PATENT DOCUMENT

Publication Number: US-9741305-B2
Application Number: US-201514818001-A
Country: US
Kind Code: B2

Title: Devices and methods of adaptive dimming using local tone mapping

Abstract:
Methods, systems, and devices for improving contrast, dynamic range, and power consumption of a backlight in a display are provided. By way of example, a method includes receiving image data to be displayed on pixels of a display panel, generating a global histogram of the image data, generating a plurality of thresholds based on the global histogram, and defining a first threshold and a second threshold of the plurality of thresholds as local thresholds based on the global histogram and a local histogram. The first threshold and the second threshold are generated according to a local tone mapping function. The method further includes adjusting a luminance of one or more of pixels of the display panel based at least in part on the first threshold and the second threshold.

Claims:
What is claimed is: 
     
       1. A method, comprising:
 receiving image data to be displayed on pixels of a display panel; 
 generating a global histogram of the image data; 
 generating a plurality of thresholds based on the global histogram, wherein generating the plurality of thresholds comprises generating a first global threshold, a second global threshold, and a third global threshold; 
 defining a first threshold and a second threshold of the plurality of thresholds as local thresholds based on the global histogram and a local histogram, wherein the first threshold and the second threshold are generated according to a local tone mapping function and each is based at least in part on a respective threshold of the plurality of thresholds; and 
 adjusting a luminance of one or more of pixels of the display panel based at least in part on the first threshold and the second threshold. 
 
     
     
       2. The method of  claim 1 , wherein generating the third global threshold comprises generating a lower limit of the luminance adjustment. 
     
     
       3. The method of  claim 2 , wherein adjusting the luminance of the one or more pixels comprises adjusting the luminance of one or more of pixels having a luminance greater than the lower limit of the luminance adjustment. 
     
     
       4. The method of  claim 1 , wherein defining the first threshold comprises defining an upper limit of a dynamic range of a segment of the pixels. 
     
     
       5. The method of  claim 1 , wherein defining the second threshold comprises defining a lower limit of a dynamic range of a segment of the pixels. 
     
     
       6. The method of  claim 1 , wherein adjusting the luminance of the one or more pixels comprises increasing the luminance and preserving a local contrast of the one or more pixels. 
     
     
       7. A system, comprising:
 a display panel comprising an array of pixels configured receive pixel data signals; and 
 a processor configured to: 
 generate a first local threshold and a second local threshold based on a plurality of global thresholds, wherein the first local threshold and the second local threshold are generated based at least in part on local tone mapping function and respective global thresholds of the plurality of global thresholds; 
 adjust a luminance parameter of the pixel data signals based at least in part on the first local threshold and the second local threshold; and 
 supply the adjusted pixel data signals to the display panel. 
 
     
     
       8. The system of  claim 7 , wherein the plurality of global thresholds comprises a first global threshold, a second global threshold, and a third global threshold, and wherein the first local threshold and the second local threshold are generated based at least in part on a local tone mapping function of the first global threshold and the second global threshold, respectively. 
     
     
       9. The system of  claim 8 , wherein the third global threshold comprises a lower limit by which to adjust the luminance parameter of the pixel data signals. 
     
     
       10. The system of  claim 9 , wherein the processor is configured to generate a contrast preservation matrix based on the first local threshold and the second local threshold, wherein the preservation matrix is configured to adjust the luminance of pixels above the lower limit while the luminance of pixels below the lower limit are unadjusted. 
     
     
       11. The system of  claim 10 , wherein the processor is configured to generate the contrast preservation matrix based on a histogram analysis of a luminance of each subpixel of the pixels. 
     
     
       12. The system of  claim 8 , wherein the first local threshold, the second local threshold, and the third global threshold are configured to define vertical segments of pixels or light sources of the display panel, and wherein the processor is configured adjust the luminance parameter of the pixel data signals comprising a luminance level beyond the third global threshold. 
     
     
       13. The system of  claim 8 , wherein the first local threshold, the second local threshold, and the third global threshold are configured to define horizontal segments of pixels or light sources of the display panel, and wherein the processor is configured adjust the luminance parameter of the pixel data signals comprising a luminance level between the first local threshold and the second local threshold. 
     
     
       14. The system of  claim 7 , wherein the first local threshold comprises an upper limit of a dynamic range of a segment of pixels of the display panel. 
     
     
       15. The system of  claim 7 , wherein the second local threshold comprises a lower limit of a dynamic range of a segment of pixels of the display panel. 
     
     
       16. A method for controlling a backlight of an electronic display, comprising:
 receiving pixel data; 
 generating a first histogram based on the pixel data; 
 generating a first set of threshold values based on the first histogram, wherein a first threshold value and a second threshold value of the first set of threshold values are configured to represent a local upper limit of a dynamic range of the pixel data and a local lower limit of the dynamic range of the pixel data, respectively, based at least in part on a second histogram of the pixel data and a second set of threshold values for global image data containing the pixel data; 
 modifying a brightness value of a set of pixels having a brightness value between the local upper limit and the local lower limit, wherein modifying the brightness value of the set of pixels comprises increasing the brightness value of a first subset of the set of pixels while preserving the brightness value of a second subset of the set of pixels; and 
 adjusting an intensity of at least a portion of the backlight of the electronic display based on the modified brightness value of the set of pixels. 
 
     
     
       17. The method of  claim 16 , wherein modifying the brightness value of the set of pixels comprises reducing a possibility of halo artifacts, clipping artifacts, or a combination thereof, from becoming apparent on the electronic display. 
     
     
       18. The method of  claim 16 , wherein modifying the brightness value of the set of pixels comprises reducing a power consumption of the electronic display. 
     
     
       19. The method of  claim 16 , wherein modifying the brightness value of the set of pixels comprises increasing a contrast ratio of the electronic display. 
     
     
       20. An electronic device, comprising:
 a memory device configured to store one or more adaptive dimming components; and 
 a graphics processing unit (GPU) configured to execute the one or more adaptive dimming components, wherein the one or more adaptive dimming components comprises: 
 a global component configured to generate a first global threshold:  _ 1 , a second global threshold:  _ 2 , and a third global threshold:  _ 3  based on incoming image data; 
 a local component configured to receive the global thresholds  _ 1 ,  _ 2 , and  _ 3  from the global component, and to generate a first local threshold based on the first global threshold:  _ 1  and a second local threshold based on the second global threshold:  _ 2 ; and 
 a pixel manipulation component configured to receive the global thresholds  _ 1 ,  _ 2 , and  _ 3 , the first local threshold, and the second local threshold, and to adjust a brightness of one or more segments of pixels of the image data based at least in part on the global thresholds  _ 1 ,  _ 2 , and  _ 3 , the first local threshold, and the second local threshold. 
 
