Method and apparatus for controlling image dimming on display apparatus

Abstract

An apparatus and method for controlling image reproduction on a color display having an array of pixels. The method enables global brightness control / dimming using one of current control, rolling update duty cycle control, pulse width modulation, and / or active control using a liquid crystal layer that utilizes variable color domain lookup table mapping to compensate for wavelength shifts of the emitted light.

Description

Technical Field

[0001] This invention relates to an apparatus and method for controlling image reproduction on a color display. Specifically, it is used to provide global dimming in a miniature LED display. Background Technology

[0002] III-V semiconductor materials are of particular interest for semiconductor device design, especially III-nitride semiconductor materials.

[0003] "III-V group" semiconductors include binary, ternary, and quaternary alloys of group III elements such as Ga, Al, and In and group V elements such as N, P, As, and Sb, and have attracted great interest in many applications, including electronics and optoelectronics.

[0004] Of particular interest is the category of semiconductor materials known as "Group III nitrides," which includes gallium nitride (GaN), indium nitride (InN), and aluminum nitride (AlN), as well as their ternary and quaternary alloys. (Al,In)GaN is a term encompassing AlGaN, InGaN, and GaN. Group III nitride materials have achieved commercial success not only in solid-state lighting and power electronics but also demonstrate specific advantages in quantum light sources and photomatter interactions.

[0005] While various group III nitride materials have gained commercial attention, gallium nitride (GaN) is widely regarded as one of the most important new semiconductor materials and is of particular interest for many applications.

[0006] This invention can be implemented primarily using LEDs formed from GaN and InGaN, but is advantageously applicable to LEDs containing alternative group III nitride material combinations.

[0007] It is known that introducing porosity into bulk group III nitrides such as GaN can significantly affect their material properties (optical, mechanical, electrical, and thermal). Therefore, the possibility of adjusting a wide range of material properties by changing the porosity of GaN and group III nitride semiconductors has made porous GaN of great interest in optoelectronic applications.

[0008] In a significant improvement over known tri-color LED displays, the applicant, Poro Technologies Ltd, has developed variable-wavelength LEDs formed from group III nitride semiconductor materials grown over porous regions of group III nitride materials. Instead of known LEDs that emit monochromatic light, these variable-wavelength LEDs can emit a broad spectrum of different emission wavelengths in response to variations in the driving conditions provided to them. These variable-wavelength LEDs and methods for their manufacture are disclosed in International Patent Application No. PCT / GB2022 / 051997, published as WO2023 / 007174.

[0009] Because the peak emission wavelength of such variable-wavelength LEDs can be adjusted by changing the driving conditions, a single variable-wavelength LED can replace multiple "monochrome" subpixels. In a particularly preferred embodiment, an LED can be adjusted to emit any of red, green, or blue light by adjusting the driving conditions provided to the same variable-wavelength LED. This means that a color display can be formed from an array of variable-wavelength LEDs, where each variable-wavelength LED acts as a color-variable pixel, or alternatively as a color-variable subpixel in a subpixelated display.

[0010] The ability of variable wavelength LEDs to emit this wide range of wavelengths makes the display driving and calibration procedures significantly more complex than those for known RGB subpixel displays. Summary of the Invention

[0011] This invention is defined in the independent technical solutions which are hereby referred to. Preferred or advantageous features of this invention are defined in the appended appendices.

[0012] The present invention preferably utilizes a display device comprising a plurality of variable wavelength LEDs. In a preferred embodiment, such a display device includes an array of variable wavelength LEDs, wherein each variable wavelength LED forms a pixel of the display device.

[0013] An example of a variable wavelength LED that can be used in this invention is known as the Dynamic Pixel Adjustment (DPT®) variable wavelength LED from ProTech Corporation, which is disclosed in International Patent Application No. PCT / GB2022 / 051997, published as WO2023 / 007174.

[0014] By altering the driving conditions (driving current and / or driving voltage) supplied to a variable wavelength LED, a continuous spectrum of different emission wavelengths spanning a range of emission wavelengths can be directly emitted from that LED. In the CIE xy color space, a variable wavelength LED can emit any color along a continuous wavelength curve. The length and shape of the emitting wavelength lines in the CIE xy color space are determined by the LED's composition and structure, as described in WO2023 / 007174.

