KR102222725B1 - Method for reducing simultaneous contrast error - Google Patents

Abstract

A display panel having subpixels having respective colors to be displayed, and individually addressable to supply light to the subpixels of the display panel and including light emitters having respective colors, the display panel A display system having a backlight for receiving image data corresponding to an image displayed on, in an image display method for displaying an image, transmitted from the image data by each of the subpixels for displaying the image. Determining subpixel color values corresponding to color values, determining backlight values corresponding to brightness of the light emitters for displaying the image, from the image data, saturated yellow color of the image data And determining a portion of the subpixel color values and portions of the backlight values that entirely correspond to any one of yellow close to saturation. The backlight values are adjusted to increase the amount of yellow light emitted by the light emitters of the backlight. Adjusting and adjusting the color values to reduce the amount of yellow light transmitted by the subpixels of the display panel

Description

Image display method to eliminate simultaneous contrast error {METHOD FOR REDUCING SIMULTANEOUS CONTRAST ERROR}

The present invention relates to a method of displaying an image by removing a simultaneous contrast (color contrast) error in a display system.

A display system having a light source called a backlight is an active light control device and provides an image to a user by absorbing or passing optical energy generated from the light source. A liquid crystal display (LCD) device having a backlight is a kind of display system. The optical energy generated from the light source is active light and generates an image displayed on the display panel of the LCD device by the user. A display system using a color filter to display a color image typically has a narrow band color filter. The narrow band color filter generates color by extracting light energy from light generated from the light source. The color filter is disposed on the display panel, and has sub-pixel layouts of various types as shown in FIGS. 3 and 6-9 of the present invention. In general, only 4-10% of the light generated from the backlight light source appears as an image displayed to the user, resulting in lower luminance. In LCD devices, a thin film transistor (TFT) array and a color filter substrate are the biggest causes of lowering luminance.

A light emitting diode (LED) array is used as a light source of a backlight display system. About the backlight unit for an LCD device including a plurality of LED chips or a plurality of lamps for realizing red (R), green (G), and blue (B) colors BACKLIGHT UNIT IN LIQUID CRYSTAL DISPLAY ) Is disclosed in U.S. Patent No. 6,923,548. U.S. Patent No. 6,923,548 discloses a backlight having a high luminance characteristic and a thin thickness. A backlight control device for a transmissive or transflective liquid crystal display device using an LED as a backlight is disclosed in U.S. Patent No. 7,002,547 entitled BACKLIGHT CONTROL DEVICE FOR LIQUID CRYSTAL DISPLAY. The backlight control device includes an LED driving circuit and a current control device. The LED driving circuit is connected to the power supply circuit to drive the LED. The current control device senses the luminance around the liquid crystal display and controls the current for driving the LED. Hideyo Ohtsuki et al. published a paper titled 18.1-inch XGA TFT-LCD with wide color reproduction using high power led-backlighting using a 18.1 inch high-power LED backlight. Was presented at the Society for Information Display International Symposium in 2002. The paper discloses an XGA TFT-LCD module using an LED backlight unit. Ohtsuki et al. disclosed that in a side edge type backlight, two LED lines are arranged above and below the side edge on a light pipe. The light emitted from the red, green, and blue LEDs is mixed with each other and is incident into the light pipe. The luminance of the red, green, and blue LEDs may be independently darkened by a control circuit. Ohtsuki et al. stated that the color filter of the LCD panel well expresses high color saturation.

With respect to a backlight for a liquid crystal display device having a first LED array providing light of a first chromaticity and a second LED array providing light of a second chromaticity, an LED-based LCD backlight having an extended color space It is disclosed in U.S. Patent 6,608,614 entitled (LED-based LCD backlight with extended color space). The coupling member combines the light from the first LED array and the light from the second LED array and provides it to the liquid crystal display device. A control system is operably connected to the second LED array. The control unit adjusts the luminance of at least one LED in the second LED array to adjust the chromaticity of the combined light.