     
     
       21. The electronic device of  claim 20 , wherein the pixel manipulation component is configured to adjust the brightness of the one or more segments of pixels by increasing a brightness level of a first set of pixels while preserving a brightness level of a second set of pixels neighboring the first set of pixels. 
     
     
       22. The electronic device of  claim 20 , wherein the local component is configured to calculate a risk value indicative of likelihood of image artifacts based at least in part on the global thresholds  _ 1 ,  _ 2 , and  _ 3 , the first local threshold, and the second local threshold. 
     
     
       23. The electronic device of  claim 22 , wherein the global component or the local component is configured to supply the risk value to the pixel manipulation component. 
     
     
       24. The electronic device of  claim 20 , wherein the global component is configured to adjust a temporal component of the global thresholds  _ 1 ,  _ 2 , and  _ 3  before supplying the global thresholds  _ 1 ,  _ 2 , and  _ 3  to the pixel manipulation component. 
     
     
       25. The electronic device of  claim 20 , wherein the local component is configured to adjust a spatial component of the first local threshold and the second local threshold before supplying the first local threshold and the second local threshold to the pixel manipulation component. 
     
     
       26. The electronic device of  claim 20 , wherein the GPU is configured to execute the one or more adaptive dimming components frame by frame, wherein a brightness of each frame of pixels is adjusted based at least in part on the global thresholds  _ 1 ,  _ 2 , and  _ 3 , the first local threshold, and the second local threshold of each preceding frame of pixels. 
     
     
       27. The electronic device of  claim 20 , wherein the pixel manipulation component is configured to supply the adjusted one or more segments of pixels to pixels of a display. 
     
     
       28. The electronic device of  claim 20 , comprising a display configured to display the image data. 
     
     
       29. A non-transitory computer-readable medium having computer executable code stored thereon, the code comprising instructions to:
 cause a processor to receive image data to be displayed on pixels of a display panel; 
 cause the processor to generate a global histogram of the image data; 
 cause the processor to generate a plurality of thresholds based on the global histogram; 
 cause the processor to define a first threshold and a second threshold as local thresholds based at least in part on the plurality of thresholds, the global histogram, and a local histogram; and 
 cause the processor to adjust a luminance of one or more of pixels of the display panel based at least in part on the first threshold and the second threshold.

