PATENT DOCUMENT

Publication Number: US-10504452-B2
Application Number: US-201815918879-A
Country: US
Kind Code: B2

Title: Pixel contrast control systems and methods

Abstract:
An electronic device may include a display pipeline to be coupled between an image data source and a display panel. The display pipeline may include pixel contrast control processing circuitry programmed to determine pixel statistics indicative of an image frame based at least in part on image data that indicates an initial target luminance of a corresponding display pixel implemented on the display panel. The pixel contrast control circuitry may also apply a set of local tone maps to determine modified image data that indicates a modified target luminance. The display pipeline may also include a pixel contrast control controller coupled to the pixel contrast control processing circuitry. The pixel contrast control controller may be programmed to execute firmware instructions to determine local tone maps to be applied during the next image frame based at least in part on the pixels statistics determined by the pixel contrast control processing circuitry.

Claims:
What is claimed is: 
     
       1. An electronic device comprising a display pipeline configured to be coupled between an image data source and a display panel, wherein the display pipeline comprises:
 pixel contrast control processing circuitry comprising circuit connections programmed to: 
 determine first pixel statistics indicative of content of a current image frame based at least in part on received image data that indicates an initial target luminance of a corresponding display pixel implemented on the display panel during the current image frame, wherein determining the first pixel statistics comprises:
 determining an active region in the current image frame, wherein the active region comprises a first set of local windows; 
 determining a plurality of luma values, each associated with one image pixel in the current image frame; 
 determining a first global luma histogram based at least in part on luma values associated with each image pixel in the active region; and 
 determining a plurality of local luma histograms each associated with a corresponding local window of the first set of local windows based at least in part on luma values associated with each image pixel in the corresponding local window; and 
 
 apply a first plurality of local tone maps determined based at least in part on second pixel statistics associated with a previous image frame to determine modified image data that indicates a modified target luminance of the corresponding display pixel during the current image frame; and 
 a pixel contrast control controller coupled to the pixel contrast control processing circuitry, wherein the pixel contrast control controller is programmed to execute firmware instructions to determine a second plurality of local tone maps to be applied during a next image frame based at least in part on the first pixel statistics received from the pixel contrast control processing circuitry. 
 
     
     
       2. The electronic device of  claim 1 , wherein
 the active region excludes portions of the current image frame which comprise subtitles, a picture-in-picture area, a constant color, or a combination thereof. 
 
     
     
       3. The electronic device of  claim 2 , wherein, to determine the second plurality of local tone maps, the pixel contrast control controller is programmed to:
 determine a second global luma histogram associated with the previous image frame; and 
 determine each of the second plurality of local tone maps based at least in part on the second global luma histogram and a corresponding local luma histogram of the plurality of local luma histograms associated with the current image frame. 
 
     
     
       4. The electronic device of  claim 2 , wherein, to determine the first pixel statistics, the pixel contrast control processing circuitry is programmed to:
 determine a second set of local windows completely enclosed within the active region of the current image frame;
 determine a plurality of maximum color component values each associated with one image pixel in the current image frame based at least in part on the received image data; 
 determine a first global maximum color component histogram based at least in part maximum color component value associated with each image pixel in the active region; and 
 determine a first plurality of largest maximum color component values and a first plurality of average maximum color component values each associated with a second corresponding local window of the second set of local windows based at least in part on maximum color component value associated with each image pixel in the second corresponding local window. 
 
 
     
     
       5. The electronic device of  claim 4 , wherein the pixel contrast control processing circuitry is programmed to determine whether a scene change occurred between the previous image frame and the current image frame based at least in part on:
 comparison between the first global maximum color component histogram associated with the current image frame and a second global maximum color component histogram associated with the previous image frame; 
 comparison between the first plurality of largest maximum color component values associated with the current image frame and a second plurality of largest maximum color component values associated with the previous image frame; 
 comparison between the first plurality of average maximum color component values associated with the current image frame and a second plurality of average maximum color component values associated with the previous image frame; or 
 
       any combination thereof. 
     
     
       6. The electronic device of  claim 1 , wherein, to apply the first plurality of local tone maps, the pixel contrast control processing circuitry is programmed to:
 apply a first local tone map to the received image data when the pixel contrast control processing circuitry determines that a scene change occurred directly before the previous image frame; and
 apply a temporally filtered tone map determined by temporally filtering the first local tone map with a second local tone map applied in the previous image frame to the received image data when the pixel contrast control processing circuitry does not determine that a scene change occurred directly before the previous image frame. 
 
 
     
     
       7. The electronic device of  claim 1 , wherein, to apply the first plurality of local tone maps, the pixel contrast control controller is programmed to:
 determine a first pixel position associated with the received image data; 
 determine a first local tone map of the first plurality of local tone maps associated with a second pixel position; 
 apply the first local tone map to the received image data determine a first result; 
 determine a second local tone map of the first plurality of local tone maps associated with a third pixel position; 
 apply the second local tone map to the received image data to determine a second result; and 
 determine the modified image data based at least in part on interpolation of the first result and the second result based at least in part on a first distance between the first pixel position and the second pixel position and a second distance between the first pixel position and the third pixel position. 
 
     
     
       8. The electronic device of  claim 7 , wherein, to apply the first plurality of local tone maps, the pixel contrast control controller is programmed to:
 determine a third local tone map of the first plurality of local tone maps associated with a third pixel position;
 apply the third local tone map to the received image data determine a third result; 
 
 determine a fourth local tone map of the first plurality of local tone maps associated with a fourth pixel position;
 apply the fourth local tone map to the received image data to determine a fourth result; and 
 determine the modified image data by: 
 interpolating the first result and the second result based at least in part on a first distance between the first pixel position and the second pixel position and a second distance between the first pixel position and the third pixel position to determine a first intermediate result; 
 interpolating the third result and the fourth result based at least in part on a third distance between the first pixel position and the third pixel position and a fourth distance between the first pixel position and the fourth pixel position to determine a second intermediate result; and 
 interpolating the first intermediate result and the second intermediate result. 
 
 
     
     
       9. The electronic device of  claim 1 , wherein the electronic device comprises a portable phone, a media player, a personal data organizer, a handheld game platform, a tablet device, a computer, or any combination thereof. 
     