A U.S. patent publication, called High Dynamic Range Display Devices, with respect to a display device having a screen that is illuminated by light generated from a light source comprising a light control unit and an array of controllable luminous bodies. It is disclosed in US 2005/0162737 (hereinafter referred to as the 737 patent). The controllable light emitters and elements of the light control unit may control the intensity of light emitted from corresponding regions of the screen. FIG. 15 shows a display device 60 comprising a diffusion layer 22 and having a rear-projection screen 53 illuminated by an array 50 of LEDs 52. The brightness of each LED 52 is controlled by the control unit 39. The screen 53 includes a light control unit 20. The rear surface of the light control unit 20 is illuminated by the LED array 50. 14 shows a schematic front view of a display device 60 in which pixels 42 of the light control unit 20 correspond to each LED 52. Each of the adjustment elements 42 includes a plurality of colored sub-pixels. The 737 patent discloses that the LEDs 52 can be arranged in a suitable manner and can be arranged in rectangular and regular hexagonal arrays. The diffusion plate 22A is combined with the light emission characteristics of the LED 52 so that the light emitted from the LED 52 from the rear surface of the light control unit 20 has various intensities. The 737 patent discloses that the light control unit 20 may be a monochrome light control unit or a high-resolution color light control unit. The light control unit 20 may be an LCD array. The 737 patent discloses that the display device 60 may be in the form of a thin film. For example, the thickness of the display device 60 may be 10 cm or less.

Accordingly, the technical problem of the present invention is conceived in this respect, and an object of the present invention is to provide an image display method with improved image quality.

An image display method according to an exemplary embodiment for realizing the object of the present invention includes a display panel having subpixels having respective colors to be displayed, and individual addresses to supply light to the subpixels of the display panel ( Individually addressable) and including light emitters having respective colors, a display system including a backlight for receiving image data corresponding to an image displayed on the display panel, the display system comprising: Determining subpixel color values corresponding to color values transmitted by each of the subpixels for displaying the image from the image data, from the image data, the luminance of the light emitters for displaying the image ( determining backlight values corresponding to brightness), determining a part of the subpixel color values and a part of the backlight values entirely corresponding to any one of saturated yellow and near-saturated yellow of the image data, the Adjusting the backlight values to increase the amount of yellow light emitted by the light emitters of the backlight, and adjusting the color values to decrease the amount of yellow light transmitted by the subpixels of the display panel do.

In an embodiment of the present invention, the step of displaying the image using the adjusted backlight values and the adjusted color values may be further included.

In an embodiment of the present invention, the amount of yellow light added by adjusting the backlight values may be at least close to the amount of yellow light reduced by adjusting the color values.

In an embodiment of the present invention, the adjusting of the backlight values includes increasing the amount of red light emitted by red light emitters among the light emitters of the backlight, and a green light emitter among the light emitters of the backlight. It may include increasing the amount of green light emitted by the field.

In an embodiment of the present invention, the adjusting of the color values includes reducing the amount of red light transmitted by the red subpixels of the subpixels of the display panel, and the subpixels of the display panel. It may include reducing the amount of green light transmitted by the green subpixels.

In an embodiment of the present invention, adjusting the backlight values may include increasing the amount of yellow light to increase the amount of yellow light transmitted through the white sub-pixels of the sub-pixels of the display panel. have.

In an embodiment of the present invention, the light emitters may include multi-primary color light emitters.

In one embodiment of the present invention, the light emitters may include a red light emitter, a green light emitter, a blue light emitter, and a white light emitter.

A method for removing a simultaneous contrast error according to an embodiment for realizing another object of the present invention includes a display panel having subpixels and white subpixels having respective colors to be displayed, and the subpixels of the display panel. In a display system comprising a backlight for receiving image data corresponding to an image displayed on the display panel, including light emitters that are individually addressable and have respective colors to supply light to the fields, the display system comprising: A method for removing a contrast error, the method comprising: detecting one of a region having a saturated color and a region having a color close to saturation in the image, the amount of the color transmitted by the white subpixels of the display panel Increasing the amount of the color emitted by the light emitters of the backlight to increase the display panel, to compensate for the increased amount of the color transmitted by the white subpixels of the display panel And reducing the amount of the color transmitted by the subpixels.