Description:
BACKGROUND 
     This disclosure relates to increasing image pixel brightness values while lowering backlight intensity, thereby saving power while reducing the possibility of image artifacts. 
     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. 
     Liquid crystal displays (LCDs) are commonly used as screens or displays for a wide variety of electronic devices, including such consumer electronics as televisions, computers, and handheld devices (e.g., cellular telephones, audio and video players, gaming systems, and so forth). Such LCD devices typically provide a flat display in a relatively thin package that is suitable for use in a variety of electronic goods. In addition, such LCD devices typically use less power than comparable display technologies, making them suitable for use in battery-powered devices or in other contexts where it is desirable to minimize power usage. 
     Often, some LCDs may employ certain dimming techniques to improve contrast and dynamic range in the LCDs. However, these dimming techniques may have limited power saving capability, and may further engender the possibility of clipping artifacts becoming apparent on the LCD. For example, in displayable images including a transition from darker image content to brighter image content may produce backlight flashing artifacts or washed-out pixels, which may be both apparent and undesirable to a user. It may be useful to provide more advanced dimming techniques. 
     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. 
     Various embodiments of the present disclosure relate to methods, systems, and devices for improving contrast and dynamic range and reducing the power of the backlight in liquid crystal displays (LCDs). By way of example, a method includes receiving image data to be displayed on pixels of a display panel, generating a global histogram of the image data, generating a plurality of thresholds based on the global histogram, and defining a first threshold and a second threshold of the plurality of thresholds as local thresholds based on the global histogram and a local histogram. The first threshold and the second threshold are generated according to a local tone mapping function. The method further includes adjusting a luminance of one or more of the pixels of the display panel based at least in part on the first threshold and the second threshold. By reducing the backlight while also preserving local contrast, substantial power may be saved while avoiding the appearance of display artifacts. 
     Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
       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 schematic block diagram of an electronic device including a display, in accordance with an embodiment; 
         FIG. 2  is a perspective view of a notebook computer representing an embodiment of the electronic device of  FIG. 1 ; 
         FIG. 3  is a front view of a hand-held device representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 4  is a front view of another hand-held device representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 5  is a front view of a desktop computer representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 6  is an equivalent circuit diagram of the display of  FIG. 1  including an adaptive dimming component, in accordance with an embodiment; 
         FIG. 7  is a process illustrative of the operation of the adaptive dimming component of  FIG. 6 , in accordance with an embodiment; 
         FIG. 8  is an example of the present adaptive dimming techniques, in accordance with an embodiment; 
         FIG. 9  illustrates one or more computational blocks that may be included as part of the adaptive dimming component of  FIG. 6 , in accordance with an embodiment; 
         FIG. 10  illustrates an example of a cross section pixel map, in accordance with an embodiment; 
         FIG. 11  is a plot diagram illustrating an example of a global and local histogram, global partial image data, and global full image data, in accordance with an embodiment; 
         FIG. 12  is a plot diagram illustrating an example of a pixel map or a local histogram of a horizontal segments of pixels of the display of  FIG. 1 , in accordance with an embodiment; 
         FIGS. 13A-13G  display examples of the present adaptive dimming techniques with local tone mapping, in accordance with an embodiment; 
         FIG. 14  illustrates a detailed embodiment of the adaptive dimming component of  FIG. 6 , in accordance with an embodiment; 
         FIG. 15  illustrates another detailed embodiment of the adaptive dimming component of  FIG. 6 , in accordance with an embodiment; 
         FIG. 16  illustrates a detailed embodiment of the adaptive dimming component of  FIG. 6  including risk analysis with temporal integration, in accordance with an embodiment; 
         FIG. 17  illustrates another detailed embodiment of the adaptive dimming component of  FIG. 6  including risk analysis and vertical blanking adjustments, in accordance with an embodiment; 
         FIG. 18  is a flow diagram, illustrating an embodiment of an adaptive dimming process useful in reducing image errors and power consumption while providing a high contrast ratio, in accordance with an embodiment; and 
         FIG. 19  illustrates simulation examples of images generated using the presently disclosed adaptive dimming with local tone mapping techniques, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. These described embodiments are only examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be 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. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     Embodiments of the present disclosure relate to methods, systems, and devices for improving contrast and dynamic range and reducing the power of the backlight in liquid crystal displays (LCDs). Indeed, the present embodiments may include an adaptive dimming technique utilizing a local tone mapping function. In certain embodiments, the present adaptive dimming techniques may include receiving pixel data, and generating a global histogram based on the pixel data. The adaptive dimming technique may further include defining global thresholds (e.g., global backlight thresholds). For example, based on the global histogram, three thresholds (e.g., BL 1 , BL 2 , and BL 3 ), as well as the target backlight brightness level, may be defined and generated. In certain embodiments, the global backlight levels BL 1  and BL 2  may be then locally adapted based on the global values and a local histogram (e.g., based on a local segment of pixels) and local tone mapping function. Lastly, based on the locally adapted backlight levels BL 1  and BL 2  and the global backlight level BL 3 , incoming pixel data may be modified to increasing the brightness values of some of the pixels while preserving local contrast between the modified pixels and neighboring pixels. In this way, the present adaptive dimming techniques with local tone mapping may reduce possible image errors (e.g., clipping errors, halo artifacts, and so forth) and power consumption while providing a high contrast ratio. 
     With the foregoing in mind, a general description of suitable electronic devices that may include a display and data processing circuitry useful in improving contrast and dynamic range and reducing the power of the backlight in liquid crystal displays (LCDs). Turning first to  FIG. 1 , an electronic device  10  according to an embodiment of the present disclosure may include, among other things, one or more processor(s)  12 , memory  14 , nonvolatile storage  16 , a display  18  input structures  22 , an input/output (I/O) interface  24 , network interfaces  26 , and a power source  28 . 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 be noted that  FIG. 1  is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in electronic device  10 . 
     By way of example, the electronic device  10  may represent a block diagram of the notebook computer depicted in  FIG. 2 , the handheld device depicted in  FIG. 3 , the desktop computer depicted in  FIG. 4 , the wearable electronic device depicted in  FIG. 5 , or similar devices. It should be noted that the processor(s)  12  and/or other data processing circuitry may be generally referred to herein as “data processing circuitry.” Such data processing circuitry may be embodied wholly or in part as software, firmware, hardware, or any combination thereof. Furthermore, the data processing circuitry may be a single contained processing module or may be incorporated wholly or partially within any of the other elements within the electronic device  10 . 
     In the electronic device  10  of  FIG. 1 , the processor(s)  12  and/or other data processing circuitry may be operably coupled with the memory  14  and the nonvolatile memory  16  to perform various algorithms. Such programs or instructions executed by the processor(s)  12  may be stored in any suitable article of manufacture that includes one or more tangible, computer-readable media at least collectively storing the instructions or routines, such as the memory  14  and the nonvolatile storage  16 . The memory  14  and the nonvolatile storage  16  may include any suitable articles of manufacture for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. Also, programs (e.g., an operating system) encoded on such a computer program product may also include instructions that may be executed by the processor(s)  12  to enable the electronic device  10  to provide various functionalities. 
