FIG. 5 , the slope of adjustment profile  62  has been changed by rotating the adjustment profile about point  70  where adjustment profile  62  intersects y-axis  68 . In these embodiments, changes to the reflectivity setting have adjusted the slope without changing the offset of the adjustment profile. However, in other embodiments, the slope of adjustment profile  62  may be changed by rotating adjustment profile  62  around another point along adjustment profile  62 . In these embodiments, the changes to the slope also may result in a change to the offset of the adjustment profile. 
       FIG. 6  depicts a method  90  for modifying a brightness adjustment profile in response to user adjustment of the lamp luminosity and/or the display reflectivity setting. Method  90  may begin by receiving (block  92 ) a lamp adjustment. For example, as shown in  FIG. 3 , a user may adjust the lamp luminosity through GUI  38  of electronic device  10 . In response to receiving the lamp adjustment, display controller  16  may determine (block  94 ) the offset for the adjustment profile. For example, in certain embodiments, the position of slider  48  may determine the offset value; with the maximum offset value corresponding to the rightmost position along graphical element  50  and the minimum offset value corresponding to the leftmost position along graphical element  50 . However, in other embodiments, display controller  16  may determine an amount of change that should be applied to the current offset based on the amount and direction of movement in graphical element  48 . According to certain embodiments, display controller  16  may employ one or more algorithms and/or lookup tables, to calculate the new offset based on the user input. For example, display controller  16  may employ one or more algorithms and/or lookup tables to directly determine the new offset based on the user input. In another example, display controller  16  may then calculate the new offset by increasing or decreasing the current offset by the amount of change in the offset that corresponds to the user input. 
     Further, in certain embodiments, the offset may be dependent on both user input received through GUI  38  and the ambient light level. For example, electronic device  10  may measure the ambient light level through light sensor  20 , as described above with respect to  FIG. 1 . Based on the detected ambient light level, display controller  16  may determine the amount of change that should be applied to the offset in response to movement of graphical element  48  ( FIG. 3 ). In certain embodiments, display controller  16  may apply a smaller change to the offset when electronic device  10  is located in an environment with high ambient light levels than when electronic device  10  is located in an environment with lower ambient light levels. Further, in certain embodiments, the lamp of backlight  14  may be turned off when the ambient light level reaches a certain level. If the ambient light level is close to the ambient light level where the lamp may be turned off, display controller  16  may adjust the offset by only a small amount. On the other hand, if the ambient light level is low, display controller  16  may adjust the offset by a larger amount. 
     After determining (block  94 ) the offset, display controller  16  may modify (block  96 ) the current adjustment profile by increasing or decreasing the offset to the determined value. For example, display controller may use the determined offset in combination with the slope of the current adjustment profile to calculate a modified adjustment profile. In certain embodiments, display controller  16  may retrieve the current slope from storage  28  and may employ one or more algorithms to calculate the modified adjustment profile. According to certain embodiments, display controller  16  may produce modified adjustment profile  74  or  80 , as shown in  FIG. 4 . 
     Method  90  may continue by receiving (block  98 ) a reflectivity adjustment. For example, as shown in  FIG. 3 , a user may adjust the reflectivity setting through GUI  38  of electronic device  10 . In response to receiving the reflectivity adjustment, display controller  16  may determine (block  100 ) the slope for the adjustment profile. For example, in certain embodiments, the position of slider  52  may determine the slope value, with the maximum slope value corresponding to the rightmost position along graphical element  54  and the minimum slope value corresponding to the leftmost position along graphical element  54 . However, in other embodiments, display controller  16  may determine an amount of change that should be applied to the current slope based on the amount and direction of movement in graphical element  56 . According to certain embodiments, display controller  16  may employ one or more algorithms and/or lookup tables, to calculate the new slope based on the user input. For example, display controller  16  may employ one or more algorithms and/or lookup tables to directly determine the new slope based on the user input. In another example, display controller  16  may then calculate the new slope by increasing or decreasing the current offset by the amount of change in the slope that corresponds to the user input. 
     After determining the slope, display controller  16  may modify (block  102 ) the current adjustment profile by increasing or decreasing the slope to the determined value. For example, display controller may use the determined slope in combination with the offset of the current adjustment profile to calculate a modified adjustment profile. In certain embodiments, display controller  16  may retrieve the current offset from storage  28  and may employ one or more algorithms to calculate the modified adjustment profile. According to certain embodiments, display controller  16  may produce modified adjustment profile  86  or  88 , as shown in  FIG. 5 . 
     As shown in  FIG. 6 , method  90  includes modifying the adjustment profiles based on both lamp adjustments and reflectivity adjustments. However, in other embodiments, only a portion of method  90  may be performed. For example, if a user only adjusts the lamp luminosity, blocks  98  to  102 , which adjust the reflectivity, may be omitted. In another example, if a user only adjusts the reflectivity setting, blocks  92  to  96 , which adjust the lamp luminosity, may be omitted. 
       FIG. 7  depicts another embodiment of GUI  38  that may be employed to adjust a brightness setting for display  12 . In this embodiment, a single slider, or other suitable type of graphical element, may be manipulated by a user to vary both the lamp brightness and the perceived reflectivity. For example, window  104  includes a label  106  that identifies graphical elements  108  and  110  that may be adjusted by a user to change the brightness setting for display  12 . In particular, graphical element  108  may be a slider that a user may move along graphical element  110  to increase or decrease the brightness of display  12 . As graphical element  108  is moved along graphical element  110 , display controller  16  may vary both the slope and offset of the adjustment profile, as described below with respect to  FIGS. 8 to 15 . Window  104  also includes graphical element  56  that may be moved along graphical element  58  to adjust the response rate, as described above with respect to  FIG. 3 . 
     Window  104  includes a label  112  identifying graphical elements  114  and  116  that may be selected to enable profiles that determine the perceived reflectivity of display  12 . According to certain embodiments, the profiles may determine the amount of slope adjustment that is performed in response to movement of graphical element  108 . For example, the graphical element  114  may be selected to employ a slope adjustment designed to simulate the reflectivity of a book, while graphical element  116  may be selected to employ a slope adjustment designed to simulate the reflectivity of a newspaper. Further, in certain embodiments, graphical elements  114  and  116  may determine the type angular adjustment profile employed to compensate for ambient light angles, as described below with respect to  FIGS. 34 and 35 . 
     Window  104  further may include a label  118  identifying a graphical element, such as a selection box  120  that may be selected to disable a reflectivity adjustment for display  12 . When box  120  is selected, a reflectivity adjustment may not be performed when a user moves graphical element  108 . In particular, the slope of the adjustment profile or a section of the adjustment profile may remain constant, while only the offset is changed to increase or decrease the lamp brightness. However, when box  120  is not selected, both the slope and offset may be varied based on user input, as described below with respect to  FIGS. 8 to 15 . 
     Window also may include a label  122  identifying a graphical element, such as a selection box  124  that may be selected to disable an angular response for display  12 . When box  124  is not selected, the brightness of display  12  also may be adjusted based on the angle of incidence of the ambient light source, as described further below with respect to  FIGS. 34 and 35 . For example, the brightness of display  12  may be increased in direct light and decreased in indirect light to simulate the reflection of ambient light off of a hard copy material. When box  124  is selected, the angular response feature may be disabled and the brightness may be adjusted without accounting for the angle of incidence of the ambient light source. 
       FIG. 8  depicts an adjustment profile  130  shown on a chart  131  where x-axis  66  represents ambient light levels and y-axis  68  represents brightness levels for display  12 . Adjustment profile  130  may govern the changes in brightness for display  12  as the ambient light level changes. As indicated by adjustment profile  130 , the brightness of display  12  may generally increase as the ambient light level increases. 
     An ambient light threshold  132  may separate adjustment profile  130  into a bright section  134  shown generally to the right of ambient light threshold  132  and a dim section  136  shown generally to the left of ambient light threshold  132 . As shown, ambient light threshold  132  divides adjustment profile  130  into approximately equal sections. However, in other embodiments, ambient light threshold  132  may be disposed closer to or farther from y-axis  68  to provide other relative sizes of sections  134  and  136 . According to certain embodiments, ambient light threshold  132  may divide adjustment profile  130  so that dim section  136  represents approximately 5 to 20 percent of adjustment profile  130 . For example, in certain embodiments, dim section  136  may determine brightness levels ranging from 3 to 500 nits, or more specifically, 3 to 50 nits, while bright section  134  may determine brightness levels greater than approximately 150 nits. However, in other embodiments, ambient light threshold  132  may be disposed at any location along x-axis  66 . For example, in certain embodiments, ambient light threshold  132  may correspond to an ambient light level of approximately 15 to 200 lux, or more specifically, approximately 50 lux. 