In an embodiment of the present invention, after the increasing and decreasing steps, displaying the image may be further included.

In an embodiment of the present invention, the amount of the color added by the increasing step may be at least close to the amount of the color reduced by the reducing step.

In an embodiment of the present invention, the color may be yellow.

In an embodiment of the present invention, the increasing step includes increasing the amount of red light emitted by red light emitters among the illuminants of the backlight, and green illuminants among the illuminants of the backlight. It may include increasing the amount of green light emitted.

In an embodiment of the present invention, the reducing step includes reducing the amount of red light transmitted by the red subpixels of the subpixels of the display panel and the green subpixels of the display panel. It may include reducing the amount of green light transmitted by the pixels.

In an embodiment of the present invention, the light emitters may include multi-primary color light emitters.

In one embodiment of the present invention, the luminous bodies may include a red luminous body, a green luminous body, a blue luminous body, and a white luminous body.

According to such an image display method, an array of luminous bodies such as light emitting diodes (LEDs) is used as a backlight for a display system having subpixels, and thus can be filtered to have a higher color purity in image display than in the prior art. . However, in certain types of display panels (eg, liquid crystal display devices), the contrast ratio is limited, and thus bleed of color may occur compared to the off state of the sub-pixels. In addition, since the color filter itself does not have a high color purity, it is possible to unnecessarily transmit a part of colors generated by other color light-emitting bodies. In the display system of the present invention, individual luminous bodies arranged in the backlight array are independently addressed, and it is possible to more precisely control the color of the backlight. That is, the individual light emitters can be independently controlled to independently control the color of the backlight. The ability to independently control the color of the backlight increases the degree of freedom by increasing the color purity of the display device and an active driving area. In the case of sub-pixel rendering in sub-pixels of the display panel by optimizing the overall or local spread of luminance information of light emitted from the backlight array and having a constant color temperature Increases the efficiency of sub-pixel rendering.

Accordingly, by selecting a color value of the backlight to display an image, the image quality of the display device is improved, color reproducibility is increased, power consumption is reduced, luminance is improved, and simultaneous contrast error is reduced.