     
       10. A method for processing image data to adjust perceived contrast, a light output level, or a combination thereof of an electronic display comprising:
 receiving, via a pixel contrast control block of an electronic device, the image data; 
 determining, via the pixel contrast control block, pixel statistics from the image data, wherein the pixel statistics comprise a luma level for at least one pixel, wherein the luma level for the at least one pixel is selected from one of an average luma level, a maximum luma level, and a mixed luma level based at least in part on a value of a target brightness relative to a first brightness threshold and a second brightness threshold, wherein the mixed luma level comprises a combination of the maximum luma level and the average luma level for the at least one pixel; 
 determining, via the pixel contrast control block, one or more tone maps, at least in part, from the pixel statistics; 
 applying the one or more tone maps to the image data; and 
 outputting, via the pixel contrast control block, the image data with the one or more tone maps applied to an electronic display. 
 
     
     
       11. The method of  claim 10 , comprising determining, via the pixel contrast control block, a dimming factor, wherein the dimming factor is configured to set the light output level of a light source of the electronic display. 
     
     
       12. The method of  claim 11 , wherein the dimming factor is temporally filtered to smooth changes in the light output level. 
     
     
       13. The method of  claim 10 , wherein the one or more tone maps are determined, at least in part, on environmental factors, wherein the environmental factors comprise an ambient lighting condition. 
     
     
       14. The method of  claim 10 , wherein at least a portion of the pixel statistics is processed through a low-pass filter to smooth spatial outliers of the image data. 
     
     
       15. A method for processing image data to increase perceived contrast on an electronic display comprising:
 determining, via a pixel contrast control block of an electronic device, pixel statistics from the image data; 
 determining, via the pixel contrast control block, a first set of tone maps based, at least in part, on the pixel statistics, wherein the first set of tone maps is temporally filtered; 
 determining, via the pixel contrast control block, a second set of tone maps based, at least in part, on the pixel statistics, wherein the second set of tone maps is not temporally filtered; and 
 applying, via the pixel contrast control block, either the first set of tone maps or the second set of tone maps to the image data. 
 
     
     
       16. The method of  claim 15 , comprising, in response to determining a scene change from the pixel statistics, applying the second set of tone maps. 
     
     
       17. The method of  claim 15 , wherein determining the pixel statistics comprises converting the image data to a non-linear gamma space. 
     
     
       18. The method of  claim 15 , wherein the first set of tone maps or the second set of tone maps are applied to the image data over a frame grid. 
     
     
       19. The method of  claim 18 , wherein an interpolation of the first set of tone maps or the second set of tone maps is applied to each of a plurality of pixels based at least in part on a location of each of the plurality of pixels. 
     
     
       20. The method of  claim 10 , wherein:
 the second brightness threshold is greater than the first brightness threshold; 
 the selected luma level comprises the average luma level in response to the value of the target brightness being less than the first brightness threshold; 
 the selected luma level comprises the mixed luma level in response to the value of the target brightness being between the first brightness threshold and the second brightness threshold; and 
 the selected luma level comprises the maximum luma level in response to the value of the target brightness being greater than the second brightness threshold.

Description:
BACKGROUND 
     The present disclosure relates generally to electronic displays and, more specifically, to processing image data to be used to display images on an electronic display. 
     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 often use one or more electronic displays to present visual representations of information as text, still images, and/or video by displaying one or more images (e.g., image frames). For example, such electronic devices may include computers, mobile phones, portable media devices, tablets, televisions, virtual-reality headsets, and vehicle dashboards, among many others. To display an image, an electronic display may control light emission (e.g., luminance) of its display pixels based at least in part on corresponding image data. Generally, luminance of display pixels while displaying an image may affect perceived brightness and, thus, perceived contrast (e.g., brightness difference between display pixels) in the image. In fact, at least in some instances, increasing contrast may facilitate improving image sharpness and, thus, perceived image quality. 
     However, environmental factors, such as ambient lighting conditions, may affect perceived contrast. For example, ambient light incident on the screen of an electronic display may increase perceived brightness of dark display pixels relative to perceived brightness of bright pixels. As such, increasing ambient light may reduce perceived contrast in an image, which, at least in some instances, may result in the image appearing washed out. 
     To facilitate improving perceived contrast, in some instances, luminance of bright display pixels may be further increased relative to luminance of dark display pixels, for example, to counteract ambient lighting conditions. However, luminance increases in an electronic display may nevertheless be limited by maximum brightness of its light source (e.g., LED backlight or OLED display pixels). Moreover, increasing luminance of its display pixels may increase power consumption resulting from operation of an electronic display. 
     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. 
     Accordingly, to facilitate improving perceived image quality and/or reducing power consumption, the present disclosure provides techniques for implementing and operating a pixel contrast control (PCC) block in a display pipeline, for example, coupled between an image data source and a display panel of an electronic display. In some embodiments, the pixel contrast control block may include processing circuitry (e.g., hardware) that modifies image data to adjust resulting color hue and/or luminance in a manner expected to facilitate improving perceived contrast. For example, to modify an image pixel, the pixel contrast control processing circuitry may determine pixel position of the image pixel and apply, to the image pixel, one or more local tone maps each associated with a corresponding pixel position. When multiple (e.g., four nearest) local tone maps are applied, in some embodiments, the pixel contrast control processing circuitry may interpolate the results based at least in part on distance between the pixel position of the image pixel and the pixel positions associated with the local tone maps. 
     Additionally, to facilitate improving perceived contrast, in some instances, the luminance of bright display pixels may be increased or altered relative to luminance of dark display pixels, for example, to counteract ambient lighting conditions. For example, an electronic display may increase luminance of its display pixels by increasing electrical power supplied to a light source, such a backlight implemented adjacent the display pixels and/or organic light-emitting diodes (OLEDs) implemented in the display pixels. 
     In some embodiments, the pixel contrast control processing circuitry may determine pixel statistics, which may be indicative of the pixel luminance and color hues of the image. The pixel statistics may, thus, be used to determine the local tone maps. In some embodiments, the pixel statistics may be gathered based on local windows (e.g., cells) defined in a current image frame. Additionally, the pixel contrast control processing circuitry may determine global pixel statistics based on an active region defined in the current image frame. The active region may exclude static portions of a current image frame, such as subtitles. In some embodiments, the pixel statistics may include the maximum color component values, average values, histograms, and/or luma values of each image pixel in the active region. 
     In some embodiments, the luma value associated with an image pixel may be determined based at least in part on a target brightness level. For example, the luma value corresponding with an image pixel may be set as an average luma value (e.g., weighted average of color components), a maximum luma value (e.g., maximum of weighted color components), and/or a mixed luma value. In some embodiments, the mixed luma value may be determined by mixing the average luma value and the maximum luma value, for example, to produce a smooth transition therebetween. 
     The pixel contrast control block may additionally include a controller (e.g., processor) that executes instructions (e.g., firmware) to determine one or more local tone maps based at least in part on detected environmental conditions and the pixel statistics received from the pixel contrast control processing circuitry. In some embodiments, the pixel statistics and the local tone maps may be determined in parallel. However, in some embodiments, operating in parallel may result in local tone maps determined based on pixel statistics from a previous frame. Thus, in such embodiments, the pixel contrast control controller may determine local tone maps based at least in part on pixel statistics associated with the current image frame while the pixel contrast control processing circuitry applies local tone maps that are determined based at least in part on pixel statistics associated with a previous image frame. 
     In some embodiments, a set of local tone maps may be spatially and/or temporally filtered to facilitate reducing likelihood of producing unintended sudden brightness changes in an image frame. However, in some embodiments, temporal filtering of successive sets of local tone maps may be disabled when a scene change is detected. In some embodiments, a scene change may be determined from the pixel statistics associated with each local window and/or the entire active region. 
     To enable such an implementation, the pixel contrast control controller may determine multiple versions of each local tone map. For example, the pixel contrast control controller may determine a first version with temporal filtering enabled and a second version with temporal filtering disabled. In this manner, the pixel contrast control processing circuitry may selectively apply either the first version of the local tone maps or the second version of the local tone maps based at least in part on whether a scene change has been detected. 
     Moreover, in some embodiments, the pixel contrast control controller may facilitate reducing power consumption by opportunistically dimming (e.g., reducing) the brightness of a backlight, if equipped. In some embodiments, the dimming factor applied to the backlight level may be temporally filtered (e.g., via a moving average) to facilitate reducing likelihood of producing sudden brightness changes. For example, target luminance of an image frame may be determined based on luminance of a previous image frame and a dimming ratio applied to image frames prior. In this manner, as will be described in more detail below, the techniques described in the present disclosure provide technical benefits that facilitate reducing power consumption and/or improving perceived image quality of electronic displays. 
    