     As shown, adjustment profile  130  has a constant slope that defines a brightness response as the ambient light level changes. Adjustment profile  130  intersects y-axis  68  at a point  135  that is offset from x-axis  66  by a distance  137 . As a user adjusts a brightness setting of display  12 , the slope and offset of adjustment profile  130  may be modified based on the adjusted brightness setting. To facilitate adjustment of the profile, adjustment profile  130  also may include transition points  138  and  140 . In particular, transition point  138  is located within bright section  134  of adjustment profile  130  and transition point  140  is located within dim section  136  of adjustment profile  130 . 
     When a user adjusts a brightness setting of display  12 , the slope of adjustment profile  130  may be modified such that the new brightness setting and the transition point  138  or  140  on the opposite side of ambient light threshold  132  both intersect the adjustment profile. For example, if a user makes a brightness adjustment through GUI  38  ( FIG. 7 ) while display  12  is located in an environment where the ambient light level exceeds ambient light threshold  132 , the slope may be adjusted until the new brightness setting and transition point  140  intersect the brightness adjustment profile, as described further below with respect to  FIG. 9 . Similarly, if a user makes a brightness adjustment through GUI  38  ( FIG. 7 ) while display  12  is located in an environment where the ambient light level is below ambient light threshold  132 , the slope may be adjusted until the new brightness setting and transition point  138  intersect the brightness adjustment profile, as described further below with respect to  FIG. 10 . 
     According to certain embodiments, transition points  138  and  140  may correspond to ambient light levels that may be set by a manufacturer to be a certain percentage or ambient light level above or below ambient light threshold  132 . For example, in certain embodiments, transition point  138  may correspond to an ambient light level of approximately 300 to 800 lux, or more specifically 300 to 600 lux. Transition point  140  may correspond to an ambient light level of approximately 0 to 50 lux, or more specifically, approximately 0 to 20 lux. However, in other embodiments, the ambient light levels corresponding to transition points  138  and  140  may vary depending on factors such as the ambient light levels where the electronic device is designed to be used, the operational range of the backlight, and/or the operational range of the ambient light sensor, among others. Further, the locations of transition points  138  and  140  on adjustment profile  130  may be adjusted by a user through a GUI. Moreover, in certain embodiments, the locations of transition points  138  and  140  may correspond to the most recent previous brightness setting input by a user for that section  134  or  136 . For example, transition point  138  may be the last brightness setting that was received when the ambient light level was above ambient light threshold  132 . Similarly, transition point  140  may be the last brightness setting that was received when the ambient light level was below ambient light threshold  132 . In this example, the locations of transitions points  138  and  140  may vary as a user adjusts the brightness of backlight  14 . However, in other embodiments, the locations of transition points  138  and  140  may remain fixed. 
       FIG. 9  depicts a modified adjustment profile  142  on a chart  143  along with the original adjustment profile  130 , shown in dashed lines. To produce modified adjustment profile  142 , a user has increased the brightness of display  12  from a current brightness setting  144  to a new brightness setting  146  at an ambient light level above ambient light threshold  132 . For example, as shown in  FIG. 7 , a user may move graphical element  108  to the right along graphical element  110  while display  12  is located in an environment that has an ambient light level that is greater than ambient light threshold  132 . 
     In response to receiving the new brightness setting, display controller  16  ( FIG. 1 ) may modify the slope of adjustment profile  130  to produce a modified adjustment profile  142  that intersects new brightness setting  146  and transition point  140 , which lies on the opposite side of ambient light threshold  132  from new brightness setting  146 . Modified adjustment profile  142  intersects y-axis  68  at a point  148  that is offset from x-axis  66  by a distance  150 . As seen by comparing the original adjustment profile  130  to the modified adjustment profile  142 , the adjustment profile has been increased in slope and decreased in offset. In other embodiments, where the new brightness setting is less than the current brightness setting  144 , the adjustment profile may be decreased in slope and increased in offset. 
       FIG. 10  is a chart  151  of another modified adjustment profile  152  that includes a modified slope. To produce modified adjustment profile  152 , a user has decreased the brightness of display  12  from a current brightness setting  154  to a new brightness setting  156  at an ambient light level below ambient light threshold  132 . For example, as shown in  FIG. 7 , a user may move graphical element  108  to the left along graphical element  110  while display  12  is located in an environment that has an ambient light level that is lower than ambient light threshold  132 . 
     In response to receiving the new brightness setting, display controller  16  ( FIG. 1 ) may modify the slope of adjustment profile  130  to produce a modified adjustment profile  152  that intersects new brightness setting  156  and transition point  138 , which lies on the opposite side of ambient light threshold  132  from new brightness setting  156 . Modified adjustment profile  152  intersects y-axis  68  at a point  158  that is offset from x-axis  66  by a distance  160 . As seen by comparing the original adjustment profile  130  to the modified adjustment profile  152 , the adjustment profile has been increased in slope and decreased in offset. In other embodiments, where the new brightness setting is greater than the current brightness setting  144 , the adjustment profile may be decreased in slope and increased in offset. 
       FIGS. 11 to 13  depict embodiments where portions of adjustment profile  130  may be clipped due to the operational range of backlight  14  ( FIG. 1 ). For example, backlight  14  may be capable of producing a brightness that ranges from a minimum brightness level  162  to a maximum brightness level  164 . As shown in  FIG. 11  on chart  165 , adjustment profile  130  may define a range of brightness levels within the minimum and maximum brightness levels  162  and  164 . If a user adjustment would produce a modified adjustment profile that would exceed the minimum brightness level  162  and/or the maximum brightness level  164 , a portion of the modified adjustment profile may be clipped to stay within the operational range of the backlight. 
     As shown in  FIG. 12  on chart  167 , a user may increase the brightness of display  12  from a current brightness setting  166  to a new brightness setting  168 . For example, a user may adjust the brightness setting through GUI  38  ( FIG. 7 ). In response to receiving a new brightness setting  168 , display controller  16  ( FIG. 1 ) may modify the slope of adjustment profile  130  to produce a modified adjustment profile  170  that intersects new brightness setting  168  and transition point  140 , which lies on the opposite side of ambient light threshold  132  from new brightness setting  168 . Modified adjustment profile  170  includes a sloped portion  172  that extends through new brightness setting  168  and transition point  140 . Modified adjustment profile  170  also includes clipped portions  174  and  176  that have a slope of approximately zero and that extend along minimum brightness level  162  and maximum brightness level  164 , respectively. Accordingly, clipped portions  174  and  176  prevent modified adjustment profile  170  from extending beyond the operation range of backlight  14 . 
     As shown in  FIG. 12 , modified adjustment profile  172  includes two clipped portions  174  and  176 . However, in other embodiments, modified adjustment profile  172  may include only one clipped portion  174  or  176 , depending upon the operational range of backlight  14 . Further, in certain embodiments, rather than having a slope of zero, the clipped portions may have a slope that transitions the clipped portions to just inside of or equal to the maximum and minimum brightness levels. For example, as shown in  FIG. 13  on chart  169 , modified adjustment profile  170  may include transition points  178  and  180  that allow the clipped portions to transition to the minimum and maximum brightness levels  162  and  164 . In particular, modified adjustment profile  170  may include a clipped portion  182  that extends between transition point  178  and minimum brightness level  162  and a clipped portion  184  that extends between transition point  180  and maximum brightness level  164 . According to certain embodiments, transition points  178  and  180  may be set by a manufacturer to occur at certain ambient light levels or at a percentage of the maximum and minimum brightness levels. 
       FIGS. 14 and 15  depict charts  185  and  187  of embodiments where the locations of transition points  138  and  140  may be modified to ensure that the slope of the adjustment profile is not less than a minimum slope or greater than a maximum slope. According to certain embodiments, a minimum slope, which is just slightly greater than zero, may be employed so that the display does not appear unresponsive to user adjustments. In certain embodiments, the minimum slope may be a set value. However, in other embodiments, the minimum slope may vary as the ambient light level changes and/or as the display brightness changes. For example, at low ambient light levels, a smaller minimum slope may be employed than at high ambient light levels. In certain embodiments, the minimum slope may be based on a percentage of the ambient light level and/or of the display brightness. For example, in certain embodiments, the minimum slope may be calculated by maintaining a minimum difference, such as 50 percent, between the brightness settings for transition points  138  and  140 . According to certain embodiments, transition point  140  may be adjusted to have a brightness that is at least 30 to 80 percent as bright as the brightness of transition point  138 . Further, in certain embodiments, the minimum difference between the brightness settings (y-axis values) for transition points  138  and  140  may vary based on the difference between the ambient light levels (x-axis values) for transition points  138  and  140 . In certain embodiments, the minimum slope may be a set value. For example, in certain embodiments where x-axis  66  represents ambient light levels in lux and y-axis  68  represents brightness levels in nits, the minimum slope may be approximately 0.1. In other embodiments, the minimum slope may be set to zero. 
