PATENT DOCUMENT

Publication Number: US-12211457-B1
Application Number: US-202318475077-A
Country: US
Kind Code: B1

Title: Dynamic quantum dot color shift compensation systems and methods

Abstract:
A device may include an electronic display having multiple illuminators that generate light at a first wavelength and a quantum dot layer that converts a portion of the light from the first wavelength to a second wavelength. The first wavelength may vary based on a brightness level of the illuminator, and the amount of light generated by the illuminator that is converted to the second wavelength may vary based on the first wavelength. The electronic display may also include a display pixel to regulate the light emitted from the electronic display at a pixel location based on compensated image data. The device may also include image processing circuitry to determine a luminance contribution to the light from the illuminator for the pixel location, determine per color component compensation values based on the luminance contribution, and generate the compensated image data based on the per color component compensation values.

Claims:
What is claimed is: 
     
       1. A device comprising:
 an electronic display comprising:
 a plurality of illuminators configured to generate light at a first wavelength, wherein the first wavelength of an illuminator of the plurality of illuminators varies based on a brightness level of the illuminator; 
 a quantum dot layer configured to convert a portion of the light from the first wavelength to a second wavelength, wherein an amount of the portion of the light generated by the illuminator converted to the second wavelength varies based on the first wavelength; and 
 a display pixel configured to regulate the light emitted from the electronic display at a pixel location based on compensated image data; and 
 
 image processing circuitry configured to:
 determine a luminance contribution to the light from the illuminator for the pixel location; 
 determine per color component compensation values based on the luminance contribution; and 
 generate the compensated image data based on the per color component compensation values. 
 
 
     
     
       2. The device of  claim 1 , wherein the image processing circuitry is configured to:
 determine a plurality of luminance contributions to the light from two or more illuminators of the plurality of illuminators for the pixel location, wherein the two or more illuminators comprises the illuminator; 
 determine a summed luminance contribution of the two or more illuminators by summing at least a portion of the plurality of luminance contributions; and 
 determine the per color component compensation values based on the summed luminance contribution. 
 
     
     
       3. The device of  claim 2 , wherein the image processing circuitry is configured to:
 determine a luminance compensation based on the summed luminance contribution; 
 combine the luminance compensation and the summed luminance contribution to generate a corrected luminance contribution; and 
 determine the per color component compensation values based on the corrected luminance contribution. 
 
     
     
       4. The device of  claim 2 , wherein the plurality of luminance contributions comprises a first component contribution, a second component contribution, and a third component contribution for each illuminator of the two or more illuminators, wherein summing at least the portion of the plurality of luminance contributions comprises summing the first component contribution of each of the two or more illuminators. 
     
     
       5. The device of  claim 4 , wherein the first component contribution comprises a luma component contribution, the second component contribution comprises a first chromatic component contribution, and the third component contribution comprises a second chromatic component contribution. 
     
     
       6. The device of  claim 1 , wherein the first wavelength comprises blue visible light. 
     
     
       7. The device of  claim 6 , wherein the second wavelength comprises red visible light or green visible light. 
     
     
       8. The device of  claim 1 , wherein the image processing circuitry comprises a hardware pipeline having dedicated color shift compensation circuitry configured to generate, at least in part, the compensated image data. 
     
     
       9. The device of  claim 1 , wherein the plurality of illuminators comprises a plurality of light emitting diodes (LEDs) configured to generate the light at the first wavelength. 
     
     
       10. The device of  claim 9 , wherein the quantum dot layer comprises a silicon microcrystal configured to convert the portion of the light from the first wavelength to the second wavelength. 
     
     
       11. Image processing circuitry having color shift compensation circuitry configured to:
 receive pixel values corresponding to a pixel of a quantum dot display panel at a pixel location; 
 determine a plurality of luminance contributions to light from a respective plurality of illuminators of a quantum dot backlight of the quantum dot display panel for the pixel location; 
 determine one or more color compensation values based on the plurality of luminance contributions; 
 determine a compensated color of the light from the quantum dot backlight at the pixel location based on the one or more color compensation values; 
 determine pixel compensation values based on the compensated color of the light from the quantum dot backlight at the pixel location; and 
 modify the pixel values based on the pixel compensation values. 
 
     
     
       12. The image processing circuitry of  claim 11 , wherein determining the one or more color compensation values comprises:
 summing at least a portion of the plurality of luminance contributions to generate a total luma value, wherein the portion of the plurality of luminance contributions comprises luminance contributions to a luma component of the light from the quantum dot backlight at the pixel location; and 
 determining the one or more color compensation values based on the total luma value. 
 
     
     
       13. The image processing circuitry of  claim 12 , wherein determining the one or more color compensation values comprises referencing a look-up-table indexed by the total luma value. 
     
     
       14. The image processing circuitry of  claim 12 , wherein the one or more color compensation values comprise a luma compensation value, a first chromatic compensation value, and a second chromatic compensation value. 
     
     
       15. The image processing circuitry of  claim 14 , wherein the compensated color of the light comprises a compensated luma component based on the luma compensation value and the total luma value, a first compensated chromatic component based on the first chromatic compensation value, and a second compensated chromatic component based on the second chromatic compensation value. 
     