    
     
       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 an electronic device that includes an electronic display, in accordance with an embodiment; 
         FIG. 2  is an example of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 3  is another example of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 4  is another example of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 5  is another example of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 6  is a block diagram of a display pipeline coupled between an image data source and a display driver included in the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 7  is a block diagram of a pixel contrast control block included in the display pipeline of  FIG. 6 , in accordance with an embodiment; 
         FIG. 8  is a flowchart of a process for operating the pixel contrast control block of  FIG. 7 , in accordance with an embodiment; 
         FIG. 9  is a diagrammatic representation of an example image frame, in accordance with an embodiment; 
         FIG. 10  is flowchart of a process for determining pixel statistics, in accordance with an embodiment; 
         FIG. 11  is a flowchart of a process for determining a luma value associated with an image pixel, in accordance with an embodiment; 
         FIG. 12  is a flowchart of a process for operating a controller implemented in the pixel contrast control block of  FIG. 7 , in accordance with an embodiment; 
         FIG. 13  is a flowchart of a process for operating processing circuitry implemented in the pixel contrast control block of  FIG. 7 , in accordance with an embodiment; 
         FIG. 14  is a diagrammatic representation of an example frame grid overlaid on the image frame of  FIG. 9 , in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     To facilitate communicating information, electronic devices often use one or more electronic displays to present visual representations of the information via one or more images (e.g., image frames). Generally, to display an image, an electronic display may control light emission (e.g., luminance) of its display pixels based on corresponding image data. For example, an image data source (e.g., memory, an input/output (I/O) port, and/or a communication network) may output image data as a stream of image pixels, which each indicates target luminance of a display pixel located at a corresponding pixel position. 
     Generally, display pixel luminance may affect perceived brightness and, thus, perceived contrast in an image. At least in some instances, perceived contrast may affect perceived quality of a displayed image. For example, higher perceived contrast may improve edge and/or line sharpness (e.g., definition). 
     However, perceived contrast may also be affected by environmental factors, such as ambient lighting conditions. For example, brighter ambient lighting conditions may result in the difference between perceived brightness of dark display pixels in an image and perceived brightness of bright display pixels in the image decreasing, thereby decreasing perceived contrast in the image. In other words, using the same display pixel luminance, perceived contrast generally changes (e.g., decreases) as ambient lighting conditions change (e.g., increase). 
     To facilitate improving perceived contrast, in some instances, luminance of bright display pixels may be further increased relative to luminance of dark display pixels, for example, to counteract ambient lighting conditions. Generally, an electronic display may increase luminance of its display pixels by increasing electrical power supplied to a light source, such a backlight implemented adjacent the display pixels and/or organic light-emitting diodes (OLEDs) implemented in the display pixels. As such, increasing luminance of display pixels may also increase power consumption resulting from operation of an electronic display. Additionally, the maximum brightness of a light source may limit the ability of an electronic display to continually increase display pixel luminance. 
     Moreover, environmental condition changes often occur relatively suddenly, for example, due to the electronic display being moved from an indoor environment to an outdoor environment. Thus, at least in some instances, responsiveness to environmental condition changes may also affect perceived image quality. For example, adjusting target luminance of display pixels purely in software (e.g., out-of-loop) may result in a perceivable delay before an environmental condition change is accounted for. 
     Accordingly, to facilitate improving perceived image quality and/or reducing power consumption, the present disclosure provides techniques for implementing and operating a pixel contrast control (PCC) block in a display pipeline, for example, coupled between an image data source and a display panel of an electronic display. In some embodiments, the pixel contrast control block may include processing circuitry (e.g., hardware) that modifies image data to adjust resulting color hue and/or luminance in a manner expected to facilitate improving perceived contrast. For example, to modify an image pixel, the pixel contrast control processing circuitry may determine pixel position of the image pixel and apply, to the image pixel, one or more local tone maps each associated with a corresponding pixel position. When multiple (e.g., four nearest) local tone maps are applied, in some embodiments, the pixel contrast control processing circuitry may interpolate the results based at least in part on distance between the pixel position of the image pixel and the pixel positions associated with the local tone maps. 
     Since perceived contrast generally varies with display pixel luminance, in some embodiments, the pixel contrast control processing circuitry may determine pixel statistics, which may be indicative of image content and, thus, used to determine local tone maps. For example, the pixel contrast control processing circuitry may determine local pixel statistics based on local windows (e.g., cells) defined in a current image frame. Additionally, the pixel contrast control processing circuitry may determine global pixel statistics based on an active region defined in the current image frame. 
     To determine global pixel statistics, in some embodiments, the pixel contrast control processing circuitry may define an active region to exclude static portions of a current image frame, such as subtitles. In some embodiments, based on a maximum color component value of each image pixel in the active region, the pixel contrast control processing circuitry may determine a global maximum color component histogram associated with the current image frame. Additionally, based on a luma value associated with each image pixel in the active region, the pixel contrast control processing circuitry may determine a global luma histogram associated with the current image frame. 
     In some embodiments, the luma value associated with an image pixel may be determined based at least in part on a target brightness level. For example, the luma value corresponding with an image pixel may be set as an average luma value (e.g., weighted average of color components) when the target brightness level is below a lower threshold brightness level (e.g., dark to mid-level brightness), a maximum luma value (e.g., maximum of weighted color components) when the target brightness is above an upper threshold brightness level (e.g., high-end of brightness range), and a mixed luma value when the target brightness level is between the lower threshold brightness level and the upper threshold brightness level. In some embodiments, the mixed luma value may be determined by mixing the average luma value and the maximum luma value, for example, to produce a smooth transition therebetween. 