[0015] One way to control the wavelength of light emitted by a variable-wavelength LED is to provide a continuously variable drive current to the LED. When a display device receives a signal identifying a target color to be displayed by a given variable-wavelength LED, it can then deliver a drive current to that pixel at any amount required for the LED to emit a specific wavelength from its continuous spectrum of emitting wavelengths. However, this method has disadvantages such as the difficulty in consistently and precisely controlling the variable drive current, and the limitation that variable-wavelength LEDs can only display chromaticity within a continuous line of emission wavelengths that can be directly emitted by the LED.

[0016] An alternative method for driving variable-wavelength LEDs is to select a set of predetermined "primary colors" (primary color wavelengths) from the continuous spectrum of emission wavelengths that can be emitted by the variable-wavelength LED. Instead of controlling the emission wavelength to any point within the entire range of emissible colors, a finite set of operating points can be created by selecting multiple (N) primary color wavelengths from the range of emissible colors. Each of the N primary colors is then used as a predetermined operating point for the variable-wavelength LED, and the N individual driving conditions required to generate those N primary color wavelengths are programmed into the display device equipped with the variable-wavelength LED.

[0017] N primary color wavelengths selected from the emission wavelength range of an LED form a color palette of N usable primary colors, allowing a variable wavelength LED to emit light at any time using one of these N predetermined primary color wavelengths. The N usable primary colors define multiple color gamuts that can display colors, because any color within this color gamut can be displayed by a variable wavelength LED by mixing the usable primary color wavelengths.

[0018] When a display device receives a signal identifying a target color to be displayed by a given variable wavelength LED, the device can select a smaller set of two or more primary colors from a palette of N available primary colors. These primary colors can be mixed to represent the target color. The selection of which primary colors from the N available primary colors depends on the wavelength of the target color to be displayed.

[0019] By driving LEDs to emit light only at multiple "primary color" wavelengths, rather than any wavelength from a continuous spectrum that can be directly emitted, display devices can display additional chromaticity that variable-wavelength LEDs cannot directly emit. Primary color wavelengths can be mixed using color mixing techniques known to existing displays, so that the overall color observed by the viewer is a temporal and / or spatial combination of the emitted primary colors, rather than a single color "directly" emitted by a single variable-wavelength LED. Driving variable-wavelength LEDs to emit light at predetermined "primary color" wavelengths also advantageously simplifies driving requirements because, instead of providing a continuously variable drive current, the display device can be calibrated to deliver a more manageable set of N predetermined drive conditions that produce N usable primary colors.

[0020] The number of primary colors "N" available can be selected depending on the desired color gamut size and the required complexity of the control system. A larger number N results in a larger color gamut, but also requires a larger number of driving conditions and more complex control requirements. Since variable wavelength LEDs can emit a continuous wavelength range, N can be chosen as any number up to infinity (N = infinity is equivalent to continuously driving to any point within the emitting wavelength range). N is preferably greater than 3 so that the displayed color gamut is large enough to represent a wide range of colors. Particularly preferably, N is greater than or equal to 4, 5, or 6 to cover a large color gamut while keeping control requirements relatively simple. Preferably, N can be less than or equal to 8, 10, or 12 to prevent the control requirements from becoming overly complex.

[0021] In a preferred embodiment of the display device, each variable wavelength LED is a pixel of the device, and the display device is a field-sequence display. In this embodiment, the same variable wavelength LED pixel is driven by discrete driving conditions corresponding to multiple discrete primary color emission wavelengths, thereby driving the LED pixel to emit the primary color wavelength in a sequential sub-frame.