     
       16. The image processing circuitry of  claim 11 , wherein determining the one or more color compensation values comprises determining a color compensation value for each color component of each illuminator of the plurality of illuminators, and wherein the color shift compensation circuitry is configured to:
 combine the color compensation value for each color component of each illuminator of the plurality of illuminators with respective components of the plurality of luminance contributions to generate a set of compensated luminance contributions for each illuminator of the plurality of illuminators, wherein the set of compensated luminance contributions for each illuminator comprises a compensated luma contribution value, a first compensated chromatic contribution value, and a second compensated chromatic contribution value; and 
 determine the compensated color based on respective sums of the compensated luma contribution value, the first compensated chromatic contribution value, and the second compensated chromatic contribution value of each of the plurality of illuminators. 
 
     
     
       17. The image processing circuitry of  claim 11 , wherein the color shift compensation circuitry is configured to:
 convert the compensated color of the light to a color space of the pixel values; 
 determine a difference between the compensated color of the light and a target color of the light in the color space of the pixel values; and 
 determine the pixel compensation values based on the difference. 
 
     
     
       18. A non-transitory, machine-readable medium comprising instructions, wherein, when executed by one or more processors, the instructions cause the one or more processors to perform operations or to cause the one or more processors to control image processing circuitry to perform the operations, wherein the operations comprise:
 receiving pixel values corresponding to a pixel of a quantum dot display panel at a pixel location; 
 determining a plurality of luminance contributions to light from a respective plurality of illuminators of a quantum dot backlight of the quantum dot display panel for the pixel location; 
 determining one or more color compensation values based on the plurality of luminance contributions; 
 determining a compensated color of the light from the quantum dot backlight at the pixel location based on the one or more color compensation values; 
 determining pixel compensation values based on the compensated color of the light from the quantum dot backlight at the pixel location; and 
 modifying the pixel values based on the pixel compensation values. 
 
     
     
       19. The non-transitory, machine-readable medium of  claim 18 , wherein determining the one or more color compensation values comprises:
 summing at least a portion of the plurality of luminance contributions to generate a total luma value, wherein the portion of the plurality of luminance contribution comprises luminance contributions to a luma component of the light from the quantum dot backlight at the pixel location; and 
 determining the one or more color compensation values based on the total luma value. 
 
     
     
       20. The non-transitory, machine-readable medium of  claim 19 , wherein determining the plurality of luminance contributions of the plurality of illuminators comprises multiplying normalized contributions to the light from the plurality of illuminators by respective brightnesses of the plurality of illuminators.

Description:
BACKGROUND 
     The present disclosure relates generally to image processing and, more particularly, to compensating for a color shift associated with changes in backlight brightness. 
     Electronic devices often use one or more electronic displays to present visual information such as text, still images, and/or video by displaying one or more images. 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 of its display pixels based at least in part on corresponding image data. 
     In other words, an image to be displayed may be represented by image data defining luminance values for pixels of the display, and the pixels may emit light that, in the aggregate, form the image. For example, one or more backlights may generate light for several different pixels, and each pixel may allow a portion of the generated light to be emitted based on a luminance value of the image data corresponding to the pixel. However, in some scenarios, the color of the light generated by a backlight may vary at different brightness levels, which may cause undesired visual artifacts such as discolorations to appear. 
     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. 
     An electronic display may include one or more backlights that provide light to multiple pixels. Using the light generated by the backlight, pixels may control the luminance output that is emitted from the electronic display per color component to regulate the amount and/or color of light emitted according to image data. In some embodiments, the brightness of the backlight may be modulated to adjust the overall brightness of the display or a portion thereof. However, in some scenarios, changing the brightness of the backlight may lead to a color shift in the generated light. As such, the change in color of the backlight may cause the luminance levels for one or more color components to be different from the corresponding image data, leading to visible image artifacts (e.g., discolorations). In particular, the backlight of a quantum dot display panel may generate different color light at different brightness levels. 
     A quantum dot backlight may include multiple illuminators (e.g., light emitting diodes (LEDs)) that produce light at a particular color. Additionally, the quantum dot backlight may include one or more quantum dot layers that change a portion of light generated by the illuminators into different color light (e.g., different wavelengths of light). Together, the generated light and the converted light may provide a balanced (e.g., white) combined light with a known (e.g., expected) spectrum that can be regulated (e.g., via pixels programmed via image data) to display an image. 
     Additionally, in some embodiments, different brightness levels may be achieved by increasing or decreasing the luminance output of the illuminators by changing the power (e.g., current and/or voltage) provided thereto. However, the output color (e.g., wavelength) of the illuminators may be different at different brightness levels, such as achieved by applying different amounts of current thereto. Furthermore, the quantum dot layers may be sensitive to changes in the generated light such that the amounts (e.g., intensities) of converted light may change with the wavelength of the generated light. As such, the spectrum (e.g., intensity vs. color component/wavelength) of the combined light output from the quantum dot backlight may be different at different brightness levels. In other words, the color of the quantum dot backlight may shift based on the brightness level. 
     In some embodiments, image processing circuitry such as a color shift compensation block may compensate for the different output colors of the backlight at different brightness levels. The color shift compensation block may increase and/or decrease the relative values of the red, blue, and/or green pixel values of the image data to compensate for the different color combined light of the quantum dot backlight. For example, the color shift associated with an increase in brightness may increase the converted red and green color components of the combined light relative to the generated blue light, which may give the generated light of the backlight an increased yellowish hue. As such, the color shift compensation block may determine how much color shift is exhibited at a pixel location and compensate the image data (e.g., by increasing a blue component and/or by decreasing the red and green components) such that perceivable artifacts, such as discolorations are reduced or eliminated. 
    