     To determine local pixel statistics, in some embodiments, the pixel contrast control processing circuitry may define one or more sets of local windows in the current image frame, for example, with a first set of local windows defined such that it encloses the active region and a second set of local windows defined such that it is enclosed within the active region. In some embodiments, based on the maximum color component value of each image pixel in a local window (e.g., of the second set), the pixel contrast control processing circuitry may determine the largest maximum color component value and an average maximum color component value associated with the local window. Additionally, based on the luma value associated with each image pixel in a local window (e.g., of the first set), the pixel contrast control processing circuitry may determine a local luma histogram associated with the local window. 
     In this manner, the pixel contrast control block may determine pixel statistics indicative of image content and modify image data in-loop, which, at least in some instances, may facilitate improving responsiveness to environmental condition changes, for example, due to the environmental conditions being considered closer to when images are actually displayed. However, processing duration allocated to the display pipeline and, thus, pixel contrast control processing circuitry is generally limited. To facilitate accounting for its limited allotted processing duration, in some embodiments, the pixel contrast control block may additionally include a controller (e.g., processor) that executes instructions (e.g., firmware) to determine one or more local tone maps based at least in part on detected environmental conditions and the pixel statistics received from the pixel contrast control processing circuitry. 
     In particular, implementing the pixel contrast control block in this manner may enable the pixel contrast control processing circuitry and the pixel contrast control controller to operate in parallel. However, in some embodiments, operating in parallel may result in local tone maps determined based on pixel statistics associated with a current image frame not yet being available when image pixels in the current image frame are to be modified. Thus, in such embodiments, the pixel contrast control controller may determine local tone maps based at least in part on pixel statistics associated with the current image frame while the pixel contrast control processing circuitry applies local tone maps that are determined based at least in part on pixel statistics associated with a previous image frame. 
     For example, based at least in part on the global luma histogram associated the previous image frame and local luma histograms associated with the current image frame, the pixel contrast control controller may determine one or more local tone maps for each local window (e.g., of the first set) to be applied by the pixel contrast control processing circuitry to modify a next image frame. In particular, the one or more local tone maps determined for a local window may be associated with a pixel position located in (e.g., at the center of) the local window. In some embodiments, a set of local tone maps may be spatially filtered to facilitate reducing likelihood of producing unintended sudden brightness changes in an image frame, which, at least in some instances, may facilitate improving perceived image quality. 
     To facilitate further improving perceived image quality, in some embodiments, successive sets of local tone maps may be temporally filtered to facilitate reducing likelihood of producing unintended sudden brightness changes in successive image frames. However, since successive image frames included in different scenes are generally significantly different, applying temporal filtering across a scene boundary may result in an incorrect image frame. To reduce likelihood of perceiving such incorrect image frames, temporal filtering of successive sets of local tone maps may be disabled when a scene change is detected. 
     In some embodiments, the pixel contrast control block may detect that a scene change has occurred between a first image frame and a second image frame based at least in part on scene change statistics (e.g., largest maximum color component value and average maximum color component value) associated with each local window (e.g., of the second set) in the second image frame, for example, relative to scene change statistics associated with the first image frame. As such, the scene change may not be detected until after the pixel contrast control block has completed determination of pixel statistics associated with the second image frame and, thus, after the pixel statistics associated with the second image frame have already been used to determine local tone maps to be applied in the next image frame. While temporally filtered local tone maps may nevertheless be applied in the second image frame, likelihood of producing perceivable visual artifacts may be reduced by applying local tone maps generated with temporal filtering disabled in the next image frame. 
     To enable such an implementation, the pixel contrast control controller may determine multiple versions of each local tone map. For example, the pixel contrast control controller may determine a first version with temporal filtering enabled and a second version with temporal filtering disabled. In this manner, the pixel contrast control processing circuitry may selectively apply either the first version of the local tone maps or the second version of the local tone maps based at least in part on whether a scene change has been detected. 
     Moreover, in some embodiments, the pixel contrast control controller may facilitate reducing power consumption by opportunistically dimming (e.g., reducing) the brightness of a backlight, if equipped, for example in a liquid crystal display (LCD). For example, to reduce the power consumption by the backlight unit, the pixel values may be increased while decreasing (i.e., dimming) the backlight level. As such, the same visual luminance may be provided while maintaining a dimmed backlight level. In some embodiments, the dimming factor applied to the backlight level may be temporally filtered (e.g., via a moving average) to facilitate reducing likelihood of producing sudden brightness changes. For example, target luminance of an image frame may be determined based on luminance of a previous image frame and a dimming ratio applied two image frames prior. In this manner, as will be described in more detail below, the techniques described in the present disclosure provide technical benefits that facilitate reducing power consumption and/or improving perceived image quality of electronic displays. 
     To help illustrate, an electronic device  10 , which includes an electronic display  12 , is shown in  FIG. 1 . As will be described in more detail below, the electronic device  10  may be any suitable electronic device, such as a computer, a mobile phone, a portable media device, a tablet, a television, a virtual-reality headset, a vehicle dashboard, and the like. Thus, 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 an electronic device  10 . 
     In the depicted embodiment, the electronic device  10  includes the electronic display  12 , one or more input devices  14 , one or more input/output (I/O) ports  16 , a processor core complex  18  having one or more processor(s) or processor cores, local memory  20 , a main memory storage device  22 , a network interface  24 , a power source  26 , and image processing circuitry  27 . The various components described in  FIG. 1  may include hardware elements (e.g., circuitry), software elements (e.g., a tangible, non-transitory computer-readable medium storing instructions), or a combination of both hardware and software elements. It should be noted that the various depicted components may be combined into fewer components or separated into additional components. For example, the local memory  20  and the main memory storage device  22  may be included in a single component. Additionally, the image processing circuitry  27  (e.g., a graphics processing unit) may be included in the processor core complex  18 . 