     In certain embodiments, the display  18  may be a liquid crystal display (LCD), which may allow users to view images generated on the electronic device  10 . In some embodiments, the display  18  may include a touch screen, which may allow users to interact with a user interface of the electronic device  10 . Furthermore, it should be appreciated that, in some embodiments, the display  18  may include one or more organic light emitting diode (OLED) displays, or some combination of LCD panels and OLED panels. Further, in some embodiments, the display  18  may include a light source (e.g., backlight) that may be used to emit light to illuminate displayable images on the display  18 . Indeed, in some embodiments, as will be further appreciated, the light source (e.g., backlight) may include any type of suitable lighting device such as, for example, cold cathode fluorescent lamps (CCFLs), hot cathode fluorescent lamps (HCFLs), and/or light emitting diodes (LEDs), or other light source that may be utilize to provide highly backlighting. 
     The input structures  22  of the electronic device  10  may enable a user to interact with the electronic device  10  (e.g., pressing a button to increase or decrease a volume level). The I/O interface  24  may enable electronic device  10  to interface with various other electronic devices, as may the network interfaces  26 . The network interfaces  26  may include, for example, interfaces for a personal area network (PAN), such as a Bluetooth network, for a local area network (LAN) or wireless local area network (WLAN), such as an 802.11x Wi-Fi network, and/or for a wide area network (WAN), such as a 3 rd  generation (3G) cellular network, 4 th  generation (4G) cellular network, or long term evolution (LTE) cellular network. The network interface  26  may also include interfaces for, for example, broadband fixed wireless access networks (WiMAX), mobile broadband Wireless networks (mobile WiMAX), asynchronous digital subscriber lines (e.g., ADSL, VDSL), digital video broadcasting-terrestrial (DVB-T) and its extension DVB Handheld (DVB-H), ultra Wideband (UWB), alternating current (AC) power lines, and so forth. 
     In certain embodiments, the electronic device  10  may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. Such computers may include computers that are generally portable (such as laptop, notebook, and tablet computers) as well as computers that are generally used in one place (such as conventional desktop computers, workstations and/or servers). In certain embodiments, the electronic device  10  in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way of example, the electronic device  10 , taking the form of a notebook computer  30 A, is illustrated in  FIG. 2  in accordance with one embodiment of the present disclosure. The depicted computer  30 A may include a housing or enclosure  32 , a display  18 , input structures  22 , and ports of an I/O interface  24 . In one embodiment, the input structures  22  (such as a keyboard and/or touchpad) may be used to interact with the computer  30 A, such as to start, control, or operate a GUI or applications running on computer  30 A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on display  18 . 
       FIG. 3  depicts a front view of a handheld device  30 B, which represents one embodiment of the electronic device  10 . The handheld device  34  may represent, for example, a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. By way of example, the handheld device  34  may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. 
     The handheld device  30 B may include an enclosure  36  to protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure  36  may surround the display  18 , which may display indicator icons  39 . The indicator icons  39  may indicate, among other things, a cellular signal strength, Bluetooth connection, and/or battery life. The I/O interfaces  24  may open through the enclosure  36  and may include, for example, an I/O port for a hard wired connection for charging and/or content manipulation using a standard connector and protocol, such as the Lightning connector provided by Apple Inc., a universal service bus (USB), or other similar connector and protocol. 
     User input structures  42 , in combination with the display  18 , may allow a user to control the handheld device  30 B. For example, the input structure  40  may activate or deactivate the handheld device  30 B, the input structure  42  may navigate user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device  30 B, the input structures  42  may provide volume control, or may toggle between vibrate and ring modes. The input structures  42  may also include a microphone may obtain a user&#39;s voice for various voice-related features, and a speaker may enable audio playback and/or certain phone capabilities. The input structures  42  may also include a headphone input may provide a connection to external speakers and/or headphones. 
       FIG. 4  depicts a front view of another handheld device  30 C, which represents another embodiment of the electronic device  10 . The handheld device  30 C may represent, for example, a tablet computer, or one of various portable computing devices. By way of example, the handheld device  30 C may be a tablet-sized embodiment of the electronic device  10 , which may be, for example, a model of an iPad® available from Apple Inc. of Cupertino, Calif. 
     Turning to  FIG. 5 , a computer  30 D may represent another embodiment of the electronic device  10  of  FIG. 1 . The computer  30 D may be any computer, such as a desktop computer, a server, or a notebook computer, but may also be a standalone media player or video gaming machine. By way of example, the computer  30 D may be an iMac®, a MacBook®, or other similar device by Apple Inc. It should be noted that the computer  30 D may also represent a personal computer (PC) by another manufacturer. A similar enclosure  36  may be provided to protect and enclose internal components of the computer  30 D such as the display  18 . In certain embodiments, a user of the computer  30 D may interact with the computer  30 D using various peripheral input devices, such as the input structures  22  or mouse  38 , which may connect to the computer  30 D via a wired and/or wireless I/O interface  24 . 
     In certain embodiments, as previously noted above, each embodiment (e.g., notebook computer  30 A, handheld device  30 B, handheld device  30 C, computer  30 D) of the electronic device  10  may include a display  18 , which may include a light source (e.g., backlight) that may be used to emit light to illuminate displayable images on the display  18 . Indeed, as may be appreciated, the display  18  may be employed to render images (e.g., still images, video images, multi-media images, and so forth) to a user of the electronic device with high performance. Thus, it may be useful to monitor and adjust the operating parameters (e.g., contrast, luminance, color, viewing angle, brightness, sharpness, and so forth) of the backlight of the display  18 . Indeed, as will be further appreciated with respect to  FIGS. 6-17 , in order to attenuate backlight brightness (e.g., luminance), increase global and local contrast of images displayed on the display  18 , improve dynamic contrast, and reduce power consumption of the backlight of the display  18 , it may be useful to provide one or more adaptive dimming techniques with a local tone mapping function to modulate and control the light source (e.g., backlight) of the display  18 . 
     Turning now to  FIG. 6 , which generally represents an equivalent circuit diagram of, for example, the TFT layer of the display  18  in accordance with some embodiments. In particular, the display  18  may include a pixel array  100 . As illustrated, the pixel arrays  100  may include a number of unit pixels  102  disposed in pixel array or matrix. In these arrays, each unit pixel  102  may be defined by the intersection of rows and columns, represented by gate lines  104  (also referred to as scanning lines) and data lines  106  (also referred to as data lines), respectively. Although only  6  unit pixels  102 , referred to individually by the reference numbers  102   a - 102   f , respectively, are shown for purposes of simplicity, it should be understood that in an actual implementation, each of the data lines  106  and the gate lines  104  may include hundreds or thousands of such unit pixels  102 . Each of the unit pixels  102  may represent one of three subpixels that respectively filter only one color (e.g., red, blue, or green (RGB)) of light through, for example, a color filter. For purposes of the present disclosure, the terms “pixel,” “subpixel,” and “unit pixel” may be used largely interchangeably. 