     According to certain embodiments, a maximum slope may be employed to limit the amplification of noise as brightness adjustments are performed. In certain embodiments, the maximum slope may be a set value. For example, in embodiments where x-axis  66  represents ambient light levels in lux and y-axis  68  represents brightness levels in nits, the maximum slope may have a value of approximately 0.66 to 2, or more specifically, the maximum slope may be 1. However, in other embodiments, the value of the maximum slope may vary depending on factors such as the maximum brightness of display  14  or the environment where electronic device  10  is designed to be used, among others. 
       FIG. 14  depicts an embodiment where display controller  16  may set the modified adjustment profile to a maximum slope rather than to a slope that is determined by intersecting a new brightness setting with a transition point  138  or  140 . For example, a user may enter a new brightness setting  186  through GUI  38  ( FIG. 7 ). In response to receiving new brightness setting  186 , display controller  16  ( FIG. 1 ) may modify the slope of adjustment profile  130  to produce a modified adjustment profile  188 . However, rather than setting modified adjustment profile  130  to interest new brightness setting  186  and transition point  140 , which is on the opposite side of ambient light threshold  132  from new brightness setting  186 , display controller  16  may determine a modified transition point  190  that produces the maximum slope when intersected with new brightness setting  186 . Modified transition point  190  may correspond to the same ambient light level on x-axis  66  as transition point  140 . However, modified transition point  190  may correspond to a new brightness level on y-axis  68 . In particular, modified transition point  190  may be offset from the existing transition point by a distance  192  just large enough to keep modified transition point  190  from exceeding the maximum slope. Accordingly, by adjusting the brightness level of transition point  140 , the modified adjustment profile has the maximum allowed slope. Modified adjustment profile  188  then intersects new brightness setting  186  and modified transition point  190 . In other embodiments, the ambient light level for transition point  140  may be adjusted to produce the maximum slope. For example, transition point  140  may be moved to the left along x-axis  66  to produce a modified adjustment profile with the maximum slope. 
       FIG. 15  depicts an embodiment where the modified adjustment profile may be set to the minimum slope. For example, a user may enter a new brightness setting  194  through GUI  38  ( FIG. 7 ). In response to receiving new brightness setting  194 , display controller  16  ( FIG. 1 ) may modify the slope of adjustment profile  130  to produce a modified adjustment profile  196 . However, rather than setting modified adjustment profile  130  to interest new brightness setting  194  and transition point  140 , which is on the opposite side of ambient light threshold  132  from new brightness setting  186 , display controller  16  may determine a modified transition point  198  that produces the minimum slope when intersected with new brightness setting  194 . Modified transition point  198  may correspond to the same ambient light level on x-axis  66  as transition point  140 . However, modified transition point  198  may correspond to a new brightness level on y-axis  68 . In particular, modified transition point  198  may be offset from the existing transition point by a distance  200  just large enough to keep modified transition point  190  from having a slope smaller than the minimum. 
       FIG. 16  depicts a method  202  for modifying a brightness adjustment profile. Method  202  may begin by receiving (block  204 ) a brightness setting. For example, as shown in  FIG. 7 , a user may adjust the brightness through a GUI  38  of electronic device  10 . In response to receiving a brightness setting, electronic device  10  may detect (block  206 ) the current ambient light level. For example, electronic device  10  may measure the ambient light level through light sensor  20 , as described above with respect to  FIG. 1 . 
     Based on the detected ambient light level, display controller  16  may determine (block  208 ) the transition point to use for the modified adjustment profile. For example, as shown in  FIG. 8 , display controller  16  may compare the detected ambient light level to the ambient light threshold  132  and select the transition point on the opposite side of the ambient light threshold from the detected ambient light level. If the detected ambient light level is greater than ambient light threshold  132 , display controller  16  may select transition point  140 . On the other hand, if the detected ambient light level is below ambient light threshold  132 , display controller  16  may select transition point  138 . According to certain embodiments, display controller  16  may retrieve the transition point from storage  28 . 
     Display controller  16  may then determine (block  210 ) whether the slope of a modified adjustment profile that would intersect the new brightness setting and the transition point would be within the maximum and minimum slope range. For example, display controller  16  may calculate the slope of a line that insects the new brightness setting and the selected transition point. In certain embodiments, display controller  16  may calculate the slope using one or more algorithms or lookup tables. Display controller  16  may then determine whether the adjusted slope would be less than or equal to the maximum slope and greater than or equal to the minimum slope. If the slope is within range, display controller  16  may modify (block  212 ) the adjustment profile to interest with the determined transition point and the new brightness setting. For example, display controller  16  may generate a modified adjustment profile based on the adjusted slope that was used to determine (block  210 ) whether the adjusted would be in range. According to certain embodiments, display controller  16  may produce modified adjustment profile  142  or  152  as shown in  FIGS. 9 and 10 . 
     On the other hand, if the slope is not within the maximum and minimum slope range, display controller  16  may modify (block  214 ) the determined transition point. Display controller  16  may adjust the brightness level (y-axis) of the transition point by an amount needed to produce the maximum or minimum slope. For example, display controller  16  may retrieve the existing x-axis coordinate for the transition point, for example, from storage  28 . Display controller  16  may then use one or more algorithms or lookup tables to calculate the y-axis coordinate that would produce the maximum or minimum slope. Display controller  16  may then store the existing x-axis coordinate and the new y-axis coordinate as the new transition point. According to certain embodiments, display controller  16  may produce a modified transition point  190  or  198  as shown in  FIGS. 14 and 15 . Further, in certain embodiments, display controller  16  may adjust the ambient light level (x-axis) of the transition point instead of, or in addition to, adjusting the brightness level. Display controller  16  may then modify (block  212 ) the adjustment profile to interest the modified transition point and the new brightness setting. 
     After modifying (block  212 ) the adjustment profile, display controller  16  may determine whether the modified adjustment profile exceeds the operational range of backlight  14 . For example, display controller  16  may determine whether the modified adjustment profile specifies a brightness that is greater than the maximum brightness or less than the minimum brightness that may be produced by backlight  14 . If the modified adjustment profile is within the operational range, the modified adjustment profile may be stored (block  218 ). For example, display controller  16  may store the modified adjustment profile in storage  28  ( FIG. 1 ) of electronic device  10 . 
     On the other hand, if display controller  16  determines (block  216 ) that the modified adjustment profile exceeds the operational range, display controller  16  may clip (block  220 ) portions of the adjustment profile that fall outside of the operational range. For example, as shown in  FIG. 12 , display controller  16  may set portions of the modified adjustment profile that would exceed the operational range to the maximum and minimum brightness levels. In another example, as shown in  FIG. 13 , display controller  16  may transition portions of the adjustment profile to the maximum and minimum brightness levels. Display controller  16  may then store (block  218 ) the modified profile. 
       FIGS. 17 through 19  illustrate another method of modifying an adjustment profile in response to receiving a new brightness setting. Rather that modifying the slope of the entire adjustment profile, each section  134  and  136  may be modified independently of the other section  136  or  134  to provide different brightness responses for each section  134  and  136 . In particular, the slope of each section  134  and  136  may be changed independently of the slope of the other section  136  or  134 . 
     According to certain embodiments, the slope of a section  134  or  136  may be modified when a user adjusts a brightness setting while display  12  is located in an environment with an ambient light level within that section  134  or  136 . For example, if a user makes a brightness adjustment through GUI  38  ( FIG. 7 ) while display  12  is located in an environment where the ambient light level exceeds ambient light threshold  132 , the slope of bright section  134  may be adjusted. Similarly, if a user makes a brightness adjustment through GUI  38  ( FIG. 7 ) while display  12  is located in an environment where the ambient light level is below ambient light threshold  132 , the slope of dim section  136  may be adjusted. In other embodiments, the slope of sections  134  and  136  may be modified based on user inputs received through GUI  38  that specify the section  134  or  136  to modify. For example, a GUI may include one or more graphical elements corresponding to each section  134  and  136  that may be manipulated to adjust the slope of each section  134  or  136  individually. 
     As shown on chart  219  of  FIG. 17 , in addition to transition points  138  and  140 , adjustment profile  130  may include a transition section  220 , generally defined as the section of the adjustment profile between transition points  138  and  140 . Transition section  220  may include a portion of bright section  134  and a portion of dim section  136  and may be modified along with either bright section  134  or dim section  136  to provide a smoother transition between sections  134  and  136  of adjustment profile  130 . For example, when a slope of bright section  134  is adjusted, the slope of transition section  220  also may be adjusted to provide a more gradual change from bright section  134  to dim section  136 . Similarly, when the slope of dim section  136  is adjusted, the slope of transition section  220  also may be adjusted to provide a smoother transition from dim section  136  to bright section  130 . 