[0022] In sequential field displays, by supplying different driving conditions to the same variable-wavelength LED within sequential sub-frames of the display frame, the LED can be controlled to emit multiple discrete primary color emission wavelengths one after another. In this way, the same variable-wavelength LED can emit multiple pixels with selected "primary color emission wavelengths" one after another within the duration of a single display frame. During each individual sub-frame, the pixel emits only one primary color emission wavelength. Due to the persistence of vision in the human observer, the primary color wavelengths emitted during the sequential sub-frames are averaged over time, so that the color observed by an individual viewing the display at a normal viewing distance is a mixture of the colors emitted during the display frame.

[0023] In a subpixelated display, different primary color emission wavelengths can be emitted by individual subpixels. All subpixels can be variable wavelength LEDs, or some subpixels can be non-variable wavelength LEDs.

[0024] The brightness or grayscale of the emitted light can be changed by shortening or lengthening the duty cycle (pulse width) of the drive current pulses supplied to the LEDs in the display, thus altering the LED's "on-time". In field-sequence displays, the maximum duty cycle is achieved when the drive current supplied to the variable-wavelength LED is continuously allocated to the display frame or sub-frame of the color being emitted for 100% of its duration. Although controlling the amount of drive current supplied to the variable-wavelength LED determines the emitted wavelength, the duty cycle of the drive current pulses must also be variable to achieve variable display brightness, adding an extra layer of complexity to device control.

[0025] In ProTech's Dynamic Pixel Adjustment (DPT®) variable wavelength LEDs, the peak emission wavelength of the variable wavelength LED is largely dependent on the magnitude of the electrical drive signal supplied to a given LED, and longer wavelengths of emitted color require lower values ​​of drive current / voltage, which inherently produces lower brightness. This poses a challenge for situations requiring high display brightness, and also presents a challenge to color balance when mixing naturally bright shorter wavelengths with naturally darker longer wavelengths. Detailed Implementation

[0026] Figure 1 The diagram illustrates a CIE xy color space plot 100, on which wavelengths that can be emitted by a variable wavelength LED are indicated by a continuous black line 101. By changing the driving conditions supplied to the LED, such as the magnitude of the driving current or driving voltage, the wavelength of the light directly emitted by the LED can be adjusted to any wavelength along line 101.

[0027] Figure 2 Plotting the CIE xy color space 200, its illustration is similar to... Figure 1 The same emission line 101 shown in the diagram overlaps with six points representing "primary colors" P1, P2, P3, P4, P5, and P6. These six primary colors are specific emission wavelengths selected from the continuous emitting wavelength line 101. Six individual driving conditions required to supply the variable wavelength LED to generate these six emission wavelengths can be readily found and incorporated into the display device. During operation, these six driving conditions are supplied to the variable wavelength LED, causing the LED to emit light at any of the six primary color wavelengths. The space defined by the six primary colors constitutes the color gamut that can be displayed using the variable wavelength LED and these six primary color wavelengths.

[0028] By using field-sequence driving to drive the variable-wavelength LED, different driving conditions can be supplied to the LED during discrete sub-frame periods. Therefore, during the first sub-frame period, a first driving condition can be supplied to the LED, causing the LED to emit light at the primary color wavelength P1. During subsequent sub-frame periods, different driving conditions can be supplied to the LED, causing the LED to emit light at different primary color wavelengths (one of P2 to P6). In a preferred embodiment, each display frame contains only two sub-frames, each assigned to the emission of a different primary color. The overall color observed by an observer viewing the variable-wavelength LED will be the time average of the two primary color wavelengths emitted during the display frame period.

[0029] It is possible to divide a display frame into any number of shorter sub-frames. For example, a display frame could be divided into six sub-frames, allowing each of the six primary colors to be emitted one after another within the display frame. However, the inventors have found it desirable to use only two of the available primary colors during a given display frame, as this simplifies color mixing and reduces power consumption when switching between driving conditions. To render a given target color, two primary color wavelengths are selected from the available color palette of the six primary colors P1 to P6, and then the two selected primary colors are mixed proportionally to give a time-averaged value that appears to the observer as the target color.

[0030] like Figure 3 As illustrated, the six available primary colors P1 to P6 can be divided into multiple pairs. Each pair of primary colors can then be linearly mixed with each other to display any color along the straight line 301 between the two primary color wavelengths.