     As depicted, the processor core complex  18  is operably coupled with local memory  20  and the main memory storage device  22 . Thus, the processor core complex  18  may execute instruction stored in local memory  20  and/or the main memory storage device  22  to perform operations, such as generating and/or transmitting image data. As such, the processor core complex  18  may include one or more general purpose microprocessors, one or more application specific integrated circuits (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof. 
     In addition to instructions, the local memory  20  and/or the main memory storage device  22  may store data to be processed by the processor core complex  18 . Thus, in some embodiments, the local memory  20  and/or the main memory storage device  22  may include one or more tangible, non-transitory, computer-readable mediums. For example, the local memory  20  may include random access memory (RAM) and the main memory storage device  22  may include read only memory (ROM), rewritable non-volatile memory such as flash memory, hard drives, optical discs, and/or the like. 
     As depicted, the processor core complex  18  is also operably coupled with the network interface  24 . In some embodiments, the network interface  24  may facilitate communicating data with another electronic device and/or a network. For example, the network interface  24  (e.g., a radio frequency system) may enable the electronic device  10  to communicatively couple to a personal area network (PAN), such as a Bluetooth network, a local area network (LAN), such as an 802.11x Wi-Fi network, and/or a wide area network (WAN), such as a 4G or LTE cellular network. 
     Additionally, as depicted, the processor core complex  18  is operably coupled to the power source  26 . In some embodiments, the power source  26  may provide electrical power to one or more component in the electronic device  10 , such as the processor core complex  18  and/or the electronic display  12 . Thus, the power source  26  may include any suitable source of energy, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. 
     Furthermore, as depicted, the processor core complex  18  is operably coupled with the one or more I/O ports  16 . In some embodiments, I/O ports  16  may enable the electronic device  10  to interface with other electronic devices. For example, when a portable storage device is connected, the I/O port  16  may enable the processor core complex  18  to communicate data with the portable storage device. 
     As depicted, the electronic device  10  is also operably coupled with the one or more input devices  14 . In some embodiments, an input device  14  may facilitate user interaction with the electronic device  10 , for example, by receiving user inputs. Thus, an input device  14  may include a button, a keyboard, a mouse, a trackpad, and/or the like. Additionally, in some embodiments, an input device  14  may include touch-sensing components in the electronic display  12 . In such embodiments, the touch sensing components may receive user inputs by detecting occurrence and/or position of an object touching the surface of the electronic display  12 . 
     In addition to enabling user inputs, the electronic display  12  may include a display panel with one or more display pixels. As described above, the electronic display  12  may control light emission from its display pixels to present visual representations of information, such as a graphical user interface (GUI) of an operating system, an application interface, a still image, or video content, by displaying frames based at least in part on corresponding image data (e.g., image pixel located at the same pixel position). As depicted, the electronic display  12  is operably coupled to the processor core complex  18  and the image processing circuitry  27 . In this manner, the electronic display  12  may display images based at least in part on image data generated by the processor core complex  18 , the image processing circuitry  27 . Additionally or alternatively, the electronic display  12  may display images based at least in part on image data received via the network interface  24 , an input device  14 , and/or an I/O port  16 . 
     As described above, the electronic device  10  may be any suitable electronic device. To help illustrate, one example of a suitable electronic device  10 , specifically a handheld device  10 A, is shown in  FIG. 2 . In some embodiments, the handheld device  10 A may be a portable phone, a media player, a personal data organizer, a handheld game platform, and/or the like. For illustrative purposes, the handheld device  10 A may be a smart phone, such as any iPhone® model available from Apple Inc. 
     As depicted, the handheld device  10 A includes an enclosure  28  (e.g., housing). In some embodiments, the enclosure  28  may protect interior components from physical damage and/or shield them from electromagnetic interference. Additionally, as depicted, the enclosure may  28  surround the electronic display  12 . In the depicted embodiment, the electronic display  12  is displaying a graphical user interface (GUI)  30  having an array of icons  32 . By way of example, when an icon  32  is selected either by an input device  14  or a touch-sensing component of the electronic display  12 , an application program may launch. 
     Furthermore, as depicted, input devices  14  may be accessed through openings in the enclosure  28 . As described above, the input devices  14  may enable a user to interact with the handheld device  10 A. For example, the input devices  14  may enable the user to activate or deactivate the handheld device  10 A, navigate a user interface to a home screen, navigate a user interface to a user-configurable application screen, activate a voice-recognition feature, provide volume control, and/or toggle between vibrate and ring modes. As depicted, the I/O ports  16  may be accessed through openings in the enclosure  28 . In some embodiments, the I/O ports  16  may include, for example, an audio jack to connect to external devices. 
     To further illustrate, another example of a suitable electronic device  10 , specifically a tablet device  10 B, is shown in  FIG. 3 . For illustrative purposes, the tablet device  10 B may be any iPad® model available from Apple Inc. A further example of a suitable electronic device  10 , specifically a computer  10 C, is shown in  FIG. 4 . For illustrative purposes, the computer  10 C may be any Macbook® or iMac® model available from Apple Inc. Another example of a suitable electronic device  10 , specifically a watch  10 D, is shown in  FIG. 5 . For illustrative purposes, the watch  10 D may be any Apple Watch® model available from Apple Inc. As depicted, the tablet device  10 B, the computer  10 C, and the watch  10 D each also includes an electronic display  12 , input devices  14 , I/O ports  16 , and an enclosure  28 . 
     As described above, an electronic display  12  may display images (e.g., image frames) based on image data received, for example, from the processor core complex  18  and/or the image processing circuitry  27 . To help illustrate, a portion  34  of the electronic device  10  including a display pipeline  36  that operationally retrieves, processes, and outputs image data is shown in  FIG. 6 . In some embodiments, a display pipeline  36  may analyze and/or process image data obtained from an image data source  38 , for example, to determine and apply tone curves to the image data before the image data is used to display corresponding images. Additionally, in some embodiments, a display driver  40  may generate and supply analog electrical signals to the display pixels to display an image based at least in part on image data received from the display pipeline  36 . 