     In the presently illustrated embodiment, each unit pixel  102  may include a thin film transistor (TFT)  108  for switching a data signal stored on a respective pixel electrode  110 . The potential stored on the pixel electrode  110  relative to a potential of a common electrode  112  (e.g., creating a liquid crystal capacitance C LC ), which may be shared by other pixels  102 , may generate an electrical field sufficient to alter the arrangement of liquid crystal molecules (not illustrated in  FIG. 6 ). In the depicted embodiment of  FIG. 6 , a source  114  of each TFT  108  may be electrically connected to a data line  106  and a gate  116  of each TFT  108  may be electrically connected to a gate line  104 . A drain  118  of each TFT  108  may be electrically connected to a respective pixel electrode  110 . Each TFT  108  may serve as a switching element that may be activated and deactivated (e.g., turned “ON” and turned “OFF”) for a predetermined period of time based on the respective presence or absence of a scanning signal on the gate lines  104  that are applied to the gates  116  of the TFTs  108 . 
     When activated, a TFT  108  may store the image signals received via the respective data lines  106  as a charge upon its corresponding pixel electrode  110 . As noted above, the image signals stored by the pixel electrode  110  may be used to generate an electrical field between the respective pixel electrode  110  and a common electrode  112 . This electrical field may align the liquid crystal molecules to modulate light transmission through the pixel  102 . Furthermore, although not illustrated, it should be appreciated that each unit pixel  102  may also include a storage capacitor C ST  that may used to sustain the pixel electrode voltage (e.g., V pixel ) during the time in which the TFTs  108  may be switch to the “OFF” state. 
     The display  18  may also include source driver integrated circuits (IC)  120 . The source driver IC  120  may include a chip, such as a processor or application specific integrated circuit (ASIC) that controls the display pixel array  100  by receiving image data  122  (e.g., split images) from the processor(s)  12 , and sending the corresponding split image signals to the unit pixels  102  of the pixel array  100 . The source driver  120  may also provide timing signals  126  to, for example, a gate driver  124  to facilitate the activation/deactivation of individual rows of pixels  102 . In other embodiments, timing information may be provided to the gate driver  124  in some other manner. The display  18  may or may not include a common voltage (VCOM) source  128  to provide a common voltage (VCOM) voltage to the common electrodes  112 . In certain embodiments, the VCOM source  128  may supply a different VCOM to different common electrodes  112  at different times. In other embodiments, the common electrodes  112  all may be maintained at the same potential or similar potential. 
     In certain embodiments, as further illustrated in  FIG. 6 , the processor(s)  12  may include one or more graphics processing units (GPUs)  130  that may be used to generate and render images to the display  18 . In one embodiment, the one or more GPUs  130  may be communicatively coupled to an internal memory  132 . In certain embodiments, the internal memory  132  may store one or more adaptive dimming components  134  (e.g., adaptive dimming algorithm(s) and/or hardware components used to implement the adaptive dimming) for providing the image data  122  to the pixel array  100  of the display  18 . 
     The adaptive dimming component  134  (e.g., adaptive dimming algorithm(s)  134  and/or hardware components used to implement the adaptive dimming) may include any code or instructions that, when executed by the GPUs  130  and/or the processor(s)  12  at large, may be useful in calculating, splitting, and processing image data to be displayed on the display  18 . It should be appreciated that while the adaptive dimming component  134  may be illustrated as being executed by the GPUs  130 , in other embodiments, the adaptive dimming component  134  (e.g., adaptive dimming algorithm(s)  134  and/or hardware components used to implement the adaptive dimming) may be executed by the source driver  120 , or by other data processing circuitry that may be included as part of the processor(s)  12 . 
     For example,  FIG. 7  illustrates a process  136 , which may be illustrative of the operation of the adaptive dimming component  134  as discussed above with respect to  FIG. 6 . The process  136  may include code or instructions stored in a non-transitory machine-readable medium (e.g., the memory  14  or the internal memory  132 ) and executed, for example, by the one or more processor(s)  12 , the GPUs  130 , and/or the source drivers  120  included within the system  10  and illustrated in  FIG. 6 . The process  136  may begin with the GPUs  130  receiving (block  138 ) one or more frames of image data. The process  136  may continue with the GPUs  130  increasing (block  140 ) the brightness values of some of the pixels while preserving local contrast. For example, as will be described in greater detail below, the present adaptive dimming techniques may include defining global thresholds (e.g., global backlight thresholds BL 1 , BL 2 , and BL 3 ) based on a global histogram, and then locally adjusting the global backlight levels BL 1  and BL 2  into local thresholds (e.g., local backlight thresholds) based on the global values and a local histogram and local tone mapping function. 
     The process  136  may then continue with the GPUs  130  adjusting (block  142 ) the intensity of the backlight of the display  18 . For example, as will be discussed in greater detail below, by allowing minor distortion in the form of lost pixel contrast to be introduced to some pixels (e.g., as discussed with respect to block  140 ), the backlight intensity may be more aggressively reduced at (e.g., as discussed with respect to block  142 ). The process  136  may thus result in the GPUs  130  causing (block  144 ) the display  18  to display the resulting image with such relatively minimal distortion, while offering substantially improved power savings. In this way, the present adaptive dimming techniques with local tone mapping may reduce possible image errors (e.g., clipping errors, halo artifacts, and so forth) and power consumption while providing a high contrast ratio. 
       FIG. 8  illustrates a simplified example of the present adaptive dimming techniques. Specifically,  FIG. 8  illustrates an original image  146  and an image  148  in which the present adaptive dimming techniques with local tone mapping have been applied. As illustrated by the image  148 , the present adaptive dimming techniques with local tone mapping may preserve local contrast (e.g., as illustrated by the icon strip  149  in the image  148 ) instead of clipping and distorting pixel  102  values. Specifically, in one embodiment, the image  148  may include a preservation matrix in which only pixels  102  above the lower limit of the local contrast adjustment (e.g., BL 3 ) are corrected while neighboring pixels  102  remain unadjusted. That is, the present adaptive dimming techniques with local tone mapping may allow only the pixels  102  (e.g., which may correspond to a single segment of the light sources of the display  18 ) corresponding to the icon strip  149  in the image  148  to be adjusted in order to preserve the local contrast and to reduce the possibility of any image errors (e.g., clipping errors, halo artifacts, and so forth). 
       FIG. 9  illustrates one or more computational blocks that may be included as part of the adaptive dimming component  134  (e.g., adaptive dimming algorithm(s)  134  and/or hardware components used to implement the adaptive dimming). Indeed, the computational blocks  150 ,  152 ,  154 ,  156 , and  158  may include hardware, software, or some combination of hardware and software. As depicted, pixel data (e.g., image data  122 ) may be provided to a global histogram block  150 , as well as a local histogram block  156  and local pixel adjustment block  158 . Specifically, a global histogram may be generated by the GPUs  130  based on the pixel data (e.g., image data  122 ). As further depicted, global thresholds (e.g., global backlight thresholds BL 1 , BL 2 , and BL 3 ) may be generated via the global histogram block  150 . Particularly, based on the generated global histogram, the three thresholds (e.g., global backlight thresholds BL 1 , BL 2 , and BL 3 ) may be defined, in which BL 1  may be defined as the upper limit of the local dynamic range and BL 2  may be defined as the lower limit of the local dynamic range via the local histogram definition block  156 . Similarly, BL 3  may be defined as the lower limit of the local contrast adjustment (e.g., global threshold) such that brightness levels below BL 3  (e.g., outside the local adjustment area or outside of the local dynamic range) may not be adjusted. 
     For example, in one embodiment, the local dynamic range may be expressed as:
 