    
     
       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 the form of a handheld device, in accordance with an embodiment; 
         FIG.  3    is another example of the electronic device of  FIG.  1    in the form of a tablet device, in accordance with an embodiment; 
         FIG.  4    is another example of the electronic device of  FIG.  1    in the form of a computer, in accordance with an embodiment; 
         FIG.  5    is another example of the electronic device of  FIG.  1    in the form of a watch, in accordance with an embodiment; 
         FIG.  6    is another example of the electronic device of  FIG.  1    in the form of a computer, in accordance with an embodiment; 
         FIG.  7    is a block diagram of the image processing circuitry of  FIG.  1    including a color shift compensation (CSC) block, in accordance with an embodiment; 
         FIG.  8    is a schematic diagram of a portion of a quantum dot display panel, in accordance with an embodiment; 
         FIG.  9    is a graph of changes in wavelength of light generated by a quantum dot illuminator with respect to the current applied thereto, in accordance with an embodiment; 
         FIG.  10    is a graph of the intensities of different wavelengths of light produced by a quantum dot backlight at different brightnesses, in accordance with an embodiment; 
         FIG.  11    is a schematic diagram of the CSC block of  FIG.  7   , in accordance with an embodiment; and 
         FIG.  12    is a flowchart of an example process for compensating input pixel values to account for a color shift associated with different quantum dot backlight brightnesses, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     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 may 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. Furthermore, the phrase A “based on” B is intended to mean that A is at least partially based on B. Moreover, the term “or” is intended to be inclusive (e.g., logical OR) and not exclusive (e.g., logical XOR). In other words, the phrase A “or” B is intended to mean A, B, or both A and B. 
     Electronic devices often use electronic displays to present visual information. 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 controls the luminance (and, as a consequence, the color) of its display pixels based on corresponding image data received at a particular resolution. For example, an image data source may provide image data as a stream of pixel data, in which data for each pixel indicates a target luminance (e.g., brightness and/or color) of one or more display pixels located at corresponding pixel positions. In some embodiments, image data may indicate luminance per color component, for example, via red component image data, blue component image data, and green component image data, collectively referred to as RGB image data (e.g., RGB, sRGB). Additionally or alternatively, image data may be indicated by a luma channel and one or more chrominance channels (e.g., XYZ, YCbCr, YUV, etc.), grayscale (e.g., gray level), or other color basis. It should be appreciated that a luma channel, as disclosed herein, may encompass linear, non-linear, and/or gamma-corrected luminance values. 
     Additionally, the image data may be processed to account for one or more physical or digital effects associated with displaying the image data. For example, image data may be compensated for pixel aging (e.g., burn-in compensation), cross-talk between electrodes within the electronic device, transitions from previously displayed image data (e.g., pixel drive compensation), warps, contrast control, and/or other factors that may cause distortions or artifacts perceivable to a viewer. 
     In some embodiments, the electronic display may include one or more backlights or other illuminators that provide light to multiple pixels. For example, the electronic display may include a single backlight, multiple backlights controlled together, or multiple backlights controlled individually (e.g., according to location on the electronic display and/or according to color component). Using the light generated by the backlight, pixels may control the luminance output that is emitted from the electronic display per color component to regulate the amount and/or color of light emitted according to image data. As used herein, the term “backlight” may refer to a single illuminator or multiple illuminators working in conjunction with one another, controlled individually or in one or more groups, to provide light to pixels of an electronic display. 
     In some embodiments, the brightness of the backlight may be modulated to adjust the overall brightness of the display or a portion thereof. However, in some scenarios, changing the brightness of the backlight may lead to a color shift in the generated light. As such, the change in color of the backlight may cause the luminance levels for one or more color components to be different from the corresponding image data, leading to visible image artifacts (e.g., discolorations). In particular, the backlight of a quantum dot display panel may generate different color light at different brightness levels. 
     A quantum dot backlight may include multiple illuminators (e.g., light emitting diodes (LEDs)) that produce light at a particular color. For example, in some embodiments, the illuminators may generate blue light, such as at a particular wavelength (e.g., 450 nanometers (nm) plus or minus 1 nm, plus or minus 2 nm, plus or minus 5 nm, plus or minus 10 nm, plus or minus 25 nm and so on). Additionally, the quantum dot backlight may include one or more quantum dot layers that change a portion of light generated by the illuminators into different color light (e.g., different wavelengths of light). For example, a quantum dot layer may utilize semiconductor crystals (e.g., nanocrystals) to change a portion of the blue generated light into light of different colors, such as red (e.g., 630 nm plus or minus 1 nm, plus or minus 2 nm, plus or minus 5 nm, plus or minus 10 nm, plus or minus 25 nm and so on) and green (e.g., 530 nm plus or minus 1 nm, plus or minus 2 nm, plus or minus 5 nm, plus or minus 10 nm, plus or minus 25 nm and so on). Together, the generated light and the portions of converted light may provide a balanced (e.g., white) combined light with a known (e.g., expected) spectrum that can be regulated (e.g., via pixels programmed via image data) to display an image. 