[0031] However, as from Figure 3 It is also evident that using a limited set of primary colors (e.g., N=6) means that not all colors within the color gamut are located on the linear blending line 301 between a pair of primary colors. Therefore, with such a small available primary color palette, not all colors in the color gamut can be formed by just one pair of primary colors.

[0032] Display panels formed by variable-wavelength pixels or monochrome (sub)pixels with fixed emission wavelengths will have different requirements for both grayscale control (controlling the brightness of a given pixel channel) and global brightness control (proportionally adjusting the brightness of the entire display panel). It is desirable for micro-LED displays to provide global brightness control while minimizing any potential impact on grayscale control and the ability to mix colors using multiple available primary colors.

[0033] Global brightness control via current

[0034] For displays formed by monochrome pixels with a fixed emission wavelength, grayscale is typically controlled by pulse width modulation (PWM), and global brightness can then be set by current. Due to the data loading time associated with program nodes, there is usually a limitation of ~8 bits per pixel, which means that adding dimming capability solely through PWM is not feasible.

[0035] However, controlling the dimming range by modulating the applied current to provide global brightness control is simple. This is generally avoided for micro-LED displays because of the strong interaction between the dominant wavelength and the applied current—reducing the current to provide dimming also shifts the emitted wavelength, thus affecting the display's color reproduction. Advantageously, compared to known GaN or AlInGaP, porous GaN has been found to exhibit a relatively weak change in dominant wavelength with current.

[0036] This wavelength shift diagram is shown in... Figure 4 In the color space plot 400, specifically, it can be seen that for a given change in current, the wavelength shift 410 of the red LED is much wider than the wavelength shift 420 of the green LED or the wavelength shift 430 of the blue LED. Regardless of the magnitude of the wavelength shift, the effect will be that the color gamut of the display changes with the global dimming level.

[0037] Display devices typically use a mapping from the source color gamut (usually sRGB) to the display color gamut. This is usually achieved by pre-filling a 3D lookup table (3D LUT) of the source color gamut to display color gamut mapping. In the case of micro-LEDs, the 3D LUT will need to be modified with dimming levels to compensate for color gamut changes at different dimming levels. Preferably, the correction of the 3D LUT will ensure that the mapping between the source and color gamut is constant in tone, regardless of the dimming level, so that changes in color gamut volume do not affect the tonal appearance.

[0038] Global brightness control using rolling updates

[0039] Alternatively, global brightness can be controlled by controlling the number of pixel rows that are "on" simultaneously in the display array. This is often referred to as "rolling updates," where a column band (e.g.) can be turned on and this band can then move forward on the display array. The fewer columns that are turned on simultaneously, the shorter the duty cycle of each pixel will be, and therefore the dimmer the light output of the display.

[0040] This advantage means that the current supply remains constant when a pixel is "on," and therefore there is no need to consider wavelength shift. Depending on the display resolution, this provides very fine global brightness control, because turning on all rows simultaneously will provide 100% global brightness output, while turning on only a single row of the scroll bar will provide approximately 0.1% global brightness.

[0041] Global brightness control of variable wavelength LEDs

[0042] Variable wavelength LEDs, such as those described above, typically use PWM to control grayscale and use the current applied to the pixels to control the color of the light emitted by each pixel. The global color channel brightness (and therefore, the white point) is controlled by the number of rows updated simultaneously. The minimum grayscale time depends on the number of rows updated simultaneously in a given color channel.

[0043] In this configuration, PWM can be used for global brightness control if it is acceptable to reduce the number of grayscale control levels provided by PWM control. The reduction in grayscale control levels can be compensated for by introducing spatial dithering to synthesize the missing grayscale control. Using high-quality dithering algorithms, this can be made virtually imperceptible to the human eye. The finite MTF of the projection optics in the display device can also help hide dithering artifacts by providing a degree of blurring.