       FIG. 18  depicts a modified adjustment profile  222  on a chart  223  along with the original adjustment profile  130 , shown in dashed lines. To produce modified adjustment profile  222 , a user has increased the brightness of display  12  from a current brightness setting  224  to a new brightness setting  226  at an ambient light above ambient light threshold  132 . For example, as shown in  FIG. 7 , a user may move graphical element  108  to the right along graphical element  110  while display  12  is located in an environment that has an ambient light level that is greater than ambient light threshold  132 . 
     In response to receiving the new brightness setting, display controller  16  ( FIG. 1 ) may modify the bright section  134  of adjustment profile  130  until bright section  134  intersects with the new brightness setting  226 . In particular, display controller  16  may select the transition point  140  that lies on the opposite side of ambient light threshold  132  from new brightness setting  226 . Display controller  16  may then increase the slope of each section  220  and  134  that lies to the right of transition point  140 . As seen by comparing the original adjustment profile  130  to the modified adjustment profile  222 , the transition section  220  and bright section  134  have been increased in slope so that both transition point  140  and new brightness setting  226  intersect modified adjustment profile  222 . In other embodiments where the new brightness setting is less than the current brightness setting  224 , transition section  220  and bright section  134  may be decreased in slope until the new brightness setting and transition point  140  both intersect the modified adjustment profile. 
       FIG. 19  is a chart  227  of a modified adjustment profile  228  that includes a modified dim section  136  and transition section  220 . To produce modified adjustment profile  228 , a user has decreased the brightness of display  12  from a current brightness setting  230  to a new brightness setting  232  at an ambient light level below ambient light threshold  132 . For example, as shown in  FIG. 7 , a user may move graphical element  108  to the left along graphical element  110  while display  12  is located in an environment that has an ambient light level that is lower than ambient light threshold  132 . 
     In response to receiving the new brightness setting, display controller  16  ( FIG. 1 ) may modify the dim section  136  of adjustment profile  130  until dim section  136  intersects the new brightness setting  232 . In particular, display controller  16  may select the transition point  138  that lies on the opposite side of ambient light threshold  132  from new brightness setting  232 . Display controller  16  may then increase the slope of each section  220  and  136  that lies to the left of transition point  138 . As seen by comparing the original adjustment profile  130  to the modified adjustment profile  228 , the transition section  220  and dim section  136  have been increased in slope so that both transition point  138  and new brightness setting  232  intersect modified adjustment profile  228 . In other embodiments, where the new brightness setting is greater than the current brightness setting  230 , transition section  220  and dim section  136  may be decreased in slope until the new brightness setting and transition point  138  both intersect the modified profile. 
     As shown in  FIGS. 8 through 19 , the slope of sections  134 ,  136 , and/or  220  may be adjusted in response to receiving new brightness settings. Further, in other embodiments where sections  134 ,  136 , and  220  may have curved portions, the steepness of curved portions may be increased and/or decreased providing a relative slope change for the curved portions. 
     In certain embodiments, rather than adjusting the slope to intersect with a new brightness setting, the slope may be adjusted to intersect with a maximum or minimum brightness level. For example, as shown in  FIGS. 12 and 13 , a portion of the adjustment profile may be clipped to intersect with the maximum or minimum brightness level as defined by the operational range of the backlight. Further, as shown in  FIGS. 20 to 22  on charts  233 ,  235 , and  237 , transition points  138  and  140  may define a maximum brightness threshold  234  and a minimum brightness threshold  236 , respectively, that may limit the amount of slope adjustments made to sections  134 ,  136 , and  220 . In particular, transition point  138  may define a maximum brightness threshold  234  that may be used when making adjustments to dim section  136 , and transition point  140  may define a minimum brightness threshold  236  that may be used when making adjustments to bright section  134 . According to certain embodiments, when a brightness setting is input by a user that is above or below one of the brightness thresholds  234  or  236 , respectively, the corresponding section  136  or  134  may be adjusted to a minimum slope at the brightness threshold  234  or  236 , rather than to the brightness setting input by the user. However, in other embodiments, the corresponding section  136  or  134  may be adjusted to the minimum slope at the point where the new brightness setting intersects the corresponding section  136  or  134 . 
       FIG. 21  depicts a modified adjustment profile  238  where bright section  134  has been adjusted to minimum brightness threshold  236 . In particular, a user has entered a new brightness setting  240  that would decrease the brightness from the current brightness  224  to the new brightness setting  240 , which is below brightness threshold  236 . Rather than adjusting bright section  134  to a level below brightness threshold  236 , display controller  16  has created modified adjustment profile  238  where bright section  134  has a slope of zero and corresponds to brightness threshold  236 . The use of minimum brightness threshold  236  may generally ensure that the display  12  does not decrease in brightness when a user moves display  12  from a dim area to a bright area. 
     In another embodiment, a new brightness setting that is below minimum brightness threshold  236  may produce a modified adjustment profile  242 , shown by the dotted and dashed line. Modified adjustment profile  242  includes a portion  244  that has a slope of zero and intersects new brightness setting  240  and an intersection point  246  with dim section  136 . Modified adjustment profile  242  also includes the portion  248  of dim section  136  that has a brightness level below the new brightness setting  240 . According to certain embodiments, a user may be able to select which modified adjustment profile  238  or  242  should be used when minimum threshold  236  is exceeded. For example, a user may choose the type of minimum threshold adjustment that is made through a GUI of electronic device  10 . However, in other embodiments, the type of minimum threshold adjustment that is employed may be set by a manufacturer or third party. 
       FIG. 22  illustrates a modified profile  250  where dim section  136  has been adjusted to maximum brightness threshold  234 . In particular, a user has entered a new brightness setting  252  that would increase the brightness from the current brightness setting  230  to the new brightness setting  252 , which is above brightness threshold  234 . Rather than adjusting dim section  136  to a level above brightness threshold  234 , display controller  16  has created modified profile  250  where dim section  136  has a slope of zero and corresponds to brightness threshold  234 . The use of maximum brightness threshold  234  may generally ensure that display  12  does not increase in brightness when a user moves display  12  from a bright area to a dim area. 
     In another embodiment, a new brightness setting that is above maximum brightness threshold  234  may produce a modified adjustment profile  254 , shown by the dotted and dashed line. Modified adjustment profile  254  includes a portion  256  that has a slope of zero and intersects new brightness setting  252  and an intersection point  258  with bright section  134 . Modified adjustment profile  254  also includes the portion  260  of dim section  136  that has a brightness level above the new brightness setting  252 . As noted above with respect to  FIG. 21 , a user may be able to select which modified profile  250  or  254  should be used when maximum threshold  234  is exceeded, or the type of adjustment that is made may be set by a manufacturer or third party. 
     Further, in certain embodiments, rather than setting portions of the slope of an adjustment profile to zero when a threshold  234  or  236  is exceeded, a minimum slope greater than zero may be employed. According to certain embodiments, employing a minimum slope greater than zero may ensure that display  12  appears responsive to user brightness adjustments. As discussed above with respect to  FIGS. 14 and 15 , in certain embodiments, the minimum slope may be a set value. However, in other embodiments, the minimum slope may vary as the ambient light level changes and/or as the display brightness changes. 
       FIG. 23  is a chart  261  of a modified adjustment profile  262  where bright section  134  has been adjusted to have a minimum slope in response to a user entering new brightness setting  240 , which is below minimum brightness threshold  236 . Rather than adjusting bright section  134  to a level below brightness threshold  236 , display controller  16  has created modified adjustment profile  262  where bright section  134  extends from transition point  140  at the minimum slope. In another embodiment, a new brightness setting that is below minimum brightness threshold  236  may produce a modified adjustment profile  264 , shown by the dotted and dashed line. Modified adjustment profile  264  includes a portion  266  that has a slope that corresponds to the minimum slope and intersects new brightness setting  240  and an intersection point  268  with dim section  136 . Modified adjustment profile  264  also includes the portion  270  of dim section  136  that has a brightness level below intersection point  268 . 
       FIG. 24  is a chart  271  of a modified adjustment profile  272  where dim section  136  has been adjusted to have a minimum slope in response to a user entering new brightness setting  252 , which is above maximum brightness threshold  234 . Rather than adjusting dim section  136  to a level above brightness threshold  234 , display controller  16  has created modified adjustment profile  272  where bright section  134  extends from transition point  138  at the minimum slope. In another embodiment, a new brightness setting that is above maximum brightness threshold  234  may produce a modified adjustment profile  274 , shown by the dotted and dashed line. Modified adjustment profile  274  includes a portion  276  that has a slope that corresponds to the minimum slope and intersects new brightness setting  252  and an intersection point  278  with bright section  134 . Modified adjustment profile  274  also includes the portion  280  of bright section  134  that has a brightness level above intersection point  278 . 