     Additionally, in some embodiments, different brightness levels may be achieved by increasing or decreasing the luminance output of the illuminators by changing the power (e.g., current and/or voltage) provided thereto. However, the output color (e.g., wavelength) of the illuminators may be different (e.g., by up to 0.5 nm, up to 1 nm, up to 2 nm, up to 5 nm, up to 10 nm, etc.) at different brightness levels (e.g., associated with different currents). Furthermore, the quantum dot layers may be sensitive to changes in the generated light such that the amounts (e.g., intensities) of converted light may change with the wavelength of the generated light. As such, the spectrum (e.g., intensity vs. color component/wavelength) of the combined light output from the quantum dot backlight may be different at different brightness levels. In other words, the color of the quantum dot backlight may shift based on the brightness level. As should be appreciated, the illuminators (e.g., the color and wavelength thereof) and the relative changes in wavelength by the quantum dot layer(s) may depend on implementation, and the present techniques may be utilized with any suitable quantum dot display panel exhibiting color shifts at different brightness levels. 
     Embodiments of the present disclosure may include image processing circuitry such as a color shift compensation block to compensate for the different output colors of the backlight at different brightness levels. The color shift compensation block may increase and/or decrease the relative values of the red, blue, and/or green pixel values of the image data to compensate for the different color combined light of the quantum dot backlight. For example, the color shift associated with an increase in brightness may increase the converted red and green color components of the combined light relative to the generated blue light, which may give the generated light of the backlight an increased yellowish hue. As such, the color shift compensation block may determine how much color shift is exhibited at a pixel location and compensate the image data (e.g., by increasing a blue component and/or by decreasing the red and green components) such that the color shift is less or not perceivable (e.g., the emitted light from the display panel is indicative of the desired image). 
     With the foregoing in mind,  FIG.  1    is an example electronic device  10  with an electronic display  12  having independently controlled color component illuminators (e.g., projectors, backlights, etc.). As 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 wearable device such as a watch, a vehicle dashboard, or 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 . 
     The electronic device  10  may include one or more electronic displays  12 , input devices  14 , input/output (I/O) ports  16 , a processor core complex  18  having one or more processors or processor cores, local memory  20 , a main memory storage device  22 , a network interface  24 , a power source  26 , and image processing circuitry  28 . 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. As should be appreciated, the various 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. Moreover, the image processing circuitry  28  (e.g., a graphics processing unit, a display image processing pipeline, etc.) may be included in the processor core complex  18  or be implemented separately. 
     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 instructions stored in local memory  20  or the main memory storage device  22  to perform operations, such as generating or transmitting image data to display on the electronic display  12 . 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 program instructions, the local memory  20  or the main memory storage device  22  may store data to be processed by the processor core complex  18 . Thus, the local memory  20  and/or the main memory storage device  22  may include one or more tangible, non-transitory, computer-readable media. 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, or the like. 
     The network interface  24  may communicate data with another electronic device 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, or a wide area network (WAN), such as a 4G, Long-Term Evolution (LTE), or 5G cellular network. 
     The power source  26  may provide electrical power to operate the processor core complex  18  and/or other components in the electronic device  10 . 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. 
     The I/O ports  16  may enable the electronic device  10  to interface with various other electronic devices. The input devices  14  may enable a user to interact with the electronic device  10 . For example, the input devices  14  may include buttons, keyboards, mice, trackpads, and the like. Additionally or alternatively, the electronic display  12  may include touch sensing components that enable user inputs to the electronic device  10  by detecting occurrence and/or position of an object touching its screen (e.g., surface of the electronic display  12 ). 
     The electronic display  12  may display a graphical user interface (GUI) (e.g., of an operating system or computer program), an application interface, text, a still image, and/or video content. The electronic display  12  may include a display panel with one or more display pixels to facilitate displaying images. Additionally, each display pixel may represent one of the sub-pixels that control the luminance of a color component (e.g., red, green, or blue). As used herein, a display pixel may refer to a collection of sub-pixels (e.g., red, green, and blue subpixels) or may refer to a single sub-pixel. 
     As described above, the electronic display  12  may display an image by controlling the luminance output (e.g., light emission) of the sub-pixels based on corresponding image data. In some embodiments, pixel or image data may be generated by an image source, such as the processor core complex  18 , a graphics processing unit (GPU), or an image sensor (e.g., camera). Additionally, in some embodiments, image data may be received from another electronic device  10 , for example, via the network interface  24  and/or an I/O port  16 . Moreover, in some embodiments, the electronic device  10  may include multiple electronic displays  12  and/or may perform image processing (e.g., via the image processing circuitry  28 ) for one or more external electronic displays  12 , such as connected via the network interface  24  and/or the I/O ports  16 . 
     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 smartphone, such as an IPHONE® model available from Apple Inc. 
     The handheld device  10 A may include an enclosure  30  (e.g., housing) to, for example, protect interior components from physical damage and/or shield them from electromagnetic interference. The enclosure  30  may surround, at least partially, the electronic display  12 . In the depicted embodiment, the electronic display  12  is displaying a graphical user interface (GUI)  32  having an array of icons  34 . By way of example, when an icon  34  is selected either by an input device  14  or a touch-sensing component of the electronic display  12 , an application program may launch. 