 BL   2 ≦Local Dynamic Range≦ BL   1  
 
     As further depicted in  FIG. 9 , a local histogram may be generated via a local histogram block  154  based on the incoming pixel data (e.g., image data  122 ). In some embodiments, and as will be further appreciated with respect to  FIG. 10 , the local histogram may be representative of a single segment of pixels  102  and/or light sources (e.g., 1-dimensional (1-D) dimming) of the display  18 , or multiple segments of pixels  102  and/or light sources (e.g., 2-D dimming). The local histogram definition block  156  may also define a target light source (e.g., backlight) brightness level for the local pixels  102 . Thus, based on the local backlight levels BL 1  and BL 2  and the global backlight level BL 3 , the pixel values of the incoming pixel data (e.g., image data  122 ) may be adjusted utilizing a local tone mapping function. In this way, the present adaptive dimming techniques with local tone mapping may reduce possible image errors (e.g., clipping errors, halo artifacts, and so forth) and power consumption while providing a high contrast ratio. 
       FIG. 10  illustrates an image  160 , which may be a still image or a video image displayed on the display  18 . As an example, the image  160  may include images of a first object  162  (e.g., a wall mounted picture) and a second object  164  (e.g., a lamp). As may be appreciated, the first object  162  and the second object  164  may each include dark to bright pixels (e.g., pixel values). As illustrated, a local dynamic range  166  may be defined in the image  160 . Specifically, as will be further appreciated with respect to  FIG. 11 , the image  160 , and more specifically, the local dynamic range  166 , may illustrate the aforementioned three thresholds BL 1 , BL 2 , and BL 3 . For example, employing the present adaptive dimming techniques with local tone mapping may preserve the details and contrast of the image  160  (e.g., the second object  164  (lamp) may include brighter pixel content than that of the first object  162  (wall mounted picture)) without producing image errors (e.g., clipping errors, halo artifacts, and so forth). 
       FIG. 11  illustrates an example of a pixel map  168  or a local histogram of a 1-D or 2-D vertical segment of pixels  102  of the display  18  as plot of luminance (e.g., brightness) versus the number of pixels  102  within the local segment of pixels  102 . Indeed, the pixel map  168  is an illustration of the operation of the three thresholds BL 1 , BL 2 , and BL 3 , and the visual comparison of the present adaptive dimming techniques with local tone mapping and the previously discussed the DPB adaptive dimming technique as applied to horizontal segments of pixels  102 . In one embodiment, the pixel map  168  may be representative of the local dynamic range  166  (e.g., a single segment of pixels  102  and a corresponding segment of light sources) as discussed above with respect to  FIG. 10 . As depicted by the pixel map  168  and previously noted above with respect to  FIG. 9 , the threshold  170  (e.g., BL 3 ) may be a global backlight level, and more specifically, the lower limit of the local contrast adjustment such that the luminance (e.g., brightness) of the pixels  102  below threshold BL 3  may not be adjusted. 
     However, on the other hand, the upper limit of the local dynamic range  172  (e.g., BL 1 ) (illustrated above the physical backlight  174  (e.g., “Physical BL”)) and the lower limit of the local dynamic range  176  (e.g., BL 2 ) (illustrated below the physical backlight  174  (e.g., “Physical BL”)) may each be locally adjusted to preserve the local contrast and luminance (e.g., brightness) of, for example, the segment of pixels  102  within defined by the local dynamic range  166  in the image  160  of  FIG. 10 . Specifically, as further depicted by the pixel map  168 , the plot  182  (e.g., “Adaptive Dimming with Local Tone Mapping”) illustrates that the luminance (e.g., brightness) and color preservation is markedly improved as compared to the original plot  178  (e.g., “Original”) and the plot  180  (e.g., “DPB”). For example, the luminance (e.g., brightness), color, and/or other image or pixel content of the second object  164  (e.g., the lamp in the image  160  of FIG.  10 ) may be preserved while, for example, the image or pixel content of the first object  162  (e.g., wall mounted picture in the image  160  of  FIG. 10 ) may be unadjusted. 
       FIG. 12  illustrates an example of a pixel map  184  or a local histogram of a 1-D or 2-D horizontal segment of pixels  102  of the display  18  as plot of number of pixels  102  within the local segment of pixels  102  versus gray level intensity. Indeed, the pixel map  168  is an illustration of the operation of the three thresholds BL 1 , BL 2 , and BL 3 , and another visual illustration of the present adaptive dimming techniques with local tone mapping applied to vertical segments of pixels  102  (e.g., “Untouched Region,” “Affected Region,” and “Triggering Region”). As depicted by the pixel map  184  and previously noted above with respect to  FIGS. 9 and 11 , the threshold  186  (e.g., BL 3 ) may be the lower limit of the local contrast adjustment such that the luminance (e.g., brightness) of the pixels  102  below threshold BL 3  may not be adjusted (e.g., “Untouched Region”). 
     Similarly, as discussed above with respect to  FIG. 11 , the upper limit of the local dynamic range  188  (e.g., BL 1 ) (beyond which is referred to as the “Triggering Region”) and the lower limit of the local dynamic range  190  (e.g., BL 2 ) (between which is referred to as the “Affected Region”) may each be locally adjusted to preserve the local contrast and luminance (e.g., brightness) of, for example, the segment of pixels  102  within defined by the local dynamic range  166  in the image  160  of  FIG. 10 . Furthermore, the pixel map  184  illustrates that only the pixels  102  in the “Affected Region” (e.g., pixels  102  to the left of the lower limit of the local contrast BL 3 ) may be adjusted while, in some embodiments, the majority of the pixels  102  may be unadjusted (e.g., pixels  102  in the “Untouched Region”). 
       FIGS. 13A-13G  display examples of the present adaptive dimming techniques with local tone mapping. For example,  FIG. 13A  depicts an original image  192 , which includes an image  194  (e.g., an image of a triangle). In some embodiments, the original image  192  may be a still image (e.g., photo), or in other embodiments, the original image  192  may be a video image. Specifically, as will be appreciated from  FIGS. 13A-13G , the present adaptive dimming techniques with local tone mapping may include utilizing and/or applying a preservation matrix (e.g., via the GPU(s)  130  executing the adaptive dimming component  134  as discussed above with to  FIG. 6 ), which may include applying image correction for darker pixels and applying minimal image correction for brighter pixels. For example, as generally illustrated by the images  196 ,  198 ,  200 ,  202 ,  204 , and  206  of  FIGS. 13B-13G , a sequence of locally corrected pixels (e.g., pixels  102  above the lower limit of the local contrast BL 3 ) may be adjusted while the neighboring pixels  102  (e.g., pixels  102  below the lower limit of the local contrast BL 3 ) may remain unadjusted. The preservation matrix  208  of  FIG. 13G  depicts the pixels  102  of the original image that has been adjusted to preserve the expected luminance (e.g., brightness) of these pixels. 
     In certain embodiments, the adaptive dimming component  134  may include instructions to determine the luminance (e.g., brightness) preservation value and/or matrix based on, for example, the subpixel of the three subpixels of each pixel  102  with the maximum luminance (e.g., brightness). Thus, the adaptive dimming component  134  may perform a local histogram analysis to determine the expected brightness level for each local segment of pixels  102  (e.g., corresponding to a segment of light sources of the display  18 ). For example, the luminance levels (e.g., RGB color levels) of the local pixels  102  may experience a variation in gain (e.g., adaptive boosting) to preserve the expected luminance (e.g., brightness) while the neighboring pixels  102  may be adaptively dimmed or unadjusted to increase the contrast ratio of the image without causing image errors (e.g., clipping errors, halo artifacts, and so forth). 