[0044] In one example of a PWM scheme providing 8-bit (256 levels) grayscale control, 255 of these levels can be dedicated to providing global brightness control, with each individual level (i.e., "off" or "on") providing grayscale. Using spatial dithering, the number of on pixels in a given area can be used to control the grayscale brightness of the color in that area. This can be seen in the comparison between the following two: using 8-bit grayscale for each of the red, green, and blue channels... Figure 5 The image; and the image rendered using 1-bit grayscale for each of the red, green, and blue channels. Figure 6 Similarly, 8-bit grayscale is used to represent each of the red, green, and blue channels. Figure 7 The test image was rendered using 1-bit grayscale for each of the red, green, and blue channels. Figure 8 As pixel sizes in displays become smaller (i.e., the number of pixels per inch increases), spatial jitter becomes increasingly perceptible. As an example, displays with pixel sizes of ~1 μm are particularly advantageous in this context.

[0045] Active global brightness control of variable wavelength LEDs

[0046] Another method to provide global brightness control for variable wavelength LEDs is to use liquid crystals for active dimming. Since an approximate response time of about ~100 ms is acceptable for global dimming applications, a ~1 mm nematic liquid crystal (NLC) with orthogonal polarizers can be added near the display to provide variable dimming levels.

[0047] The optical throughput of an LC cell (i.e., its dimming ratio) can be controlled in a simple way, for example, by appropriately setting the applied voltage. However, due to the net transmittance of the polarizer pair, the use of crossed polarizers in NLC cells will result in a significant reduction in display brightness, which is expected to be approximately 40%.

[0048] An alternative approach would be to use liquid crystal materials configured to scatter light, such as guest-host mode LC cells. Because this brightness control uses scattering rather than polarization control, there is no need to add orthogonal polarizers, and a much higher net transmittance can be achieved. The transmission of such scattering devices can be modulated by UV light or by voltage. As an example, the transmittance at a reasonable driving voltage can be approximately 70%, a significant improvement over NLC cells with polarizers.

[0049] Since scattered light is essentially a waste of energy, active global dimming using a liquid crystal layer can be combined with and supplemented by one of the other techniques described above in conjunction with global dimming control. For example, in one embodiment, 6-bit liquid crystal dimming can be combined with 2-bit grayscale dimming.

Claims

1. A method for controlling image reproduction on a color display having a pixel array, wherein, Each pixel includes multiple light-emitting diodes, and the method includes: Receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color brightness data of each pixel, the brightness data further including global dimming data of the pixel array; Based on this global dimming data, the global brightness of the pixel array is controlled by modulating the current value of each light-emitting diode applied to each pixel of the pixel array to one of a plurality of current value levels; and The color luminance data of each pixel is processed using one of a plurality of lookup tables to generate grayscale data of each of the plurality of primary colors in a color space for each pixel, wherein the lookup table is selected based on the current value to be applied to each light-emitting diode.

2. The method of claim 1, further comprising controlling the brightness of each light-emitting diode in each pixel of the pixel array by driving each light-emitting diode with pulse-width modulated current based on the grayscale data of each of the plurality of primary colors in the color space of each pixel.

3. The method as described in claim 1 or 2, wherein, The plurality of lookup tables includes fewer lookup tables than the number of current value levels, and the processing of the color luminance data of each pixel to produce grayscale data of each of the plurality of color space primary colors of each pixel further includes interpolation between two or more of the lookup tables.

4. The method as described in claim 1 or 2, wherein, The multiple lookup tables include lookup tables for each of the multiple current value levels.

5. The method according to any one of claims 1 to 4, wherein, These multiple lookup tables are multiple 3D lookup tables.

6. The method according to any one of claims 1 to 4, wherein, Each lookup table further includes a sub-lookup table for each of the plurality of color space primary colors, and wherein the relevant sub-lookup table is further selected based on the color space primary color associated with a given light-emitting diode.

7. An apparatus for controlling image reproduction on a color display having a pixel array, wherein each pixel includes a plurality of light-emitting diodes, the apparatus comprising: The input terminal is configured to receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color brightness data of each pixel, and the brightness data further including global dimming data of the pixel array; as well as A processor configured to control the global brightness of a pixel array based on the global dimming data by modulating the current value of each light-emitting diode of each pixel in the pixel array to one of a plurality of current value levels. The processor is further configured to process the color luminance data of each pixel using one of a plurality of lookup tables to generate grayscale data of each pixel in a plurality of color space primary colors, wherein the lookup table is selected based on the current value to be applied to each light-emitting diode.