1A is a block diagram showing some components of a first temporary example of a multi-primary display system having a first backlight array having a multi-colored light emitter.
FIG. 1B is a block diagram illustrating an example of a block performing a peak down sampling function in the embodiment shown in FIG. 1A.
2A is a block diagram showing a part of a second multi-primary color display system including a second backlight array having a multi-color light emitter.
FIG. 2B is a block diagram illustrating a block performing a peak down sampling function in the embodiment shown in FIG. 2A.
3 is a plan view illustrating eight repeated subpixels in a four-color display panel.
4 is a plan view showing a part of a backlight array having three color light emitters.
5 is a plan view showing a part of a backlight array having four color light emitters.
6 is a plan view illustrating a part of a four-color display panel having six repeated subpixels.
7 is a plan view illustrating a part of a six-color display panel having six repeated subpixels.
8 is a plan view illustrating a part of a display panel having a group in which two square subpixels having two colors repeat.
9 is a plan view illustrating a portion of a display panel having a repeating group of 16 subpixels using rectangular subpixels having five colors.
10 is a block diagram showing a liquid crystal display system to which the backlight control technology and methods of the present invention are applied.
11 is a perspective view showing the use of input image data to determine a value of a light emitter in a backlight array.
12 is a cross-sectional view illustrating a backlight interpolation function for obtaining a low-resolution image by light generated from light emitters in a backlight array.
13 is a cross-sectional view illustrating an example of a display panel including a repeating group of multi-primary color sub-pixels having white sub-pixels and a method of using a white sub-pixel as a primary color by the backlight control techniques described in the present invention.
14 is a plan view showing a part of a display device having a rear-projection screen having a diffusion layer illuminated by an LED array in the prior art.
FIG. 15 is an organizational diagram showing controllable elements (pixels) in a light control member corresponding to each LED in the display device shown in FIG. 14.
16 shows an image color map smaller than a backlight gamut and a whiteite color space in CIE 1931 color coordinates.
FIG. 17 shows three virtual primary colors and a given color within the virtual primary color space in the backlight LED color coordinates shown in FIG. 16.
Fig. 18 is a block diagram showing a hybrid system having spatial and virtual main components controlling an LED backlight and an LCD device.
19A and 19B are timing diagrams showing two methods of reproducing a given color by the system shown in FIG. 18.
20A, 20B, and 20C are timing diagrams illustrating methods using virtual primary colors.
21A is a block diagram showing a virtual primary field sequential color system for sequentially reproducing a virtual primary color space.
21B is another embodiment showing the Calc virtual primary color module shown in FIG. 21A.
22 is a graph showing the bounding box module shown in FIG. 21A.
23 is a graph showing a multi-primary color LED color coordinate and overlapping XYZ primary colors representing an individual image color coordinate smaller than the multi-primary color LED color coordinate on a CIE 1931 color coordinate.
24 is a plan view illustrating a part of a display panel including 12 repeated subpixel groups having rectangular subpixels of five colors.
25 is a plan view illustrating an embodiment of a novel segmented backlight assembly used in a display device.
26 is a plan view showing a conventional backlight having a light guide plate and two light-emitting bodies.
FIG. 27 is a plan view illustrating an improved backlight than the backlight of FIG. 26.
28 is a plan view showing a conventional backlight having a light guide plate and four light-emitting bodies.
FIG. 29 is a plan view illustrating an improved backlight than the backlight of FIG. 28.
30 is a plan view showing another novel segmented backlight assembly.
31 is a cross-sectional view showing a light guide plate of a new segmented backlight assembly.
Fig. 32A is a block diagram showing a new segmented backlight combined with a black and white panel disposed on the front side.
Fig. 32B is a block diagram showing a new segmented backlight combined with a multi-primary color panel disposed on the front side.
33 is a block diagram illustrating a display system having a new segmented backlight to which a system and method for continuous control of a mixed virtual primary color space is applied.
34 is a two-dimensional graph defined by virtual primary colors and simplifying input pixels.
35 and 36 are two-dimensional graphs in which the exclusion gamut defined by virtual primary colors and improved by the present invention is simplified.

The present invention will be described in detail in the text, since various modifications can be made and various forms can be obtained. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals have been used for similar elements. Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component. The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "consist of" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of the presence or addition.

Unless otherwise defined, all terms used in the present invention, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not. The invention is defined by the appended claims.

In the following, components of the display system are first described, and a driving technology of the backlight array is described. Next, a process of visual recognition by the human eye by driving the backlight, a display of an image of a specific color, and a relationship between a layout of a specific sub-pixel on the display panel, and the like will be described.

The display system includes a display panel on which an image is displayed, and the display panel includes a color filter substrate in which color filters corresponding to individual colors are arranged. The color filters are arranged according to a repeated subpixel group or subpixel layout. The primary color refers to each color that appears in each repetitive subpixel group. When a repeating subpixel group is formed on the display panel in a predetermined matrix form, the display panel is expressed as having a repeating subpixel group. The display panel has substantially repeated subpixel groups. The reason for using the expression “substantially” is that there may be some changes in the repetitive shape of the sub-pixels in a part of the display panel, for example, at a corner or a side part. For example, the display panel has three primary colors in which red (R), green (G), and blue (B) colors are repeated in the vertical column of the color filter substrate, and the display panel is magenta, also referred to as magenta (Fig. 8). 801) may have two primary colors of a subpixel and a blue subpixel 808. A display system including sub-pixels having three or more primary colors is referred to as a multi-primary display system. The display panel may have white subpixels to form a display system of four primary colors of red (R), green (G), blue (B), and white (W).

In the detailed description of the present invention, a monochrome image includes not only an image composed of black, gray, and white, but also an image displayed by monochromatic light, for example, an image viewed in a darkroom lit by a red light.

The term emitter may refer to individual subpixels corresponding to a characteristic color, and the light emitter may refer to a light source disposed in a backlight array of a display system. The term backlight-controlled (BC) primary color or variable primary is created by one or more luminaries in an array of luminaries that function as backlights for a display system and passes through white subpixels. It means the color of one light.