     Input devices  14  may be accessed through openings in the enclosure  30 . Moreover, 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. Moreover, the I/O ports  16  may also open through the enclosure  30 . Additionally, the electronic device may include one or more cameras  36  to capture pictures or video. In some embodiments, a camera  36  may be used in conjunction with a virtual reality or augmented reality visualization on the electronic display  12 . 
     Another example of a suitable electronic device  10 , specifically a tablet device  10 B, is shown in  FIG.  3   . 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  30 . The electronic display  12  may display a GUI  32 . Here, the GUI  32  shows a visualization of a clock. When the visualization is selected either by the input device  14  or a touch-sensing component of the electronic display  12 , an application program may launch, such as to transition the GUI  32  to presenting the icons  34  discussed in  FIGS.  2  and  3   . 
     Turning to  FIG.  6   , a computer  10 E may represent another embodiment of the electronic device  10  of  FIG.  1   . The computer  10 E may be any suitable 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  10 E may be an iMac®, a MacBook®, or other similar device by Apple Inc. of Cupertino, California. It should be noted that the computer  10 E may also represent a personal computer (PC) by another manufacturer. A similar enclosure  30  may be provided to protect and enclose internal components of the computer  10 E, such as the electronic display  12 . In certain embodiments, a user of the computer  10 E may interact with the computer  10 E using various peripheral input devices  14 , such as a keyboard  14 A or mouse  14 B, which may connect to the computer  10 E. 
     As described above, the electronic display  12  may display images based at least in part on image data. Before being used to display a corresponding image on the electronic display  12 , the image data may be processed, for example, via the image processing circuitry  28 . In general, the image processing circuitry  28  may process the image data for display on one or more electronic displays  12 . For example, the image processing circuitry  28  may include a display pipeline, memory-to-memory scaler and rotator (MSR) circuitry, warp compensation circuitry, or additional hardware or software means for processing image data. The image data may be processed by the image processing circuitry  28  to reduce or eliminate image artifacts, compensate for one or more different software or hardware related effects, and/or format the image data for display on one or more electronic displays  12 . As should be appreciated, the present techniques may be implemented in standalone circuitry, software, and/or firmware, and may be considered a part of, separate from, and/or parallel with a display pipeline or MSR circuitry. 
     To help illustrate, a portion of the electronic device  10 , including image processing circuitry  28 , is shown in  FIG.  7   . The image processing circuitry  28  may be implemented in the electronic device  10 , in the electronic display  12 , or a combination thereof. For example, the image processing circuitry  28  may be included in the processor core complex  18 , a timing controller (TCON) in the electronic display  12 , or any combination thereof. As should be appreciated, although image processing is discussed herein as being performed via a number of image data processing blocks, embodiments may include general purpose and/or dedicated hardware or software components to carry out the techniques discussed herein. 
     The electronic device  10  may also include an image data source  38 , a display panel  40 , and/or a controller  42  in communication with the image processing circuitry  28 . In some embodiments, the display panel  40  of the electronic display  12  may be a reflective technology display, a liquid crystal display (LCD), or any other suitable type of display panel  40 . In some embodiments, the controller  42  may control operation of the image processing circuitry  28 , the image data source  38 , and/or the display panel  40 . To facilitate controlling operation, the controller  42  may include a controller processor  44  and/or controller memory  46 . In some embodiments, the controller processor  44  may be included in the processor core complex  18 , the image processing circuitry  28 , a timing controller in the electronic display  12 , a separate processing module, or any combination thereof and execute instructions stored in the controller memory  46 . Additionally, in some embodiments, the controller memory  46  may be included in the local memory  20 , the main memory storage device  22 , a separate tangible, non-transitory, computer-readable medium, or any combination thereof. 
     The image processing circuitry  28  may receive source image data  48  corresponding to a desired image to be displayed on the electronic display  12  from the image data source  38 . The source image data  48  may indicate target characteristics (e.g., pixel data) corresponding to the desired image using any suitable source format, such as an RGB format, an αRGB format, a YCbCr format, and/or the like. Moreover, the source image data may be fixed or floating point and be of any suitable bit-depth. Furthermore, the source image data  48  may reside in a linear color space, a gamma-corrected color space, or any other suitable color space. As used herein, pixels or pixel data may refer to a grouping of sub-pixels (e.g., individual color component pixels such as red, green, and blue) or the sub-pixels themselves. 
     As described above, the image processing circuitry  28  may operate to process source image data  48  received from the image data source  38 . The image data source  38  may include captured images from cameras  36 , images stored in memory, graphics generated by the processor core complex  18 , or a combination thereof. Additionally, the image processing circuitry  28  may include one or more sets of image data processing blocks  50  (e.g., circuitry, modules, or processing stages) such as a color shift compensation (CSC) block  52 . As should be appreciated, multiple other processing blocks  54  may also be incorporated into the image processing circuitry  28 , such as a color management block, a dither block, a pixel contrast control (PCC) block, a burn-in compensation (BIC) block, a scaling/rotation block, etc. before and/or after the CSC block  52 . The image data processing blocks  50  may receive and process source image data  48  and output display image data  56  in a format (e.g., digital format and/or resolution) interpretable by the display panel  40 . Further, the functions (e.g., operations) performed by the image processing circuitry  28  may be divided between various image data processing blocks  50 , and, while the term “block” is used herein, there may or may not be a logical or physical separation between the image data processing blocks  50 . 