       FIG. 14  illustrates another detailed embodiment of the adaptive dimming component  134  (e.g., adaptive dimming algorithm(s)  134  and/or hardware components used to implement the adaptive dimming) of  FIG. 6 . In certain embodiments, as generally discussed above with respect to  FIG. 9 , the adaptive dimming component  134  may include a global computational component  210  and local computational component  212 , which may each generate and supply pixel luminance analysis signals to a pixel manipulation component  214  (e.g., luminance and color preservation matrix). In certain embodiments, as further depicted in  FIG. 14 , the global computational component  210  may include global histogram block  216 , which may generate a set of global thresholds (e.g., global backlight thresholds BL 1 , BL 2 , and BL 3 ). 
     In certain embodiments, the global computational component  210  may supply the global thresholds (e.g., BL 1 , BL 2 , and BL 3 ) to a risk analysis and backlight update block  218  of the local computational component  212 . In some embodiments, the risk analysis and backlight update block  218  may be used to analyze and calculate a risk value based on, for example, the global thresholds (e.g., BL 1 , BL 2 , and BL 3 ) and the localized backlight levels BL 1  and BL 2 . For example, in one embodiment, the risk analysis and backlight update block  218  may compute a risk value and/or apply a risk function that may be useful in determining, for example, the proper balance between dimming dark pixels and preserving the intended luminance (e.g., brightness) of bright pixels for one or more local segments of an image. 
     As further depicted, in certain embodiments, the risk analysis and backlight update block  218  of the local computational component  212  may supply a first input (e.g., filter settings) to a first filter  220  (e.g., moving average (MA) filter) of the global computational component  210  based on the global threshold BL 1 . The risk analysis and backlight update block  218  may also supply a second input to a second filter  222  (e.g., MA filter) of the global computational component  210  based on the global thresholds BL 2  and BL 3 . The risk analysis and backlight update block  218  may also supply a third input to the global histogram block  216  as a feedback signal indicating higher risk images (e.g., higher risk for pixel distortion and clipping errors) to be utilized by the global histogram block  216  as part of the calculation of the target backlight level. 
     In some embodiments, as further depicted, the risk analysis and backlight update block  218  may also receive local cell values from a local histogram block  226  (maximum cell relevance output from a cell histogram block  228 ), and determine a scene change ratio (e.g., strength and direction) based, for example, on a temporally filtered backlight level, the target backlight level, a previous target backlight level, and the scene change ratio. Based on these data, the risk analysis and backlight update block  218  may determine temporal filter setting to be supplied to the first filter  220  and a filter  236  (e.g., infinite impulse response (IIR) filter) to be utilized in the computation of the local backlight levels BL 1  and BL 2 . 
     In some embodiments, the first filter  220  and the second filter  222  may calculate one or more sets of averages of the pixel content corresponding to the global threshold BL 1  and BL 3 , respectively. The first filter  220  (e.g., MA filter) may also supply a signal indicative of a temporal component of the global threshold BL 1  to a pulse width modulation (PWM) block  224  and the local histogram block  226  of the local computational component  212  based on the luminance (e.g., brightness) of each RGB subpixel of, for example, pixels  102  of the segment of pixels  102 . The second filter  222  (e.g., MA filter) may supply a corresponding signal indicative of the temporal component of the global thresholds BL 2  and BL 3  to a cell histogram block  228  based on the luminance (e.g., brightness) of each RGB subpixel of, for example, pixels  102  of the segment of pixels  102 . 
     In certain embodiments, the outputs of the cell histogram block  228  and a cell relevance block  230  may be multiplied via a multiplier  232  to generate local threshold BL 1 . The local threshold BL 1  may be then supplied to a spatial filter  234 . The cell histogram block  228  may also generate local threshold BL 2  and supply the local threshold BL 2  to the spatial filter  234 . In one embodiment, the local threshold BL 1  and the local threshold BL 2  may each include a different size or different magnitude or value. Indeed, in some embodiments, the local cell value for the local threshold BL 2  may be an average value of the histogram entries between the physical backlight level and 0 (e.g., relevant entries). For example, if the number of relevant histogram entries is deemed too low (e.g., lower than the global threshold BL 3 ), the global threshold BL 3  may be used as the lower bound (e.g., lower limit). 
     As further depicted in  FIG. 14 , the local threshold BL 1  and the local threshold BL 2  may be supplied to the filter  236  (e.g., infinite impulse response (IIR) filter), and these outputs may be provided to an interpolation block  238 . The interpolation block  238  may then calculate local thresholds BL 1  and BL 2 , and supply the local thresholds BL 1  and BL 2  (e.g., local backlight thresholds for each pixel or segment of pixels) to the pixel manipulation component  214  (e.g., luminance and color preservation matrix). In one embodiment, each local filter  236  may be then adaptive, in which the filter  236  length may be updated and/or adjusted on a frame by frame basis based on an input (e.g., filter settings input) provided the risk analysis and backlight update block  218 . Thus, based on the local backlight levels BL 1  and BL 2  and the global backlight level BL 3 , pixel manipulation component  214  (e.g., luminance and color preservation matrix) may used be used to adjust the pixel values of the incoming pixel data (e.g., image data  122 ) utilizing a local tone mapping function. In this way, the present adaptive dimming techniques with local tone mapping may reduce possible image errors (e.g., clipping errors, halo artifacts, and so forth) and power consumption while providing a high contrast ratio. 
       FIG. 15  illustrates an alternative embodiment to that described with respect  FIG. 14 . Specifically, as depicted in  FIG. 15 , the calculations for the local thresholds BL 1  and BL 2  may not be performed in parallel (e.g., as discussed with respect to  FIG. 14 ). For example, as depicted, the second filter  222  (e.g., MA filter) may supply a signal indicative of the temporal component of the global thresholds BL 2  and BL 3  to the cell histogram block  228  based on the luminance (e.g., brightness) of each RGB subpixel of, for example, pixels  102  of the segment of pixels  102 . The second filter  222  (e.g., MA filter) may supply signals indicative of the temporal component of the global thresholds BL 2  and BL 3  to the cell histogram block  228  based on the luminance (e.g., brightness) of each RGB subpixel, and thus the initial local cell values for the local threshold BL 2  may not be determined based on the local histogram block  226  (e.g., as illustrated for the local threshold BL 1 ). The second filter  222  (e.g., MA filter) may also supply a signal indicative of the temporal component of the global thresholds BL 2  and BL 3  to the pixel manipulation component  214  (e g, luminance and color preservation matrix), as oppose to only the global threshold BL 1  as discussed above with respect to  FIG. 14 . 