Example 1 related to the display system

1A is a block diagram illustrating a display system 100 including a spatial light control panel 160 to display an image. The panel 160 is a display panel including repeated subpixel groups 162. The repeated subpixel group 162 may be a subpixel group illustrated in FIGS. 3, 6, 7, 8, and 9. 3 shows a repeating subpixel group 320 that can be used in the panel 160. The repeated subpixel group 320 includes a red subpixel 206, a green subpixel 308, a blue subpixel 310, and a white subpixel 304. The white subpixel 304 includes a subpixel without a color filter, a clear subpixel, and the like. The repeated subpixel group 320 may be modified in various forms. For example, US Patent 7,876,341 entitled “Subpixel layouts for high brightness displays and systems”, “Subpixel layouts and arrangements for high brightness displays” )”, the sub-pixels disclosed in US Patent No. 7,583,279, etc. may be included. For example, in the repeated subpixel group 620 of FIG. 6, two green subpixels 608 are disposed between a white subpixel 604 and a blue subpixel 610 within a grid pattern. In the drawing, a hatching line representing a subpixel layout representing a part of a display panel or repeated subpixel groups represents a color of a subpixel.

The technique of controlling the backlight of the display system may also be applied to a display system having subpixel groups having fewer or more colors than the RGBW subpixel groups of FIG. 3. For example, in FIG. 7, a red subpixel 706, a green subpixel 708, a large blue subpixel 710, a cyan subpixel 707, a magenta subpixel 709, and a yellow subpixel ( A portion 700 of a six-color display panel having a repeating subpixel group 701 consisting of 711 is shown. In the drawing, the cyan subpixel 707 is indicated by a hatched line having a thickness thinner than that of the blue subpixel. In FIG. 9, a subpixel group 902 in which 16 subpixels consisting of a red subpixel 906, a green subpixel 908, a blue subpixel 910, a cyan subpixel 912, and a white subpixel are repeated. A part of the five-color display panel having a is shown.

The technique of controlling the backlight of the display system can also be applied to a display system having a subpixel group having a smaller number or a larger number of primary colors than the illustrated one. For example, FIG. 8 shows a part 800 of a two-color display panel including a subpixel group 801 in which subpixels composed of magenta subpixels 809 and green subpixels 808 are repeated. . The display panel 160 of FIG. 1A may include a repeated subpixel group 801.

Referring again to FIG. 1A, the display system 100 includes an array 120 of light emitters 122 as a backlight of the panel 160. The array 120 is composed of light emitters 122 having different colors. The light emitters are addressed by electric signals driven completely independently for different colors of the array 120. The array of light-emitting bodies 120 includes a light-emitting diode (LED) or other light-emitting devices that can be independently addressed. For example, a second liquid crystal display, an organic light emitting display (OLED), a carbon nanotube field emission display (CNT), a plasma display panel (PDP) , Rear projection television (RPTV), Cathode Ray Tube (CRT), and various types of color flat panel display panels may be used.

4 and 5 are plan views showing a part of the layout of an array 120 of light emitters used as a backlight. 5 is a plan view showing a part of an offset (or hexagonal) array 500 of red (R) luminous bodies 506, green (G) luminous bodies 508 and blue (B) luminous bodies 510 to be. The illuminant array 500 is a backlight of a panel having various RGBW layouts, such as a backlight of an RGB display panel, a backlight of an RGBW display panel shown in FIG. 3 or 6, or a backlight of an RGBW display panel disclosed in US Patent 7,876,341 or US Patent 7,583,279. Can be applied as

4 shows a portion of a rectangular array 400 comprising a red illuminant 406, a green illuminant 408, a blue illuminant 410, and a cyan illuminant 412. Hereinafter, the rectangular array 400 is referred to as an RGBC light emitter. Turquoise is also known as emerald color. The illuminant array 400 may be used as a backlight of a display panel including an array consisting of a repeating RGBC subpixel group or an RGBCW subpixel group 902 shown in FIG. 9. The illuminant array 400 is suitable as a backlight of a display panel including illuminants having four colors and including a repeating RGBW subpixel group. When the pass band of the green subpixel includes both green and cyan emission wavelengths, the illuminant array 400 may change the green pixel to be cyan (or emerald).