     As discussed further herein, in some embodiments, the CSC block  52  may compensate image data for color shifts associated with brightness changes to the electronic display  12 . As should be appreciated, a brightness setting may define a global luminance output of the electronic display  12 . Indeed, while display pixels of an electronic display  12  vary the luminance and/or color outputs therefrom depending on the image data, the brightness setting (e.g., a display brightness value (DBV), global brightness setting, etc.) may regulate the overall brightness (e.g., total luminance output) of the electronic display  12  by increasing or decreasing an amount of light generated by a backlight of the display panel  40 . For example, the voltages and/or currents provided to illuminators of the backlight may be increased to increase the brightness level of electronic display  12 , such as based on the brightness setting. As should be appreciated, the brightness setting may be obtained/determined based on numerous factors such as but not limited to ambient lighting (e.g., received via an ambient light sensor), time of day, panel age, and/or a user setting. 
     In some embodiments, the electronic display  12  may include a quantum dot display panel  58  with multiple illuminators  60  (e.g., light emitting diodes (LEDs)) that produce light for a grid  62  of pixel locations  64 , as shown in  FIG.  8   . As should be appreciated, the number, layout, and relative sizes of the illuminators  60  and pixel locations  64  of the grid  62  are shown for illustrative purposes only and are, as such, non-limiting. In general, a quantum dot display panel  58  may utilize multiple illuminators  60  distributed across the display panel  40  to produce generated light  66  at a particular color. For example, in some embodiments, the generated light  66  may be blue light at a particular wavelength (e.g., 450 nanometers (nm) plus or minus 1 nm, plus or minus 2 nm, plus or minus 5 nm, plus or minus 10 nm, plus or minus 25 nm and so on). Additionally, the quantum dot display panel  58  may include one or more quantum dot layers  68  that change a portion of generated light  66  of the illuminators  60  into different color light (e.g., different wavelengths of light). For example, a quantum dot layer  68  may utilize semiconductor crystals (e.g., nanocrystals) to change a portion of blue generated light  66  into different colors, such as red converted light  70 A (e.g., 630 nm plus or minus 1 nm, plus or minus 2 nm, plus or minus 5 nm, plus or minus 10 nm, plus or minus 25 nm and so on) and green converted light  70 B (e.g., 530 nm plus or minus 1 nm, plus or minus 2 nm, plus or minus 5 nm, plus or minus 10 nm, plus or minus 25 nm and so on), cumulatively converted light  70 . Together, the generated light  66  and converted light  70  may provide a balanced (e.g., white) combined light  72  with a known (e.g., expected) spectrum that can be regulated via a pixel layer  74  (e.g., of display pixels) based on the display image data  56 . The pixel layer  74  may include display pixels that regulate a transmissivity of different color components. Moreover, as used herein, a display pixel may refer to a single color component display pixel or a group of sub-pixels including multiple color component display pixels (e.g., a red display pixel, a blue display pixel, and a green display pixel). Furthermore, as used herein, the quantum dot display panel  58  includes a quantum dot backlight including the illuminators  60  and the quantum dot layer(s)  68 . As should be appreciated, the different converted lights  70  (e.g., red converted light  70 A and green converted light  70 B) may be produced in a single quantum dot layer  68  or in individual quantum dot layers  68 . Moreover, as should be appreciated, the illuminator  60 , quantum dot layer  68 , and pixel layer  74  of  FIG.  8    are shown as functional layers and may or may not be linearly stacked, and there may or may not be physical distinctions therebetween. For example, one or more layers, such as the pixel layer  74  and the quantum dot layer  68 , may be formed together. 
     Furthermore, in some embodiments, different brightness levels may be achieved by increasing or decreasing the luminance output of the illuminators  60  by changing the power (e.g., current and/or voltage) provided thereto. However, the color (e.g., wavelength) of the generated light  66  from the illuminators  60  may be different (e.g., by up to 0.5 nm, up to 1 nm, up to 2 nm, up to 5 nm, up to 10 nm, up to 25 nm, and so on) at different brightness levels. For example,  FIG.  9    is a graph  76  of the wavelength  78  of the generated light  66  from an illuminator  60  relative to an applied current  80  to the illuminator  60 . As should be appreciated, the wavelength  78  and the applied current  80  of the graph  76  are normalized and may be indicative of any color and/or type of illuminator  60 . Indeed, as the applied current  80  is increased, such as to increase the brightness level (e.g., luminance output), the wavelength  78  of the generated light  66  may also change. As such, the change in brightness level may alter the color of the combined light  72  produced by the backlight. 
     Furthermore, the quantum dot layer(s)  68  may be sensitive to changes in the generated light  66  such that the amounts (e.g., intensities) of converted light  70  may change with the wavelength of the generated light  66 . To help illustrate,  FIG.  10    is a graph  82  of the relative intensity  84  of the wavelengths  78  of the combined light  72 - 1  at a first brightness level (BL1) and the combined light  72 - 2  a second brightness level (BL2). Indeed, the spectrum (e.g., intensity  84  vs. color component/wavelength  78 ) of the combined light  72  output from the quantum dot backlight may be different at different brightness levels. In other words, the color of the quantum dot backlight may shift based on the brightness level. As should be appreciated, the illuminators  60  (e.g., the color and wavelength thereof) and the relative changes in wavelength  78  by the quantum dot layer(s)  68  may depend on implementation, and the present techniques may be utilized with any suitable quantum dot display panel  58  exhibiting color shifts (e.g., color differences) at different brightness levels. 