     In some embodiments, the display pipeline  36  and/or the display driver  40  may be implemented in the electronic device  10 , the electronic display  12 , or a combination thereof. For example, the display pipeline  36  may be included in the processor core complex  18 , the image processing circuitry  27 , a timing controller (TCON) in the electronic display  12 , one or more other processing units or circuitry, or any combination thereof. Additionally, a controller  42  may be implemented to synchronize and/or supplement processing of the image data received from the image data source  38 . Such a controller may include a processor  44  and/or memory  46 , and may be implemented as separate circuitry or integrated into other components. For example, as with the display pipeline  36 , the controller  42  may be implemented in the electronic device  10 , such as in the processor core complex  18 , the image processing circuitry  27 , one or more other processing units or circuitry, or any combination thereof. 
     In some embodiments, image data may be stored in a source buffer in the image data source  38  and fetched by the display pipeline  36 . In some instances, an electronic device  10  may include one or more processing pipelines (e.g., display pipeline  36 ) implemented to process image data. To facilitate communication between processing pipelines, image data may be stored in the image data source  38 , external from the processing pipelines. In such instances, a processing pipeline, such as the display pipeline  36 , may include a direct memory access (DMA) block that reads (e.g., retrieves) and/or writes (e.g., stores) image data in the image data source  38  (e.g., memory  46 , main memory storage device  22 , and/or local memory). 
     The controller  42  and the display driver  40  may also be operatively coupled to a backlight  48 , if present in the electronic display  12 . In some embodiments, for example such as an electronic devices  10  using a liquid crystal display (LCD), a backlight  48  is included to provide a static or variable light source that acts a light source for the display pixels and, thus, viewing of images. However, in some displays  12 , an alternate light source other than a backlight  48  may be used. For example, organic light emitting diode (OLED) displays may have self-emissive display pixels. Furthermore, some embodiments may include more than one light source, such as self-emissive pixels and a backlight  48 . 
     When retrieved (e.g., fetched) from the image data source  38  by the display pipeline  36 , image data may be formatted in the source space. The source space may include file formats and/or coding native to the image data source  38 . To facilitate display of corresponding images on an electronic display, the display pipeline  36  may map the image data from the source space to a display space used by the electronic display  12 . Different types, models, sizes, and resolution displays may have different display spaces. 
     Additionally, the display pipeline  36  may include one or more image data processing blocks  50  that perform various image processing operations, for example, to map the image data from the source space to the display space. In the depicted embodiment, the image data processing blocks  50  include a pixel contrast control (PCC) block  52  and a dither block  53 . In some embodiments, the image data processing blocks  50  may additionally or alternatively include a color management block, a blend block, a crop block, and/or the like. In some embodiments, a display pipeline  36  may include more, less, combined, split, and/or reordered image data processing blocks  50 . 
     The dither block  53  may assist in smoothing pixel colors and intensities globally and/or locally. These adjustments may assist in compensating for quantization error. For example, a display may not be able to achieve the full color pallet of the image data. Instead of rounding or estimating to the nearest color, the dither block  53  may intertwine colors of the display&#39;s color pallet amongst localized pixels to approximate the original image data and provide a more aesthetic, clear, and/or sharp output for viewing. Additionally or alternatively, the dither block  53  may also provide temporal dithering which may alternate colors and/or light intensities on different images to yield an appearance of a targeted (e.g., desired) color. 
     Based on the characteristics of the display space image data and environmental conditions, such as ambient lighting, the PCC block  52  may analyze image data from the current and/or previous frames and apply local tone maps. In some embodiments, the local tone maps may adjust the color and brightness levels of pixels based on image data characteristics and environmental factors. 
     To help illustrate,  FIG. 7  is a block diagram of the PCC block  52  receiving input image data  54  and producing output image data  56 . The input image data  54  of the upcoming frame may be analyzed by a statistics sub-block  58  to obtain pixel statistics  60 . These pixel statistics  60  may include minimums, maximums, averages, histograms, and/or other information indicative of content of the input image data  54 . Additionally, pixel statistics  60  may be determined globally and/or locally. The pixel statistics  60  may be processed by a PCC controller  62  to determine local tone maps  64  to adjust the image input data  54  in the pixel modification sub-block  66 . Output image data  56  may then be further processed and/or sent to the display driver  40 . 
     In some embodiments the PCC block  52  may be divided into more than one processing sections. For example, the statistics sub-block  58  and the pixel modification sub-block  66  may be implemented by pixel contrast control processing circuitry (e.g., hardware) and the PCC controller  62  may be implemented a processor that executes instructions (e.g., firmware) stored in a tangible, non-transitory, computer-readable medium. In some embodiments, the PCC controller  62  may include a dedicated processor or microprocessor. Additionally or alternatively, the PCC controller  62  may share processing resources with the controller  42 , processor core complex  18 , or the like. 
     In some embodiments, the statistics sub-block  58  may communicate an interrupt signal to the PCC controller  62  when pixel statistics  60  are available for processing. Additionally, after determining the local tone maps  64  based at least in part on the pixel statistics  60 , the PCC controller  62  may store the local tone maps  64  in registers accessible by the pixel modification sub-block  66 . Additionally, to facilitate synchronizing operation the PCC controller  62  may indicate to the pixel modification sub-block  66  that the local tone maps  64  have been updated and ready to be applied. 
       FIG. 8  is a flow diagram  68  illustrating an overview of the operation of the PCC block  52 . The PCC block  52  receives input image data  54  for a frame (process block  70 ) and determines one or more active regions in the frame (process block  72 ). The active region(s) may be areas of the frame that are desired to be considered for controlling perceived contrast. The statistics sub-block  58  of the PCC block  52  may then determine global statistics for the active region (process block  74 ). One or more sets of local windows of the frame may also be determined (process block  76 ) such that local statistics for each local window may be determined (process block  78 ). From the global and local statistics, local tone maps  64  may then be determined (process block  80 ) and applied to the input image data  54  (process block  82 ). 