The luminous body arrays 400 and 500 shown in FIGS. 4 and 5 include luminous bodies arranged in a rectangular or hexagonal shape, respectively. Techniques for using this arrangement for the backlight are described below. All of the various layouts can be applied to the backlight control technique described below. The correlation between the light emitters, colors in a displayed image, and layouts of subpixels of the display panel will be described below. Information on the resolution of the luminous body array (120 in Fig. 1) will be described later.

Referring again to FIG. 1A, the display system 100 has two data paths for accommodating RGB image data 102. The first RGB image path includes an input gamma (gamma or linearization) module 105, a color space mapping (GMA) member 140, a subpixel rendering (SPR) module 150, and an inverse gamma (inverse gamma) module. gamma) module 115 and generates output image data for displaying an image on the panel 160. In the various display systems described above, the GMA member 140 changes input color data of RGB primary colors into a target color space of multiple primary colors such as RGBW. The output of the GMA member includes image color values, luminance and identification elements in the RGBW color space. For information on the operation of the color space mapping function, refer to “Method and apparatus for converting from source color space to RGBW target color. US Patent 7,728,846 entitled “space)”, US Patent 7,893,944 entitled “Gamut mapping and subpixel rendering systems and methods”, and “selecting a white point for image display. It is disclosed in US Pat. No. 7,864,188 entitled “Systems and methods for selecting a white point for image displays”.

In the display system 100, the GMA member 140 generates a requantized image for display on the panel 160 by using the output function of the box 136 marked _{“X/X L”.} . The box 136 marked “X/X _L ”is generated by the backlight interpolation function 130 and displayed as RLGLBL as well as the input RGB from the input gamma operation 105. Accepts input RGB image values. The backlight interpolation block 130 and the X/X _L member 136 are described below. The GMA member 140 is applicable to the above-described color gamut mapping techniques, conventionally disclosed gamut mapping techniques, or color gamut mapping techniques to be developed in the future. In a display system that generates an image on a display panel having repeated RGBW subpixels, the GMA member 140 is used to convert RGB data into RGBW data.

According to the first data path of FIG. 1A, input image color values (eg, RGBWL) generated by the GMA member 140 and mapped to a color gamut are sub-pixel rendering (SPR) members ( 150). The operation of the SPR member 150 is US Patent No. 7,920,154 entitled “Subpixel rendering filters for hight brightness subpixel layouts”, and “multi-primary color subpixel rendering using conditional color filtering” (Multiprimary color subpixel rendering with metameric filtering)” is disclosed in US Patent No. 7,787,702. In Fig. 1A, an arrow pointing downward from the inside of the box shown at 150 indicates that the SPR member performs a down sampling function. When the SPR member serves as a downsampling function, the number of displayed color subpixels becomes smaller than the number color sampled from the GMA member. The output value (e.g., RGBW) from the SPR member 150 is output to an output gamma function 115, and the output gamma member 115 transmits an output image data value to the panel 160 To output and display.

Backlight control function

With continued reference to FIG. 1A, the RGB input data 102 of the display system 100 proceeds along the second data path. The second data path integrates the operation of the backlight array 120 of light emitters to be displayed as an output image. The second data path includes a peak function block 110. The peak function block 110 calculates a value of the temporary illuminant of the array 120. The backlight interpolation function 130 calculates a distribution of light having each color corresponding to each pixel on the illuminant array 120 by using values of the illuminant. The output of the backlight interpolation block 130 is indicated by RLGLBL in FIG. 1A. The output of the backlight interpolation block 130 is generated by filtering RGB input image data. The distribution of light from the illuminant array 120 is tailored to correspond to the RGB input image data. The members 110 and 130 will be described in detail below.