8. The device as claimed in claim 7, wherein, The processor is configured to control the brightness of each light-emitting diode in each pixel of the pixel array by driving each light-emitting diode with pulse-width modulated current based on the grayscale data of each pixel in one of the multiple primary colors of the color space.

9. The device as claimed in claim 7 or 8, wherein, The plurality of lookup tables includes fewer lookup tables than the number of current value levels, and the processing of the color luminance data of each pixel to produce grayscale data of each of the plurality of color space primary colors of each pixel further includes interpolation between two or more lookup tables.

10. The device as claimed in claim 7 or 8, wherein, The multiple lookup tables include lookup tables for each of the multiple current value levels.

11. The device as claimed in any one of claims 7 to 10, wherein, These multiple lookup tables are multiple 3D lookup tables.

12. The device as claimed in any one of claims 7 to 10, wherein, Each lookup table further includes a sub-lookup table for each of the plurality of color space primary colors, and the processor is configured to select the relevant sub-lookup table based on the color space primary color associated with a given light-emitting diode.

13. A method for controlling image reproduction on a color display having a pixel array, wherein, Each pixel includes at least one light-emitting diode, and the method includes: Receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color brightness data of each pixel, the brightness data further including global dimming data of the pixel array; Process the color brightness data of each pixel to generate grayscale data of each of the multiple primary colors in the color space for each pixel; Determine a positive integer value n based on this global dimming data; and For each primary color in a color space, the brightness of each pixel in the pixel array is controlled as follows: Repeatedly loading and outputting the grayscale data of the primary colors of the color space corresponding to multiple rows of the pixel array for display, thereby progressively activating n rows of the pixel array to simultaneously output the grayscale data of the primary colors of the color space; and Further, the grayscale data of the primary color of the color space in any remaining row of the pixel array is repeatedly loaded and output for display, such that for the primary color of the color space, no more than n rows are started to output grayscale data simultaneously, and each row is started for the same duration.

14. The method of claim 13, further comprising controlling the brightness of each light-emitting diode of the pixel array by using pulse width modulation to drive each light-emitting diode based on the grayscale data of each of the plurality of primary colors in the color space of each pixel.

15. The method of claim 14, wherein, Each of these LEDs is driven by pulse-width modulated current.

16. The method according to any one of claims 13 to 15, wherein, Each pixel includes multiple light-emitting diodes, which are associated with the multiple primary colors of the color space.

17. The method according to any one of claims 13 to 15, wherein, Each pixel includes a light-emitting diode (LED) having a peak emission wavelength that depends on the drive current, such that the LED can reproduce light with the peak wavelength from two or more of the primary colors of the multiple color space.

18. The method of claim 17, wherein, The light-emitting diode is configured to emit light sequentially in two or more of the primary colors of the plurality of color spaces during each sub-frame.

19. An apparatus for controlling image reproduction on a color display having a pixel array, wherein each pixel includes at least one light-emitting diode, the apparatus comprising: The input terminal is configured to receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color and brightness data of each pixel, and the brightness data further including global dimming data of the pixel array; as well as A processor configured to process the color luminance data of each pixel to generate grayscale data of each of the multiple color space primary colors of each pixel. The processor is further configured to determine a positive integer value n based on the global dimming data; and The processor is further configured to control the brightness of each pixel in the pixel array for each primary color of the color space through the following steps: Repeatedly loading and outputting the grayscale data of the primary colors of the color space corresponding to multiple rows of the pixel array for display, thereby gradually activating n rows of the pixel array to simultaneously output the grayscale data of the primary colors of the color space; as well as Further, the grayscale data of the primary color of the color space in any remaining row of the pixel array is repeatedly loaded and output for display, such that for the primary color of the color space, no more than n rows are started to output grayscale data simultaneously, and each row is started for the same duration.