     To help illustrate,  FIG. 9  is an example image frame  84  of the input image data  54  in which an active region  86  is defined. As stated above, the active region  86  may be an area of the image frame  84  that is to include PCC processing separately from the rest of the image frame  84 . For example, active regions  86  may exclude or be separated from areas of the image frame  84  that including subtitles, constant color sections (e.g., letterboxes), and/or the like. Additionally, an active region  86  may include a portion of the image frame  84  separated via picture-in-pictures or split-screen. In some embodiments, the active region  86  may include the full image frame  84 . 
     In any case, one or more sets of local windows  88  may be defined based at least in part on the active region  85 . For example, a first set may be defined to completely enclose the active region  86 . In fact, in some embodiments, the first set may include edge windows  90  that encompass portions of the image frame  84  outside the active region  86 . Although pixel statistics  60  are to be drawn from the portion of the edge windows  90  within the active region  86 , in some embodiments, pixel statistics  60  may nevertheless be gathered from outside the active region  86 . 
     Additionally or alternatively, a second set may be defined such that it is completely enclosed within the active region  86 . In some embodiments, the local windows  88  included in the second set may be used to facilitate detecting occurrence of scene changes. Additionally, in some embodiments, the local windows  88  included in the second set may differ from the local windows  88  included in the first set, for example, such that they are aligned and/or offset differently. In other embodiments, a single set of local windows  88  may be used. 
     As stated above, local and global statistics may be determine by the statistics sub-block  58 . Additionally, both local and global statistics may include maxima, averages, histograms, and/or other desired pixel statistics  60 .  FIG. 10  is a block diagram  94  outlining an example of a process for determining pixel statistics  60 . Input image data  54  may be received by the statistics sub-block  58  (process block  96 ). The input image data  54  may image pixels that each indicates target luminance of each color components (e.g., red, green, and blue) located at a corresponding display pixel. 
     In finding one set of pixel statistics  60 , the maximum intensity level of the color components for each pixel is determined (process block  98 ). Each pixel&#39;s maximum intensity level may be from any of the color components (e.g., red, green, or blue) and used to produce both local and global statistics. The maximum intensity levels of each pixel in a local window  88  may be used to find the overall maximum intensity level as well as an average intensity level among the maximum, average maximum (process block  100 ). As stated above, the determined pixel statistics  60  are then sent to the PCC controller  62  for computation of local tone maps  64  (process block  102 ). In some embodiments, each maximum intensity level may be encoded into a maximum gamma value for the corresponding pixel (process block  104 ). This encoding may transform the color component intensity levels into a non-linear space to increase perceptible differences to the human eye. Whether using the maximum intensity levels or maximum gamma values a global histogram of the maxima may be created (process block  106 ), and sent to the PCC controller  62  (process block  102 ). 
     Additionally or alternatively, the color component intensities of the full input image data  54  may be encoded into gamma values before gathering further statistics (process block  108 ). The gamma values, or color component intensities if encoding is not desired, may also be used to determine luma values for each image pixel (process block  110 ). Luma values may correspond to the luminance or light emission of a corresponding display pixel. As such, correction coefficients may be used for different color components. 
     In some embodiments, a maximum luma value of the different color components and/or an average luma value among the different color components of each image pixel may be computed. Furthermore, a mixture of maximum and average luma values may also computed to smooth transitions between light and dark temporally and/or spatially. In some embodiments a floor value may be established for the average luma values and/or the mixed luma values to maintain at least a minimum luma level. These maximum luma values, average luma values, and mixed luma values may be used to calculate global histograms, throughout the active region  86  (process block  112 ) and/or local histograms, among each of the local windows  88  (process block  114 ). Additionally, in some embodiments, a filter, (e.g., low-pass) may be applied to one or more histograms (e.g., local histograms) to facilitate smoothing spatial outliers (process block  116 ) before being sent to the PCC controller  62  (process block  102 ). 
     As stated above, the average, maximum, and/or mixed luma values may be used by the PCC controller  62  to generate local tone maps  64 . In some instances, the input image data  54  may include highly saturated colors. While having a high color content, the light output of highly saturated colors may not be very high. 
       FIG. 11  is a flowchart  118  to help illustrate choosing which luma value to use. A target brightness level of a pixel, local window  88 , or active region  86  may be determined (process block  120 ). This target brightness level may be determined based on the desired light output of a pixel, local window  88 , or active region  86 . As such, the luma value for each image pixel may be chosen individually, grouped by local window  88 , grouped by active region  86 , or together as an image frame  84 . If the target brightness is less than a lower threshold (decision block  122 ), then the luma value may be set as the average luma value (process block  124 ). If the target brightness is greater than an upper threshold (decision block  126 ), then the luma value may be set as the maximum luma value (process block  128 ). Furthermore, if the target brightness level is between the thresholds, the luma value may be set to the mixed luma value. In some embodiments, it may be desirable to use the maximum luma values instead of the mixed or average luma values when generating local tone maps  64 , since using a maximum luma value may reduce color component changes. However, average and/or mixed luma values may yield a boost in grey level, thereby preserving perceived contrast by making relatively more changes to the color component intensities. 
     Once received, the PCC controller  62  may generate local tone maps  64  based at least in part on the pixel statistics  60 .  FIG. 12  is a flowchart  132  illustrating the creation of local tone maps  64 . The PCC controller  62  may determine environmental conditions (e.g., ambient lighting) to factor into the local tone maps  64  (process block  134 ). The PCC controller  62  also receives the pixel statistics  60  from the statistics sub-block  58  (process block  136 ). From the environmental conditions and pixel statistics  60  (e.g., global maximum histogram, global luma histogram, local histograms, etc.), the PCC controller  62  may determine a dimming factor (process block  138 ) and tone maps (process block  140 ). In some embodiments, the local tone maps  64  may be filtered, for example by using a low-pass filter, to facilitate smoothing color component and light output intensities (process block  142 ). These local tone maps  64  may then be sent to the pixel modification sub-block  66  for application to the input image data  54 . Local tone maps  64  may be applied per pixel or via local windows  88  and/or active regions  86 . Additionally, in some embodiments, the dimming factor may be used to affect the backlight  48  of the electronic display  12 , if equipped, or the current and/or voltage levels to self-emissive display pixels. A further temporal filter may be applied to such lighting effects to reduce the likelihood of sudden lighting changes. 