     As discussed above, the brightness of the backlight may be modulated to adjust the overall brightness of the electronic display  12  or a portion thereof. However, changing the brightness of the backlight may lead to a color shift in the generated light  66  and/or the intensities  84  of the converted light  70  and, therefore, the combined light  72 . The change in color of the combined light  72 , if uncompensated, may cause visible image artifacts (e.g., discolorations). As such, in some embodiments, a portion of the image processing circuitry  28  such as the color shift compensation block  52  may compensate for the different output colors of the quantum dot backlight at different brightness levels. Indeed, the color shift compensation block  52  may increase and/or decrease the relative values of the red, blue, and/or green pixel values of the image data (e.g., display image data  56 ) to compensate for the different color combined light  72  of the quantum dot backlight. For example, the color shift associated with an increase in brightness may increase the red converted light  70 A and the green converted light  70 B color components of the combined light  72  relative to the blue generated light  66 , which may increase/produce a yellowish hue in the combined light  72 . As such, the color shift compensation block  52  may determine how much color shift is exhibited at a pixel location  64  and compensate the image data (e.g., by increasing a blue component and/or by decreasing the red and green components) such that the color shift is less or not perceivable. 
     Returning briefly to  FIG.  8   , In some embodiments, the backlight of the quantum dot display panel  58  may include multiple illuminators  60  controlled together (e.g., in one or more groups) or controlled individually (e.g., according to location on the electronic display  12 ). For example, illuminators  60  along edges of the electronic display  12  may be maintained at a reduced brightness level relative to illuminators  60  closer to the center of the electronic display  12 , such as part of vignetting or other effect. Furthermore, a pixel location of interest  86  (e.g., corresponding to a display pixel of the pixel layer  74 ) may receive light contributions from multiple illuminators  60  (e.g., illuminators  60 A- 60 I). In other words, the combined light  72  regulated by a pixel at a pixel location of interest  86  may be sourced (e.g., directly and/or indirectly via the quantum dot layer(s)  68 ) from multiple illuminators  60 . As such, the color of the combined light  72  received from the multiple different illuminators  60  may or may not be uniform. For example, illuminators  60  closer to a pixel location of interest  86 , such as illuminator  60 E, may provide a higher contribution of combined light  72  to the pixel location of interest  86  than an illuminator  60  further from the pixel location of interest  86 , such as illuminator  60 G. In some embodiments, contributions from different illuminators  60  may be considered separately and/or in an aggregate when generating compensations to image data for shifts in the color of the combined light  72  at a pixel location of interest  86 . 
     To help illustrate,  FIG.  11    is a schematic diagram of a portion of the color shift compensation block  52  that receives input pixel values  88 , implements a pixel modification  90  to compensate for color shifts of the quantum dot backlight, and outputs compensated pixel values  92 . In some embodiments, the color shift compensation block  52  may obtain the luminance contributions  94  of one or more illuminators  60  for a pixel location of interest  86 . For example, the luminance contributions  94  may be measures of how much light (e.g., combined light  72 ) is attributable to different illuminators  60 , such as based on the relative locations of the illuminators  60  and the pixel location of interest  86 . Moreover, in some embodiments, the luminance contributions  94  may be normalized to sum to one for the pixel location of interest  86 . In some embodiments, the luminance contributions  94  may include contributions from all of the illuminators  60  of the quantum dot display panel  58  or a subset thereof. For example, such a subset may include 9 illuminators, 16 illuminators, 108 illuminators, or any suitable number of illuminators  60  depending on implementation. Moreover, illuminators  60  included in the subset may be those that contribute greater than a threshold amount of luminance to the pixel location of interest  86 , within a threshold distance from the pixel location of interest  86 , and/or be fixed relative to the portion of the grid  62  surrounding the pixel location of interest  86 . 
     The luminance contributions  94  (e.g., normalized luminance contributions) based on locations of the illuminators  60  may be multiplied by their corresponding brightness  96  to achieve the luma contribution values  98  (e.g., Y channel color components of a chromatic color space such as XYZ, YUV, YCbCr, etc.) of each illuminator  60 . Additionally, conversion profiles  100 A and  100 B (cumulatively  100 ) of the quantum dot layer(s)  68  that convert portions of the generated light  66  to converted light  70  may be used to obtain the chromatic channel contributions  102 A and  102 B, respectively, to the combined light  72  of the illuminators  60 . As discussed above, the illuminators  60  may be controlled separately (e.g., independently or in groups) and, therefore, may have different brightnesses  96 . As such, each illuminator  60  may have separate color shifts contributing to the combined light  72  at the pixel location of interest  86 . As such, in some embodiments, the luma contribution value  98  of each illuminator  60  may be used to obtain color corrections  104  (e.g., compensations) to the luma contribution contribution values  98  and chromatic channel contributions  102 A and  102 B. For example, quantum dot compensation circuitry  106  may utilize an algorithm, look-up-table, or other technique to generate the color corrections  104  based on the luma contribution values  98  of the illuminators  60 . The color corrections  104  for each color component (e.g., luma contribution value  98  and chromatic channel contributions  102 A and  102 B) of each illuminator  60  may be combined (e.g., multiplied as a gain and/or added as an offset) with the respective luma contribution values  98  and chromatic channel contributions  102 A and  102 B of the illuminators to achieve the corrected (e.g., estimated to be the actual output) luma contribution values and chromatic channel contributions for each illuminator  60 , and the corrected contributions of each illuminator  60  may be summed to generate a corrected total luma value  108  and corrected total chromatic components  110 A and  110 B, the combination of which is estimated to be the actual color of the combined light  72  at the pixel location of interest  86 . 