20. The device as claimed in claim 19, wherein, The processor is configured to control the brightness of each LED in the pixel array by using pulse width modulation to drive each LED based on the grayscale data of each of the multiple primary colors in the color space of each pixel.

21. The device as claimed in claim 20, wherein, Each of these LEDs is driven by pulse-width modulated current.

22. The device as claimed in any one of claims 19 to 21, wherein, Each pixel includes multiple light-emitting diodes, which are associated with the multiple primary colors of the color space.

23. The device as claimed in any one of claims 19 to 21, wherein, Each pixel includes a light-emitting diode (LED) having a peak emission wavelength that depends on the drive current, such that the LED can reproduce light with the peak wavelength from two or more of the primary colors of the multiple color space.

24. The device as claimed in claim 23, wherein, The light-emitting diode is configured to emit light sequentially in two or more of the primary colors of the plurality of color spaces during each sub-frame.

25. A method for controlling image reproduction on a color display having a pixel array, wherein, Each pixel includes at least one light-emitting diode, and the method includes: Receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color brightness data of each pixel, the brightness data further including global dimming data of the pixel array; Spatial dithering is used to process the color luminance data of each pixel to generate grayscale data for each of the multiple primary colors in the color space for each pixel; and Based on this global dimming data, the global brightness of the pixel array is controlled by using pulse width modulation to drive individual light-emitting diodes.

26. The method of claim 25, wherein, Each of these LEDs is driven by pulse-width modulated current.

27. The method of claim 25 or 26, wherein, Using spatial dithering to process the color brightness data of each pixel includes selecting individual dithering patterns for each image frame.

28. The method according to any one of claims 25 to 27, wherein, Each pixel includes multiple light-emitting diodes, which are associated with the multiple primary colors of the color space.

29. The method according to any one of claims 25 to 27, wherein, Each pixel includes a light-emitting diode (LED) having a peak emission wavelength that depends on the drive current, such that the LED can reproduce light with the peak wavelength from two or more of the primary colors of the multiple color space.

30. The method of claim 29, wherein, The light-emitting diode is configured to emit light sequentially in two or more of the primary colors of the plurality of color spaces during each sub-frame.

31. An apparatus for controlling image reproduction on a color display having a pixel array, wherein each pixel includes at least one light-emitting diode, the apparatus comprising: The input terminal is configured to receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color brightness data of each pixel, and the brightness data further including global dimming data of the pixel array; as well as The processor is configured to process the color brightness data of each pixel using spatial dithering to generate grayscale data of each of the multiple color space primary colors of each pixel; and based on the global dimming data, to control the global brightness of the pixel array by driving individual light-emitting diodes using pulse width modulation.

32. The device as claimed in claim 31, wherein, Each of these LEDs is driven by pulse-width modulated current.

33. The device as claimed in claim 31 or 32, wherein, Using spatial dithering to process the color brightness data of each pixel includes selecting individual dithering patterns for each image frame.

34. The device as claimed in any one of claims 31 to 33, wherein, Each pixel includes multiple light-emitting diodes, which are associated with the multiple primary colors of the color space.

35. The device as claimed in any one of claims 31 to 33, wherein, Each pixel includes a light-emitting diode (LED) having a peak emission wavelength that depends on the drive current, such that the LED can reproduce light with the peak wavelength from two or more of the primary colors of the multiple color space.

36. The device as claimed in claim 35, wherein, The light-emitting diode is configured to emit light sequentially in two or more of the primary colors of the plurality of color spaces during each sub-frame.

37. A method for controlling image reproduction on a color display having a pixel array, wherein, Each pixel includes at least one light-emitting diode and a liquid crystal cell positioned in front of the pixel array. The method includes: Receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color brightness data of each pixel, the brightness data further including global dimming data of the pixel array; Process the color luminance data of each pixel to generate grayscale data for each of the multiple primary colors in the color space for each pixel; and The optical transmission characteristics of the liquid crystal cell are controlled to control the overall brightness of the color display.