       FIG. 25  depicts a method  282  for modifying a brightness adjustment profile where the bright and dim sections may be modified independently of one another. Method  282  may begin by receiving (block  284 ) a brightness setting. For example, as shown in  FIG. 7 , a user may adjust the brightness through a GUI  38  of electronic device  10 . In response to receiving a brightness setting, electronic device  10  may detect (block  286 ) the current ambient light level. For example, electronic device  10  may measure the ambient light level through light sensor  20 , as described above with respect to  FIG. 1 . 
     Based on the detected ambient light level, display controller  16  may determine (block  288 ) the section of the adjustment profile that corresponds to the detected ambient light level. For example, as shown in  FIG. 17 , display controller  16  may compare the detected ambient light level to the ambient light threshold  132 . If the detected ambient light level is greater than ambient light threshold  132 , display controller  16  may select bright section  134 . On the other hand, if the detected ambient light level is below ambient light threshold  132 , display controller  16  may select dim section  136 . According to certain embodiments, display controller may use one or more algorithms and/or lookup tables to determine the section of the adjustment profile that corresponds to the detected ambient light level. Further, in certain embodiments, display controller  132  may retrieve ambient light threshold  132  from storage  28 . 
     Display controller  16  may then determine (block  290 ) whether the received brightness setting exceeds a brightness threshold for the selected adjustment profile section. For example, if the selected section is bright section  134 , display controller  16  may determine whether the brightness setting is less than brightness threshold  236  ( FIG. 20 ). In another example, if the selected section is dim section  136 , display controller  16  may determine whether the received brightness setting is greater than brightness threshold  234  ( FIG. 20 ). According to certain embodiments, brightness thresholds  234  and  236  may be stored in storage  28 . 
     If the brightness setting does not exceed the threshold, display controller  16  may then modify (block  292 ) the selected section to intersect with the new brightness setting and the corresponding transition point. For example, if the selected section if bright section  134 , display controller  16  may use transition point  140  as the corresponding transition point, as shown in  FIG. 18 . In another example, if the selected section if dim section  136 , display controller  16  may use transition point  138  as the corresponding transition point, as shown in  FIG. 19 . Display controller  16  may then adjust the slope of the selected section until the received brightness setting and the corresponding transition point intersect with the modified adjustment profile, for example, as shown in  FIGS. 18 and 19 . According to certain embodiments, display controller  16  may use one or more algorithms to adjust and/or calculate the new slope. The modified adjustment profile may then be stored (block  294 ). For example, display controller  16  may store the modified adjustment profile in storage  28  ( FIG. 1 ) of electronic device  10 . 
     On the other hand, if display controller  16  determines (block  290 ) that the received brightness setting exceeds the threshold, display controller  16  may modify (block  296 ) the selected section to have a minimum slope. For example, as shown in  FIG. 21 , if the received brightness setting  240  is below brightness threshold  236 , display controller  16  may adjust bright section  134  to the brightness threshold  236 , as illustrated by modified adjustment profile  238 . In another embodiment shown in  FIG. 21 , if the received brightness setting  240  is below brightness threshold  236 , display controller  16  may adjust a portion  244  of the profile to have a zero slope that intersects the received brightness setting  240 , as illustrated by modified adjustment profile  242 .  FIG. 22  depicts similar examples where the received brightness setting  252  is above brightness threshold  236 . For example, as shown in  FIG. 22 , if the received brightness setting  252  is above brightness threshold  234 , display controller  16  may adjust dim section  136  to the brightness threshold  234 , as illustrated by modified adjustment profile  250 . In another embodiment shown in  FIG. 22 , if the received brightness setting  240  is above brightness threshold  234 , display controller  16  may adjust a portion  256  of the profile to have a zero slope that intersects the received brightness setting  252 , as illustrated by modified adjustment profile  254 . 
     Further, in certain embodiments, the minimum slope may be greater than zero. For example, as shown in  FIGS. 23 and 24 , a minimum slope may be employed when a new brightness setting  224  is above brightness threshold  236  or below brightness threshold  234 . In particular, display controller  16  may adjust a portion of the adjustment profile to have a minimum slope greater than zero. For example, as shown in  FIG. 23 , display controller  16  may adjust bright section  134  to have a minimum slope that intersects transition point  140 , as illustrated by modified adjustment profile  262 . In another embodiment shown in  FIG. 23 , display controller  16  may adjust a portion  266  of the profile to have a minimum slope that intersects with received brightness setting  240 . As shown in  FIG. 24 , display controller  16  may adjust dim section  136  to have a minimum slope that intersects transition point  138 , as illustrated by modified adjustment profile  272 . In another embodiment shown in  FIG. 24 , display controller  16  may adjust a portion  276  of the profile to have a minimum slope that intersects with received brightness setting  252 . Display controller  16  may then store (block  294 ) the modified profile. 
       FIG. 26  depicts another embodiment of a chart  298  with a brightness adjustment profile  300  that may be used to change the brightness of display  12  as the ambient light level changes. Chart  298  includes two ambient light thresholds  302  and  304  that divide adjustment profile  300  (shown in the dashed lines) into three different sections  306 ,  308 , and  310 . In particular, bright section  306  includes ambient light levels above threshold  302 ; dim section  310  includes ambient light levels below threshold  304 ; and intermediate section  308  includes ambient light levels between ambient light thresholds  302  and  304 . Each section  306 ,  308 , and  310  also includes a transition point  312 ,  314 , and  316  that may be employed to provide smooth transitions between each section  306 ,  308 , and  310 . 
     A user may adjust the brightness setting for display  12  when display  12  is located in environments having different ambient light levels. For example, in the illustrated embodiment, a modified profile  318  has been produced where two user adjustments were made in different ambient light levels. In particular, a user has entered a brightness setting  320  while display  12  was located in an environment with an ambient light level above ambient light threshold  302  and a user has entered a brightness setting  322  while display  12  was located in an environment with an ambient light level below ambient light threshold  304 . In response to receiving brightness setting  320 , the slope of bright section  306  has been increased so that bright section  306  now intersects transition point  314  and new brightness setting  320 . In response to receiving brightness setting  322 , the slope of dim section  310  has been increased so that dim section  310  now intersects transition point  314  and new brightness setting  322 . Accordingly, transition point  314  may be employed as the transition point corresponding to both bright section  306  and dim section  310 . 
       FIG. 27  depicts slope adjustments that may be made within intermediate section  308 . In particular, a user has entered a new brightness setting  324  while display  12  was located in an area with an ambient light level greater than threshold  304  but less than threshold  302 . In response to receiving the new brightness setting, intermediate section  308  has been changed in slope to produce a modified adjustment profile  326 . In particular, the portion of intermediate section  308  to the right of new brightness setting  172  intersects with new brightness setting  172  and transition point  312  while the portion of intermediate section  308  to the left of new brightness setting  172  intersects with new brightness setting  172  and transition point  316 . Accordingly, two transition points  312  and  316  may be employed as the transition points corresponding to intermediate section  308 . 
     In other embodiments, any number of brightness settings may be entered by a user and employed by display controller  16  to modify the slope of one or more sections  306 ,  308 , and  310  of an adjustment profile  300 . Further, in other embodiments, any number of thresholds  302  and  304  may be employed to produce any number of sections that may be independently adjusted within a modified profile. Further, as noted above, rather than straight lines, each section may include one or more curved portions. 
       FIGS. 4 to 27  describe brightness adjustment profiles that may be employed by display controller  16  to modify the display brightness as the ambient light level changes. As discussed below with respect to  FIGS. 28 and 29 , display controller  16  also may determine the rate at which the brightness is adjusted using one or more adjustment rate profiles. According to certain embodiments, an adjustment rate profile may be designed to approximate the physiological adjustment of the human eye. For example, the human eye may adapt to dimmer conditions more slowly than the human eye adapts to bright conditions. Accordingly, the adjustment rate profile may be designed to dim the display relatively slowly and brighten the display relatively quickly. Further, in certain embodiments, the adjustment rate profile may be designed to adjust the display at a rate that is substantially equal to the physiological adjustment rate of the human eye. According to certain embodiments, the adjustment rate profile may be designed to take approximately 10 seconds to reduce the brightness by a factor of 10, approximately 5 seconds to reduce the brightness by a factor of 3, and approximately 5 seconds to reduce the brightness by a factor of 1.5. Further, according to certain embodiments, the adjustment rate profile may be designed to take approximately 5 seconds to increase the brightness by a factor of 1.5 and approximately 1 to 2 seconds to increase the brightness by a factor of 2 or more. However, in other embodiments, the specific length of time for reducing the brightness may vary based on factors such as the type and/or size of the display. 