The peak function block 110 determines values of the illuminants of the array 120 by using the RGB input image data 102. As a simple example, the peak function block 110 may be Max(VPSF). Here, the value of V in the luminous body of a given color is the same as the maximum value of the color channel of the original input image in a local area affected by the point spread function (PSF) of the luminous body. The original input image is generated through gamma pre-conditioning in the input gamma module 105. The peak function block 110 may have a form of downsampling. Downsampling corresponds to a downward arrow in block 110 shown in FIG. 1A. The output value of down-sampling in a given illuminant is obtained by the peak value of the input image data within a region defined by adjacent illuminants having the same color.

11 is a diagram illustrating an interaction between a light emitter of the display system 100 and input image data. 11 shows a portion of an array 120 including illuminants 124 and 126. Reference numeral 103 denotes the optical input image data 102 of FIG. 1A on a diagram, and the input image data is processed by the input gamma member 105. The data 103 on the diagram is data of input color values that are overlaid on the array 120 of light emitters as input image data. The point intensity distribution function of the luminous body 124 represents the area 130 covered by the luminous body 124 and is defined by the chain lines and the chain lines 131. The point intensity distribution function of the illuminant 124 corresponds to the image portion 104 of the input image color data shown by the data 103 on the diagram. The light generated from the luminous body 124 has a luminance level sufficient to represent the light corresponding to the brightest input color data value in the image portion 104. The point diffusion distribution function of the illuminant 124 overlaps with the point diffusion distribution function of the other illuminant 126, which is shown as a portion where the two regions 130 and 132 defined by the dashed lines overlap. Some of the input image color values used to determine the value of the illuminant 124 are also used to determine the value of the other illuminant 126.

Table 1 shows what is called "dopeak" in a pseudo code that determines the value of one illuminant by using the maximum value of the input image region as an example of the peak function. That is, as for the peak function, the output display panel has a resolution of 8 times that of the backlight array, and the backlight array includes the same red, green, and blue light emitters arranged in a rectangle (or square).

function dopeak (x,y) --build backlight image
local r,g,b
local Rp,Gp,Bp=0,0,0
local i,j
for i=0, 15 do --find the peak value
for j=0,15 do
r,g,b=spr.fetch(“ingam”,x*8+1-4,y*8+j-4)
Rp = math.max(Rp,r)
Gp = math.max(Gp,g)
Bp = math.max(Bp,b)
end
end
spr.store(“led”,x,y,Rp,Gp,Bp)
end

Those of ordinary skill in the art may use more advanced sampling methods using a sync or window sync function or other techniques. All possible sampling functions can be used in the backlight control technique disclosed herein.

In Table 1, the spr.fetch function means fetching data from a previous step or arriving at a current step. For example, data may be imported from the input gamma module (105 in FIG. 1). The Spr.store function means storing data for the next step or sending data to the next step. For example, it may refer to the backlight array values 112 stored in the LED array 122. The virtual code in Table 1 can bring input values in a random access mode. Through the random extraction mode, each value can be retrieved several times, and the output values can be stored in order. This process can also be implemented through software. In hardware, fewer data are used by processing in the order of the inputs, and the input boxes are stored in the input line buffer until enough numbers are collected to calculate the output value. As another embodiment, input values may be sequentially processed using a small number of gates, intermediate results may be immediately output, and then stored in output line buffers until completion.

The output peak function 110 outputs a value indicating the luminance level of the illuminant in each illuminant of the array 120. The luminous body values are input to a backlight array controller (not shown) for subsequent light emission of the backlight array 120 when the output image is displayed on the panel 160.

12 is a diagram showing an interaction between a light emitter and output image data in the display system 100. The backlight interpolation block 130 uses the value of each luminous body 124 of the backlight array 120 in the peak function block 110 to each output pixel 164 of the display panel 160 placed on the luminous body 124. Calculate the distribution of light with each corresponding color. The distribution is calculated by interpolating the values of the luminous bodies by the peak function block 110 in consideration of the point distribution function (PSF) of each of the light bodies 124 of the array 120, the presence of the diffusion plate 136, and the like. It becomes. The interpolation action is called an “up sampling” function, and is indicated by an upward arrow. In this case, up-sampling having various types of embodiments may be possible. The function is obtained by multiplying the summation by the point sample contribution of the PSF values of the local illuminant by the value calculated by the downsampling peak function block 110.