     To produce the local tone maps  64 , the PCC controller  62  may employ temporal and/or spatial filters. For example, temporal filters may allow for smooth light output changes (e.g., backlight  48  changes) as well as color component factor changes. Additionally, temporal filters may allow for smooth tone curve changes over time. In some embodiments, a temporal filter may use pixel statistics  60  from one or more previous frames. However, due to the effects of temporal filtering, if a scene change occurs, artifacts and/or undesired changes in color or lighting effects may occur if the temporal filtering is not reset. Scene change identification may be done as part of a pixel statistic (e.g., global statistic) analysis. For example, if the global histogram of the input image data  54  is significantly different from that of the previous frame, a scene change may have occurred. 
     Returning now to  FIG. 7 , as stated above, the statistics sub-block  58  provides the pixel statistics  60  to the PCC controller  62  to generate the local tone maps  64 . In some embodiments, the PCC block  52  may collect the pixel statistics  60  and interpolate the output image data  54  simultaneously. As such, this may lead to the use local tone maps  64  determined based on pixel statistics  60  associated with a previous frame to image data corresponding with the current frame. The temporal filters may facilitate smoothing any differences between frames  84 . However, a scene change may not be detected until the subsequent frame. As such, when a scene change occurs, this frame delay may be compounded with the above mentioned artifacts or undesired color and/or lighting effect changes due to temporal filtering. As temporal filtering may be accomplished over multiple frames, it may take multiple frames to correct the issues that arise. 
     To minimize the effects of a scene change, two sets of tone maps may be generated by the PCC controller  62 . One set of local tone maps  64  may include temporal filtering from previous frames  84 , while a second set of local tone maps  64  may have the temporal filters reset, thereby not taking previous frames  84  into account. While temporally filtered local tone maps  64  may nevertheless be applied, when a scene change is detected, the likelihood of producing perceivable visual artifacts may be reduced by applying local tone maps  64  without temporal filtering. This may result in the single frame delay artifacts as outlined above without added delay due to temporal filtering. In some embodiments, faster processing may reduce the frame delay further. Furthermore, in general, a single frame outlier may be acceptable when perceived by the human eye depending on implementation (e.g., frame rate). 
     To help further illustrate,  FIG. 13  is a flowchart  144  showing example operation of the pixel modification sub-block  66 . The pixel modification sub-block  66  may receive both temporally filtered and non-temporally filtered local tone maps  64  (process block  146 ). It may then be determined if a scene change has occurred (decision block  148 ). If a scene change has occurred, the non-temporally filtered local tone maps  64  are applied to the input image data  54  (process block  150 ), and temporally filtered local tone maps  64  are applied if a scene change is not detected (process block  152 ). In some embodiments, if a scene change is detected, a different weighting of temporally filtered tone maps  64  and/or non-temporally filtered local tone maps  64  may be applied. When applying the appropriate local tone maps  64 , pixel modification sub-block  66  may interpolate the tone mapped image data (process block  154 ). 
     The tone mapped image data, output image data  56 , may be interpolated spatially within the active region  86  to smooth interfaces and boundaries as shown by the frame grid  156  of  FIG. 14 . The local tone maps  64  may be specified on a two-dimensional frame grid  156  of interior pixel positions  158 , which lie within the active region  86 , and exterior pixel positions  160 , which lie outside the active region  86 . Although the frame grid  156  need not align with the local windows  88 , in some embodiments, the interior pixel position  158  correspond to the center of the local windows  88 . 
     In any case, the pixel modification sub-block  66  may receive one or more local tone maps  64  corresponding with each interior pixel position  158 . For image pixels that lie in the active region  86 , one or more (e.g., four) surrounding local tone maps  64  may be applied and the results interpolated based at least in part on the distances between the local tone maps  64  to determine output image data  56 . For image pixels outside the active region  86 , the input image data  54  may merely be copied to the output image data  56 . Similarly, if the PCC block  52  is disabled, output image data  56  may be the same as the input image data  54 . 
     If it becomes desirable to disable the PCC block  52 , a further temporal filter may be applied to the light output level in an exit phase. Because the PCC block  52  may have adjusted the light output level (e.g., backlight  48  level, self-emissive pixel level, etc.), the exit phase may slowly ramp up or down as desired to avoid sharp changes in light output level. Similarly, an entry phase may also temporally adjust the light output level to adjust the level as desired. Additionally, an entry phase may skip pixel interpolation for one or more frames until pixel statistics  60  have been collected. 
     When enabled, the PCC block  52  operates to increase the perceived contrast level of the frames  84  shown on the electronic display  12  while taking into account the environmental factors, such as ambient light. Depending on the type of electronic display  12  (e.g., OLED, LCD, plasma, etc.), further benefits can also be gained as well. For example, some displays  12  (e.g., LCD) may yield power savings by reducing the output level of a backlight  48  controlled separately from the pixels. 
     Although the above referenced flow charts are shown in a given order, in certain embodiments, decision and process blocks may be reordered, altered, deleted, and/or occur simultaneously. Additionally, the referenced flow charts are given as illustrative tools and further decision and process blocks may also be added as desired. 
     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. 
     The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Metadata:
Filing Date: 20180312
Publication Date: 20191210
Grant Date: 20191210
Priority Date: 20180312
Inventors: CHAPPALLI, MAHESH B.
MIN, CHANGKI
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2360/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3233", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/106", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0271", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G3/3648", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0686", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/2007", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3233", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0271", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3208", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/2007", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/106", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0271", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3233", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/2007", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0686", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/2007", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/106", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0271", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0686", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0653", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/103", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 65012087