       FIG. 28  is a chart  326  depicting an embodiment of an adjustment rate profile  328 . Chart  326  includes an x-axis  330  that shows the magnitude of change in the display brightness (or, in other embodiments, the magnitude of change in the ambient light level) and a y-axis  332  that shows the adjustment rate for changing the brightness of display  12 . The current display brightness setting may be represented as a line  334  that indicates zero deviation from the current display brightness setting. According to certain embodiments, the magnitude of change shown on x-axis  330  may represent the ratio or percentage of change in the current display brightness, and the rate of change shown on y-axis  332  may represent the ratio of change in the current display brightness divided by the time constant (i.e., the time it takes to complete the change). In certain embodiments, the time constant may vary based on the magnitude of change. For example, in certain embodiments, the time constant may decrease as the magnitude of change increases. 
     As shown, adjustment rate profile  328  is asymmetrical. In particular, adjustment rate profile  328  includes a relatively shallow curved section  336  for dimming the display at a relatively slow rate and includes a steeper section  338  for brightening the display at a faster rate. Consequently, it may take longer to reduce the brightness than it takes to increase the brightness. As noted above, the time it takes to complete a brightness change may be represented by a time constant. In certain embodiments, the following time constants (i.e. the time it takes to complete the brightness change) may be employed: a time constant of approximately 8 seconds may be used to reduce the brightness by one-fifth; a time constant of approximately 12 seconds may be used to reduce the brightness by two-thirds, one-half, and one-fourth; a time constant of approximately 10 seconds may be used to increase the brightness by one-third; a time constant of approximately 6 seconds may be used to increase the brightness by one-half; a time constant of approximately 2 seconds may be used double the brightness; and a time constant of approximately 1.4 seconds may be used to triple the brightness. According to certain embodiments, shallow curved section  336  may be designed to approximate the physiological response of the human eye, which adjusts relatively slowly to decreased lighting. Similarly, steeper section  338  may be designed to approximate the physiological response of the human eye, which adjusts relatively quickly to increased lighting. According to certain embodiments, an asymmetry of about one order of magnitude may exist between the rate of change for shallow curved section  336  and the rate of change for steeper section  338 . Further, in certain embodiments, the adjustment rate profile  328  may be designed to provide a rate of change that ranges from approximately equal to or twice as fast as the physiological response of the human eye. However, in other embodiments, the particular curvatures and/or the relative steepness of sections  338  and  340  may vary. 
     Adjustment rate profile  328  also includes a relatively flat section  340  that provides a fairly slow rate of change for small changes in brightness. When the magnitude of change in brightness is relatively small, for example, less than approximately one-third of the current brightness setting, a relatively slow rate of change may be used to adjust the display, regardless of the direction of change. Further, the same rate of change may be employed for small magnitudes of change in the brightness. In other embodiments, the same time constant may be employed for small magnitudes of change in the brightness. In other words, it may take approximately the same amount of time to complete a brightness change that is smaller than a certain amount. For example, in certain embodiments, it may take the same amount of time to adjust the display to a new brightness that is between approximately one third less than the current brightness and one third greater than the current brightness. According to certain embodiments, a time constant of approximately 6 to 12 seconds may be employed for small magnitudes of change in the brightness. In certain embodiments, the relatively slow rate of change and/or the consistent time constant for small brightness changes may promote robust and smooth changes in brightness during sudden moderate changes in ambient light levels. 
       FIG. 29  depicts an embodiment where display controller  16  may modify the adjustment rate profile in response to a user input. For example, as shown in  FIGS. 3 and 7 , a user may move graphical element  56  to the right or left to increase or decrease the rate of the brightness adjustment. Accordingly, movement of graphical element  56  may scale an adjustment profile up or down. In particular, as shown in  FIGS. 3 and 7 , a user may move graphical element  56  to the left to decrease the rate of the brightness adjustment. In response to the user input, display controller  16  ( FIG. 1 ) may move the adjustment rate profile  328  down to produce a modified adjustment rate profile  342  that has a relatively slower rate of response when compared to adjustment rate profile  328 . In another example, a user may move graphical element  56  to the right to increase the rate of the brightness adjustment. In response to the user input, display controller  16  ( FIG. 1 ) may move adjustment rate profile  328  up to produce a modified adjustment rate profile  344  that has a relatively quicker rate of response when compared to adjustment rate profile  328 . 
     As shown in  FIGS. 3 and 7 , GUI  38  includes a single graphical element  56  that may be adjusted by a user to increase or decrease the response rate. However, in other embodiments, two or more graphical elements  56  may be included in GUI  38  that allow a user to set different adjustment rate profiles for different ambient light levels. For example, one graphical element  56  may be used to adjust the rate for a dim section  136  ( FIG. 8 ) of brightness adjustment profile  130 , while another graphical element may be used to adjust the rate for a bright section  134  ( FIG. 8 ) of brightness adjustment profile  130 . 
       FIG. 30  depicts a method  346  for adjusting the display brightness based on a response rate. Method  346  may begin by detecting (block  348 ) a change in the ambient light level. For example, light sensor  20  ( FIG. 1 ) may detect the current ambient light level. Display controller  16  may then compare the current light level to the previously measured ambient light level to detect a change in the ambient light level. 
     Display controller  16  may then verify (block  350 ) that the change in the ambient light level has exceeded a set duration. For example, the duration may include a period of time, such as 1 second, 5 seconds, 10 seconds, or 30 seconds, that may be exceeded before an adjustment is made to the brightness of display  12 . According to certain embodiments, the duration may be stored within storage  28 . In certain embodiments, the duration may be set to zero or may be a fraction of a second, such as one-tenth or one-twentieth of a second. Moreover, in certain embodiments, the duration may be adjusted by a user through a GUI. According to certain embodiments, the duration verification may ensure that the display brightness does not change rapidly when a user is moving through an area of changing ambient light conditions. For example, a user may be walking through a hallway with light sources disposed at various intervals and may not wish for the brightness to change as the user passes each individual light source. 
     Once the duration has been exceeded, display controller  16  may then determine (block  352 ) the magnitude of change in the ambient light level. For example, display controller  16  may compare the new ambient light level to a previously measured ambient light level to determine the direction of the change and calculate the amount of change in the ambient light level. In certain embodiments, the previously measured ambient light level may be the most recent previously detected ambient light level. However, in other embodiments, the previously measured ambient light level may correspond to the last ambient light level that was used by display controller  16  to make a brightness adjustment. 
     In certain embodiments, display controller  16  may set the newly detected ambient light level to a threshold amount if the detected ambient light level is below a minimum ambient light level or above a maximum ambient light level. For example, in certain embodiments, the operational range of the ambient light sensor may be approximately 1 to 50,000 lux, or more specifically, approximately 6 to 6,000 lux. In these embodiments, if the detected ambient light level if below 6 lux, display controller  16  may set the detected level to 6 lux. Similarly, if the detected ambient light level is above 6,000 lux, display controller  16  may set the detected level to 6,000 lux. However, in other embodiments, the maximum and minimum threshold values may vary depending on factors, such as the type ambient light sensor, the saturation point for the ambient light sensor, and/or the resolution requirements at low ambient light levels, among others. In these embodiments, the threshold value may be employed as the newly detected ambient light level. Further, in other embodiments, display controller  16  may ignore ambient light levels that are detected outside of the operational range of the ambient light sensor. 
     Display controller  16  may then verify (block  354 ) that the magnitude of change exceeds a threshold amount. In particular, the threshold amount specifies the minimum amount of change that should occur in the ambient light level in order to adjust the display brightness. If the threshold amount is not met, no brightness adjustment may be made, which may reduce fluctuation of the display brightness. In certain embodiments, the threshold amount may be a percentage of the current or previously measured ambient light level. For example, the threshold amount may be approximately 5 to 10 percent of the previously measured ambient light level. Further, in certain embodiments, the range of ambient light sensor  20  ( FIG. 1 ) may be divided into a series of steps or increments. For example, in certain embodiments, the step size may be approximately 0.1 to 1 lux, or more specifically, approximately 0.3 lux at low ambient light levels. In these embodiments, the threshold amount may be based on exceeding a number of steps. For example, in certain embodiments, the threshold amount may be 1 or 2 steps. In this example, the magnitude of change would exceed the threshold amount if the new ambient light level is at least two steps above or below the previously measured ambient light level. In yet other embodiments, the ambient light levels detected by the sensor may be directed to display controller  16  through an analog to digital (A/D) converter. In these embodiments, the threshold amount may be based on the count values provided by the A/D converter. According to certain embodiments, the threshold verification may reduce frequent brightness changes when the ambient light level is fluctuating by small amounts. 