     As should be appreciated, obtaining color corrections  104  for each illuminator  60  assumed to have a contribution at the pixel location of interest  86  may include performing such calculations for many (e.g., greater than 3, greater than 20, greater than 100, etc.) illuminators  60 , which may be hardware and/or software resource intensive. In some embodiments, the luma contribution values  98  and chromatic channel contributions  102 A and  102 B may be respectively summed, prior to computing the color corrections  104 , to obtain a total luma value  112  and total chromatic components  114 A and  114 B. The color corrections  104  may then be determined (e.g., via the quantum dot compensation circuitry  106 ) based on the total luma value  112 . By performing the sum before computing the color corrections  104 , the number of color corrections  104  and associated computations may be reduced for increased efficiency. The color corrections  104  based on the total luma value  112  may be combined (e.g., multiplied as a gain and/or added as an offset) with the respective total luma value  112  and total chromatic components  114 A and  114 B to obtain the corrected total luma value  108  and the corrected total chromatic components  110 A and  110 B. 
     Based on the corrected color (e.g., defined by the corrected total luma value  108  and the corrected total chromatic components  110 A and  110 B) of the quantum dot backlight at the pixel location of interest  86 , the color shift compensation block  52  may determine the pixel modification  90  to the input pixel values  88 , such as via pixel compensation circuitry  116 . For example, in some embodiments, the corrected total luma value  108  and the corrected total chromatic components  110 A and  110 B may be converted to an RGB color space (e.g., via an XYZ to RBG conversion  118 ) or other color space of the input pixel values  88 . Moreover, in some embodiments, the target RGB color (e.g., the estimated color of the combined light  72  at the corrected total luma value  108  if no color shift occurred) may be determined (e.g., via a target RGB conversion  120 ). The target RGB color and corrected color of the combined light  72  in RGB format may be used (e.g., via a compensation calculation  122 ) to determine pixel corrections  124  (e.g., pixel compensations to the image data) for each of the RGB color components of the input pixel values  88 . As should be appreciated, while discussed herein as in the RGB color space, any suitable color space, such as the color space of the input pixel values  88  may be utilized (e.g., converted to and used for calculating the pixel corrections  124 ). Moreover, the pixel corrections  124  may be calculated as gains and/or offsets to be combined (e.g., multiplied and/or added, respectively) during pixel modification  90  to generate the compensated pixel values  92 . 
     As should be appreciated, portions of the pixel compensation circuitry  116  are shown as examples, and additional, fewer, and/or different conversions and calculations may be used therein to determine the pixel corrections  124 . Moreover, in some embodiments, one or more aspects of the color shift compensation block  52  may be combined and/or implemented together. For example, the quantum dot compensation circuitry  106  and pixel compensation circuitry  116  may be implemented together (e.g., in hardware, software, or a combination thereof) such that the pixel corrections  124  are determined based on the total luma value  112  or the collection of multiple luma value contributions  98  for the pixel location of interest  86 . 
     To help further illustrate,  FIG.  12    is a flowchart  126  of an example process for compensating input pixel values  88  to account for a color shift associated with different quantum dot backlight brightnesses. In some embodiments, the color shift compensation block  52  may determine brightnesses of illuminators  60  of a quantum dot backlight of a quantum dot display panel  58  (process block  128 ). Additionally, the color shift compensation block  52  may determine per color component (e.g., in an XYZ or other chromatic color space) contributions (e.g., luma contributions values  98  and chromatic channel contributions  102 ) of the quantum dot illuminators  60  for a pixel location of interest  86  based on the brightnesses (process block  130 ). For example, normalized luminance contributions  94  may be used along with the brightnesses of individual illuminators  60  to determine luma contribution values  98 , and the luma contribution values  98  may be used along with conversion profiles  100  to determine chromatic channel contributions  102 . Additionally, the per color component contributions (e.g., luma contributions values  98  and chromatic channel contributions  102 ) may be summed, respectively, to obtain per color component total luminance intensities (e.g., a total luma value  112  and total chromatic components  114 ) for the pixel location of interest  86  (process block  132 ). Additionally, the color shift compensation block  52  may determine per color component color corrections  104  based on a total luma value  112  of a luma channel of the per color component total luminance intensities (process block  134 ). The per color component color corrections  104  and the per color component total luminance intensities (e.g., total luma value  112  and total chromatic components  114 ) may be combined (e.g., via summation or multiplication) to obtain per color component corrected luminance intensities (e.g., corrected total luma value  108  and the corrected total chromatic components  110 ) for the pixel location of interest  86  (process block  136 ). As should be appreciated, the per color component corrected luminance intensities may, cumulatively, be indicative of the estimated color of the combined light  72  at the pixel location of interest  86 . Based on the per color component corrected luminance intensities, per color component pixel corrections  124  (e.g., compensations) may be determined for the pixel location of interest  86  (process block  140 ). Moreover, input pixel values  88  for a display pixel corresponding to the pixel location of interest  86  may be compensated based on the per color component pixel corrections  124  to generate compensated pixel values  92  (process block  142 ). 
     As discussed herein, a color shift compensation block  52  of image processing circuitry  28  may reduce the likelihood of image artifacts (e.g., discoloration) due to color shifts in a quantum dot backlight at different brightnesses. Although the above flowchart  126  is shown in a given order, in certain embodiments, process/decision blocks may be reordered, altered, deleted, and/or occur simultaneously. Additionally, the flowchart  126  is given as an illustrative tool and further decision and process blocks may also be added depending on implementation. 
     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. 
     It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     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: 20230926
Publication Date: 20250128
Grant Date: 20250128
Priority Date: 20230926
Inventors: CHAPPALLI, MAHESH B
KORNIENKO, ALEXEY
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G3/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3413", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3413", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 94377091