38. The method of claim 37, wherein, The liquid crystal cell includes a nematic liquid crystal layer between multiple orthogonal polarizers, and the optical transmission characteristics of the liquid crystal cell are controlled by an applied electric or magnetic field.

39. The method of claim 37, wherein, The liquid crystal cell is configured to scatter light incident on it.

40. The method of claim 39, wherein, The liquid crystal cell is configured in a guest-host mode.

41. The method of claim 39 or 40, wherein, The liquid crystal cell includes a polymer-dispersed liquid crystal layer, and the optical transmission characteristics of the liquid crystal cell are controlled by one or more of an applied electric field, an applied magnetic field, and / or incident ultraviolet light.

42. The method of any one of claims 37 to 41, further comprising controlling the brightness of each light-emitting diode of the pixel array by driving each light-emitting diode using pulse width modulation based on the grayscale data of each of the plurality of primary colors in the color space of each pixel.

43. The method of claim 42, wherein, Each of these LEDs is driven by pulse-width modulated current.

44. The method according to any one of claims 37 to 43, wherein, Each pixel includes multiple light-emitting diodes, which are associated with the multiple primary colors of the color space.

45. The method according to any one of claims 37 to 43, wherein, Each pixel includes a light-emitting diode (LED) having a peak emission wavelength that depends on the drive current, such that the LED can reproduce light with the peak wavelength from two or more of the primary colors of the multiple color space.

46. ​​The method of claim 45, wherein, The light-emitting diode is configured to emit light sequentially in two or more of the primary colors of the plurality of color spaces during each sub-frame.

47. The method of any one of claims 42 to 46, further comprising controlling the global brightness of the color display by controlling the pulse width modulation of each light-emitting diode of the pixel array based on the global dimming data.

48. An apparatus for controlling image reproduction on a color display having a pixel array, wherein each pixel includes at least one light-emitting diode, the apparatus comprising: The input terminal is configured to receive pixel data corresponding to an image to be displayed by the pixel array, the pixel data including color brightness data of each pixel, and the brightness data further including global dimming data of the pixel array; A processor configured to process the color luminance data of each pixel to generate grayscale data of each of the multiple color space primary colors of each pixel. as well as A liquid crystal cell, positioned in front of the pixel array and configured to control the global brightness of the color display by altering the optical transmission characteristics of the liquid crystal cell.

49. The device as claimed in claim 48, wherein, The liquid crystal cell includes a nematic liquid crystal layer between multiple orthogonal polarizers, and the optical transmission characteristics of the liquid crystal cell are controlled by an applied electric or magnetic field.

50. The device as claimed in claim 48, wherein, The liquid crystal cell is configured to scatter light incident on it.

51. The device as claimed in claim 50, wherein, The liquid crystal cell is configured in a guest-host mode.

52. The device as claimed in claim 50 or 51, wherein, The liquid crystal cell includes a polymer-dispersed liquid crystal layer, and the optical transmission characteristics of the liquid crystal cell are controlled by one or more of an applied electric field, an applied magnetic field, and / or incident ultraviolet light.

53. The device as claimed in any one of claims 48 to 52, wherein, The processor is configured to control the brightness of each LED in the pixel array by using pulse width modulation to drive each LED based on the grayscale data of each of the multiple primary colors in the color space of each pixel.

54. The device as claimed in claim 53, wherein, Each of these LEDs is driven by pulse-width modulated current.

55. The device as claimed in any one of claims 48 to 54, wherein, Each pixel includes multiple light-emitting diodes, which are associated with the multiple primary colors of the color space.

56. The device as claimed in any one of claims 48 to 54, wherein, Each pixel includes a light-emitting diode (LED) having a peak emission wavelength that depends on the drive current, such that the LED can reproduce light with the peak wavelength from two or more of the primary colors of the multiple color space.

57. The device as claimed in claim 56, wherein, The light-emitting diode is configured to emit light sequentially in two or more of the primary colors of the plurality of color spaces during each sub-frame.

58. The device as claimed in any one of claims 53 to 57, wherein, The processor is further configured to control the global brightness of the color display by controlling the pulse width modulation of each light-emitting diode in the pixel array based on the global dimming data.

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