     After verifying (block  354 ) that the ambient light change exceeds or meets the threshold, display controller  16  may determine (block  356 ) the new brightness setting based on the detected ambient light level. For example, display controller  16  may use a brightness adjustment profile, such as brightness adjustment profile  62  ( FIG. 4 ),  130  ( FIGS. 8 and 17 ), or  300  ( FIG. 26 ) to calculate the new brightness setting for the detected ambient light level. Display controller  16  may then determine (block  357 ) the change in the brightness. For example, display controller may compare the new brightness setting to current brightness level to determine the direction and amount of the change in the brightness level. 
     Based on the change in the brightness, display controller  16  may determine (block  358 ) the rate of response that should be employed to adjust the brightness. For example, display controller  16  may use an adjustment rate profile, such as adjustment rate profile  328  shown in  FIG. 28 , to determine the adjustment rate based on the change in the brightness level. In certain embodiments, display controller  16  may use adjustment rate profile  328  to determine an adjustment rate that corresponds to the magnitude and direction of change in the brightness. In other embodiments, display controller  16  may determine a time constant (i.e. how long it should take to complete the brightness change) based on the magnitude and the direction of change. For example, display controller  16  may use algorithms or look up tables to select and/or determine the time constant based on the change in brightness. Display controller  16  may then use the selected time constant to determine the rate of change. As discussed above with respect to  FIG. 28 , the adjustment rate may depend on both the direction of change and the amount of change. For example, a higher rate may be employed to increase the brightness than is used to reduce the brightness. Further, in certain embodiments, for relatively small changes in brightness, a set time constant or rate of change may be employed, regardless of the direction of the change. After the brightness has been determined, display controller  16  may then adjust (block  360 ) the brightness. For example, display controller  16  may vary the current or voltage supplied to backlight  14  to set the brightness to the determined brightness setting. 
     As described above with respect to  FIG. 30 , display controller  16  may verify (block  354 ) that the amount of change in ambient light exceeds a certain threshold prior to making a brightness change. According to certain embodiments, the threshold may be a set amount of change in an ambient light level, a step size, or a count level, or may be based on a percentage of the ambient light level. Further, as described below with respect to  FIG. 31 , in certain embodiments, the threshold for making a brightness adjustment may be selected based on whether display controller  16  is currently making a brightness adjustment. According to certain embodiments, display controller  16  may select between a threshold amount of change in the ambient light level and a threshold amount of change in the brightness. For example, a threshold amount of change in the ambient light level may be employed when the backlight is currently transitioning to a new brightness level, while a threshold amount of change in the brightness may be employed when the backlight is operating at a steady brightness level. According to certain embodiments, employing different thresholds depending on the operational state of the backlight may inhibit interruption of a current brightness adjustment. For example, employing an ambient light threshold during current brightness changes may ensure that a large enough ambient light level change is detected, for example 15 to 20 percent, before interrupting a current brightness change. The ambient light threshold may be particularly useful during longer adjustment periods, such as dimming of the backlight, which may take approximately 5 to 30 seconds, or longer. 
       FIG. 31  depicts an embodiment of a method  362  for verifying whether a brightness change should be made. Method  362  may begin by determining (block  364 ) the state of the brightness adjustment. For example, display controller  16  may determine whether a brightness adjustment is currently being conducted or whether the brightness is at steady state. 
     Display controller  16  may then select (block  366 ) a threshold based on the adjustment state. For example, display controller  16  may select between an ambient light threshold and a brightness threshold. The ambient light threshold specifies a minimum amount of change between the newly detected ambient light level and a previous ambient light level, while the brightness threshold specifies a minimum amount of change between the current brightness and a target brightness that corresponds to the newly detected ambient light level. The ambient light threshold may be selected if a brightness adjustment is in progress, while the brightness threshold may be selected if no brightness adjustment is in progress. 
     Display controller  16  may then determine (block  368 ) whether the selected threshold has been exceeded. For example, display controller  16  may determine an amount of change that corresponds to the selected threshold. In particular, the threshold amount of change specifies a minimum amount of change that is needed to perform a brightness adjustment. According to certain embodiments, display controller  16  may determine the threshold amount based on one or more algorithms, lookup tables, or the like. Further, in certain embodiments, display controller  16  may retrieve the selected threshold amount from storage  28 . 
     Display controller  16  may then compare the current change to the threshold amount to determine (block  368 ) whether the selected threshold has been exceeded. For example, when the ambient light threshold is selected, display controller  16  may compare the newly detected ambient light level to a previously detected ambient light level to determine the current change. In certain embodiments, the previously detected ambient light level may be the most recent previously detected ambient light level. However, in other embodiments, the previously measured ambient light level may correspond to the last ambient light level that was used by display controller  16  to make a brightness adjustment. When the brightness threshold is selected, display controller  16  may compare the current brightness setting to a target brightness setting that corresponds to the newly detected ambient light level to determine the current change. For example, display controller  16  may employ a brightness adjustment profile  130  ( FIG. 8 ) to determine the target brightness setting. 
     Display controller  16  may then determine whether the current change exceeds the threshold amount of change. For example, display controller  16  may compare the change in the ambient light level or the brightness to the selected ambient light threshold amount of change or brightness threshold amount of change, respectively. According to certain embodiments, the ambient light threshold amount of change may be approximately 15 to 20 percent of the current ambient light level. Further, according to certain embodiments, the brightness threshold amount may be approximately 10 percent of the current brightness. If the change exceeds the selected threshold amount, display controller  16  may then perform (block  370 ) a change to the display brightness based on the detected ambient light level. For example, display controller may determine (block  356 ) the adjustment rate, determine (block  358 ) the new brightness level, and then adjust (block  360 ) the display brightness, as described above with respect to  FIG. 30 . 
     On the other hand, if display controller  16  determines (block  368 ) that the selected threshold is not exceeded, display controller  16  may continue (block  374 ) with its current state of operation. For example, if a brightness adjustment was in progress prior to detecting a new ambient light level, display controller  16  may continue to make the present brightness adjustment. If no brightness adjustment was in progress, display controller  16  may continue to operate the display at the present brightness level. 
     In addition to, or instead of, adjusting the brightness based on detected ambient light levels, electronic device  10  may adjust the brightness of display  12  based on the angular incidence of ambient light hitting display  12 . In certain embodiments, as described below with respect to  FIG. 33 , electronic device  10  may include one or more ambient light sensors designed to compensate for the angular incidence of ambient light hitting display  12 . In these embodiments, the ambient light sensors may perceive the ambient light levels differently depending on the angular incidence of the ambient light. In other embodiments, as described below with respect to  FIGS. 34 to 35 , electronic device  10  may detect the angle of incidence of the ambient light and may adjust the received ambient light level to compensate for the angle of incidence of the ambient light. 
       FIG. 32  depicts an environment  376  where an electronic device  10  may be employed. For example, environment  376  may include an electronic device  10 B, shown here as a multifunctional media player. According to certain embodiments, electronic device  10 B may be a model of an iPhone® available from Apple Inc. However, in other embodiments, the electronic device may be a laptop computer, such as electronic device  10 A shown in  FIG. 2 , or any other suitable electronic device. 
     Environment  376  also includes an ambient light source  378 . Ambient light source  378  may provide ambient light for viewing electronic device  10 B and its associated display  12 B. One or more light sensors  20 B within electronic device  10 B may detect the angle of ambient light from ambient light source  378 . Ambient light source  378  may be moved between positions  380 ,  382 , and  384 , as generally indicated by an arrow  222 . According to certain embodiments, ambient light source  378  may be any suitable ambient light source, such as the sun, a lamp, or a flashlight, among others. 
     In the first position  380 , ambient light source  378  may direct light towards display  12 B in a first direction  224 , which may correspond generally to an angle of incidence of 0°. Ambient light source  378  and/or electronic device  10 B may be moved with respect to one another to change the position  380  and the angle of incidence of the ambient light source  378  with respect to display  12 B of electronic device  10 B. For example, in the second position  382 , light source  378  may direct light towards display  12 B in a direction  228 , which may correspond to an angle of incidence of approximately 45°. In another example, in the third position  384 , light source  378  may direct light towards display  12 B in a third direction  232 , which may correspond to an angle of incidence of approximately −45°. In certain embodiments, light sensor  20 B within electronic device  10 B may perceive the ambient light level differently depending on the angle of incidence  226 ,  230 , or  234 . In other embodiments, light sensor  20 B may be designed to detect the angle of incidence  226 ,  230 , or  234  and the actual ambient light level. In these embodiments, electronic device  10 B may employ one or more angular adjustment profiles to adjust the detected ambient light level based on the detected angle of incidence. 