       FIG. 16  illustrates another embodiment of the adaptive dimming component  134  (e.g., adaptive dimming algorithm(s)  134  and/or hardware components used to implement the adaptive dimming) of  FIG. 6 . Specifically, in one embodiment,  FIG. 15  depicts an embodiment of the adaptive dimming component  134  (e.g., as previously discussed with respect to  FIG. 14 ) with a frame by frame temporal integration, in which the luminance (e.g., brightness) of one or more pixels of each frame of pixels of the display  18  may be adjusted. For example, in certain embodiments, the adaptive dimming component  134  may be used to generate a number of pixel luminance (e.g., brightness) levels and histograms  216 A,  216 B,  216 C, and  216 D for each localized segment of pixels and/or corresponding light sources (e.g., backlights) of the display  18  and for each new frame of image data  240  (e.g., “Frame f- 3 ”),  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f”). 
     In one embodiment, the pixel luminance of the image data may be spatiotemporally filtered. In another embodiment, the adaptive dimming component  134  may analyze the histograms  216 A,  216 B,  216 C, and  216 D without temporal filtering. As further depicted, the risk analysis and backlight update blocks  218 A,  218 B,  218 C, and  218 D of the respective frames of image data  240  (e.g., “Frame f- 3 ”),  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f) may compute a risk value and/or apply a risk function based on, for example, the respective histogram  216 A,  216 B,  216 C, and  216 D analysis data and local risk values generated from the previous frame of image data. 
     Similarly, the respective local threshold filters  236 A,  236 B,  236 C, and  236 D may generate the local backlight levels BL 1  and BL 2  for each of the respective frames of image data  240  (e.g., “Frame f- 3 ”),  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f) based on the respective global thresholds (e.g., BL 1 , BL 2 , and BL 3 ) and the local backlight levels BL 1  and BL 2  from the respective previous frames of image data  240  (e.g., “Frame f- 3 ”),  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f). Lastly, the pixels of a given frame  240  (e.g., “Frame f- 3 ”),  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f) may be adjusted based on, for example, respective local cell values of the previous frame  240  (e.g., “Frame f- 3 ”),  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f) and the respective current luminance level for the immediate frame  240  (e.g., “Frame f- 3 ”),  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f). 
       FIG. 17  depicts an embodiment of the adaptive dimming component  134  with the frame by frame temporal integration as discussed with respect to  FIG. 16 , but illustrating that risk values are calculated by the respective risk analysis and backlight update blocks  218 B,  218 C, and  218 D between each new frame of image data  242  (e.g., “Frame f- 2 ”),  244  (e.g., “Frame f- 1 ”), and  246  (e.g., “Frame f”) during the respective vertical blanking periods  248  and  250  as illustrated. In this way, as previously discussed above with respect to  FIG. 14 , each local filter  236 B,  236 C, and  236 D may be then adaptive, and thus allowing the length of each local filter  236 B,  236 C, and  236 D to be updated and/or adjusted on a frame by frame basis based on real-time updated inputs (e.g., filter settings input) provided the respective risk analysis and backlight update blocks  218 B,  218 C, and  218 D. 
     Turning now to  FIG. 18 , a flow diagram is presented, illustrating an embodiment of a process  250  useful in reducing image errors (e.g., clipping errors, halo artifacts, and so forth) and power consumption while providing a high contrast ratio by using, for example, the one or more the processor(s)  12  and/or GPU(s)  130  depicted in  FIGS. 1 and 6 . The process  250  may include code or instructions stored in a non-transitory machine-readable medium (e.g., the memory  14 ) and executed, for example, by the one or more processor(s)  12  and/or GPU(s)  130 . The process  250  may begin with the GPU(s)  130  receiving (block  252 ) image data (e.g., image data  122 ). The process  250  may continue with the GPU(s)  130  performing (block  254 ) a global histogram analysis of the image data. The process  250  may then continue with the GPU(s)  130  generating (block  256 ) a set of thresholds based on the global histogram analysis. For example, the GPU(s)  130  may generate global thresholds BL 1 , BL 2 , and BL 3 . 
     The process  250  may then continue with the GPU(s)  130  defining (block  258 ) a first threshold and a second threshold as local thresholds based on the global histogram analysis and a local histogram analysis utilizing a local tone mapping function. Specifically, as previously noted above with respect to  FIGS. 9-11 , based on the generated global histogram, the local thresholds BL 1  and BL 2  may be defined, in which BL 1  may be defined as the upper limit of the local dynamic range and BL 2  may be defined as the lower limit of the local dynamic range. The process  250  may then conclude with the GPU(s)  130  adjusting (block  260 ) the first and second thresholds to adjust a brightness adjust a luminance of one or more pixels of image data. For example, based on the local backlight levels BL 1  and BL 2  and the global backlight level BL 3 , pixel manipulation component  214  (e g, luminance and color preservation matrix) may used be used to adjust the pixel values of the incoming pixel data (e.g., image data  122 ) utilizing a local tone mapping function. In this way, the present adaptive dimming techniques with local tone mapping may reduce possible image errors (e.g., clipping errors, halo artifacts, and so forth) and power consumption while providing a high contrast ratio. 
     As another example,  FIG. 19  illustrates simulation examples of an original image  262 , and an image  264  generated without using the presently disclosed adaptive dimming with local tone mapping techniques including, for example, image artifacts (e.g., clipping errors, halo artifacts, and so forth) as compared to a similar image  266  generated using the presently disclosed adaptive dimming with local tone mapping techniques. For example, the image  264  generated without using the presently disclosed techniques includes flashing artifacts (e.g., halos) or washed-out pixels (e.g. clipping errors) (e.g., as may be viewed via the magnified portions  268  and  270  of the image  264 ). In contrast, the image  266  generated according to the presently disclosed techniques includes reduced and eliminated clipping artifact and improved contrast (e.g., as may be viewed via the magnified portions  272  and  274  of the image  266 ). 
     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: 20150804
Publication Date: 20170822
Grant Date: 20170822
Priority Date: 20150804
Inventors: JUNG TOBIAS
ALBRECHT MARC
PINTZ SANDRO H.
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2360/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0646", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3426", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06T5/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0646", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0646", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3426", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3426", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06T5/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06T5/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06T5/90", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06T5/90", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 58053510