       FIG. 33  is a chart  386  depicting an embodiment of a response profile  388  for an ambient light sensor designed to perceive ambient light levels differently based on the angle of incidence of the ambient light. Chart  386  includes an x-axis  390  that represents the angle of incidence of ambient light source  378  ( FIG. 32 ). Chart  236  also includes a y-axis  392  that represents the ambient light level. Line  394  represents the actual ambient light level emitted by ambient light source  378 , for example, as may be measured by a lux meter. As shown on chart  386 , the actual ambient light level, represented by straight line  394 , remains constant as the angle of incidence of ambient light source  378  changes. 
     Response profile  388  represents the ambient light level perceived by ambient light sensor  20 . As shown, response profile  388  is a symmetrical curve about point  396  where line  394  intersects response profile  388 . Point  396  is located along x-axis  392  at 0°. Accordingly, when the angle of incidence of the ambient light source is 0°, the perceived ambient light level may be approximately equal to the actual ambient light level. As shown, response profile  388  generally corresponds to a cosine curve, which as may be appreciated by those skilled in the art, may model the reflection of ambient light off of flat surfaces in the real world. Accordingly, the perceived ambient light level may be approximately equal to the actual ambient light level multiplied by the cosine of the angle of incidence. The perceived ambient light levels, represented by response profile  388 , may be provided to display controller  16  and used to adjust the brightness of display  12  based on ambient light levels, as described above with respect to  FIGS. 3 to 30 . Accordingly, by designing ambient light sensor  20  to perceive ambient light levels in accordance with a cosine curve, the brightness of the display may be adjusted in a manner that models the reflective behavior of physical surfaces. 
     Line  394  and response profile  388  divide chart  386  into area  398  located between line  394  and response profile  388  and an area  400  located between response profile  388  and x-axis  392 . In other embodiments, the curvature of response profile  388  may widen until response profile  388  approaches line  394 . In particular, the curvature of response profile  388  may be modified so that response profile  388  is disposed anywhere in area  398  up to and along line  394 . 
     As may be appreciated by those skilled in the art, optical elements may be employed to design ambient light sensor  20  to produce response profile  388 . For example, in certain embodiments, ambient light sensor  20  may include optical elements, such as a diffuser cover, a light window, and/or a fiber optic light pipe, among others. The shape, size, geometry, and/or structural materials of these elements may be varied to produce the desired response profile  388 . 
     In other embodiments, rather than designing ambient light sensor  20  to perceive ambient light different based on the angle of incidence of the ambient light source, ambient light sensor  20  may be designed to detect the actual ambient light level. In these embodiments, display controller  16  may be designed to apply an adjustment to the actual ambient light level to account for the angle of incidence using one or more angular adjustment profiles. 
       FIG. 34  is a chart  402  depicting an embodiment of an angular adjustment profile  404  for modifying the detected ambient light level based on the angle of incidence of an ambient light source. Line  406  represents the ambient light level perceived by ambient light sensor  20 , which, as may be seen by comparing  FIGS. 33 and 34 , is approximately equal to the actual ambient light level  394  ( FIG. 33 ). Angular adjustment profile  404  represents an adjustment that may be made to the ambient light level detected by light sensor  20  ( FIG. 1 ). In particular, the detected ambient light level, represented by line  406 , may be multiplied by the cosine of the detected angle of incidence to produce angular adjustment profile  404 . The adjusted ambient light level, corresponding to angular adjustment profile  404 , may then be used to determine a brightness level using a brightness adjustment profile as described above with respect to  FIGS. 3 to 31 . 
     As shown in  FIG. 34 , angular adjustment profile  404  generally corresponds to a cosine curve, and accordingly, may model the reflection of ambient light off of flat surfaces in the real world. In other embodiments, the curve of angular adjustment profile  404  may be widened. For example, angular adjustment profile  404  may be widened until angular adjustment profile approaches line  406 . In particular, the curvature of response profile  404  may be modified so that angular adjustment profile  404  is disposed anywhere in area  408 , which is defined as the space between angular adjustment profile  404  and line  406 . According to certain embodiments, angular adjustment profile  404  may be designed to simulate the reflectivity of a hard copy material, as described above with respect to  FIG. 7 . For example, the shape of angular adjustment profile  404  may be designed to simulate the reflectivity of a book or a newspaper, which may be selected by a user through graphical elements  114  and  116 , respectively. 
     Angular adjustment profile  404  also may be employed to adjust ambient light levels detected from multiple ambient light sources. In these embodiments, the ambient light levels from each light source may be weighted based on their relative brightness and adjusted using one or more angular adjustment profiles. The adjusted ambient light levels may be then combined to determine a total adjustment ambient light level, which may be used to determine the brightness for display  12 , as described above with respect to  FIGS. 3 to 31 . Further, in other embodiments, rather than determining an adjusted ambient light level that can be used to determine a brightness for the display, the display brightness may first be determined using the actual ambient light level, for example, as shown in  FIG. 34  by line  406 . An adjustment profile may then be used to modify the determined brightness level to account for the angle of incidence of the ambient light source. 
       FIG. 35  depicts a method  412  for adjusting the brightness of a display based on an angle of incidence of an ambient light source. Method  412  may begin by verifying (block  414 ) enablement of the angular adjustment. For example, as shown in  FIG. 7 , a user may check box  124  to disable an angular adjustment. If box  124  is unchecked, the angular adjustment may be enabled. Display controller  16  may then determine (block  416 ) the appropriate angular adjustment profile to use in making the angular adjustment. For example, processor  18  may provide a signal to display controller  16  indicating that graphical element  114  or  116  ( FIG. 7 ) was selected by a user through GUI  38 . Display controller  16  may then retrieve the appropriate reflectivity adjustment profile  404  associated with the user input. 
     Electronic device  10  may then detect (block  418 ) the angle of incidence of the ambient light source. For example, as shown in  FIG. 32 , when ambient light source  378  is in the second position  382 , electronic device  10  may detect that the angle of incidence is approximately 45°. According to certain embodiments, ambient light sensor  20  may include an array of sensors mapped on a spherical surface that are designed to detect the distribution of ambient light. The distribution information from ambient light sensor  20  may be provided to display controller  16  to determine the angle of incidence of the ambient light. In another example, ambient light sensor  20  may be used in conjunction with camera  27  ( FIG. 1 ) to determine the angle of incidence of the ambient light source. In other embodiments, electronic device  10  may include at least two ambient light sensors  20 , disposed on opposite surfaces of electronic device  10 , that may be used to determine the angle of incidence of the ambient light. Further, in certain embodiments, electronic device  10  may detect multiple angles of incidence, for example, when there are two or more ambient light sources. 
     Method  412  may then continue by determining (block  256 ) the angular adjustment. For example, display controller  16  may use an angular adjustment profile  404 , as described above with respect to  FIG. 34 , to determine the adjusted ambient light level. In certain embodiments, display controller  16  may calculate the adjusted ambient light level using the angular adjustment profile. For example, in certain embodiments, display controller  16  may calculate the adjusted ambient light level by multiplying the detected ambient light level by the cosine of the angle of incidence of the ambient light source. Further, in certain embodiments, display controller  16  may calculate the adjusted ambient light level for multiple light sources that have different angles of incidence. For example, in certain embodiments, display controller  16  may weight each of the light sources based on their corresponding ambient light level and/or angle of incidence. According to certain embodiments, display controller  16  may employ one or more algorithms to calculate the angular adjustment and/or the adjusted ambient light level. Further, in certain embodiments, the angular adjustment profile may be represented by one or more algorithms. 
     After determining the adjusted ambient light level, display controller  16  may then adjust (block  422 ) the brightness of display  12 . For example, display controller  16  may use the adjusted ambient light level in conjunction with brightness adjustment profiles  62  ( FIG. 4 ),  130  ( FIGS. 8 and 17 ), or  300  ( FIG. 26 ) to determine a brightness level for display  12 . Display controller  16  may then vary the current or voltage supplied to backlight  14  to achieved the determined brightness level. Display controller  16  also may adjust the brightness of display  12  at a rate determined using method  346  as described above with respect to  FIG. 30 . 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20100930
Publication Date: 20141111
Grant Date: 20141111
Priority Date: 20100726
Inventors: BARNHOEFER ULRICH T.
CHEN WEI
BAE HOPIL
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05B41/3922", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05B41/3922", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05B33/0851", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04N5/57", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/36", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05B45/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B41/3922", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05B45/12", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 45493059