Table 2 is a virtual code representing the backlight interpolation function called “dointerp”. The function fetches from a memory called “ledbuf” (LED buffer), and stores the output color value “fuzbuf” in the memory area. A function called "dointerp" is called for each input pixel and calculates the effect of all the backlight point intensity distribution functions around it to generate a color value shown in a predetermined input pixel (local pixel). The “dointerp” function uses the point intensity diffusion function of each luminous body, assuming that each pixel is affected by the four luminous bodies around it.

function dointerp(x,y) --build the effective backlight image
local xb,yb = math.floor(x/8),math.floor(y/8) --position of a nearby
- backlight
local xd,yd = spr.band(x,7),spr.band(y,7) --distance to a nearby LED center
local r,g,b --color of the backlight centers
local rs,gs,bs=0,0,0 --sum of the overlapping backlight point spread functions
local psf --point spread function for current pixel and LED
r,g,b = spr.fetch(ledbuf,xb-1,yb-1) --get LED center color
psf = math.floor(spread[xd]*spread[yd]/4096) --calculate point spread
--function here
rs = rs + r*psf --sum upper left LED
gs = gs + g*psf
bs = bs + b*psf
r,g,b = spr.fetch(ledbuf,xb,yb-1) --color of upper right LED
psf = math.floor(spread[7-xd]*spread[yd]/4096) --PSF for this led and pixel
rs = rs + r*psf --sum upper left LED
gs = gs + g*psf
bs = bs + b*psf
r,g,b = spr.fetch(ledbuf,xb-1,yb) --color of lower left LED
psf = math.floor(spread[xd]*spread[7-yd]/4096) --PSF for this led and pixel
rs = rs + r*psf --sum upper left LED
gs = gs + g*psf
bs = bs + b*psf
r,g,b = spr.fetch(ledbuf,xb,yb) --color of lower right LED
psf = math.floor(spread[7-xd]*spread[7-yd]/4096) --PSF for this led and pixel
rs = rs + r*psf --sum upper left LED
gs = gs + g*psf
bs = bs + b*psf
rs = math.floor(rs/4096) --sum was 12bit precision (+2 for
- 4 LEDs)
gs = math.floor(gs/4096) --colapse them back to 8bits
bs = math.floor(bs/4096)
spr.store(fuzbuf,x,y,rs,gs,bs); --and save in output buffer
end

The “down sampling” of the peak function block 110 and the “up sampling” of the backlight interpolation block 130 are combined to maintain the original resolution of the input image in terms of sample count and image size. _A set of output image values represented by L G _L B _{L can be obtained.} In this case, the output image values have a low spatial frequency. _{The set of output image values represented by R L} G _L B _L in FIG. 1A is a filtered value of RGB input image data, which is an approximation of the distribution of the illuminant array 120. The data (ie, a set of output image values _{) is input to the X/X L} member 136 to be described below. In this case, some of the images may have a region having a uniform (or the same) color value. Information on the location of a uniformly colored region in the image may reduce a computational load of the GMA member 140 by retaining/reusing values for the region.

Before being input to the GMA member 140, the input image RGB data is determined to determine the relationship between the luminance of each input RGB value passing through the input gamma member 105 and the actual value of the RGB values that are actually possible in a given pixel from the backlight array 120. It is primarily corrected by the backlight interpolation block 130 in consideration. For example, it may be primarily corrected by the backlight interpolation block 130 to become an RLGLBL data value. The modification may be performed by the X/X _L member 136 in consideration of the X/X _{L ratio.} At this time, X is the input value of R, G, or B, and X _L represents the backlight luminance value in the R _L , G _L or B _{L pixels.} Accordingly, the process of mapping RGB to the RGBW color region has R/R _L , G/G _L or B/B _L as input values. Those skilled in the art may use the _{off-the-shelf GMA function as the X/X L} member 136 as a light contribution of the illuminant of the backlight array 120 without any modification.

The backlight control method and technology of the present invention may be combined with a known frame, field blanking technology, and row scanning technology, and is called "jutter" that may occur in some sections of an image. It can reduce or eliminate motion artifacts.

How to control color out of color space using extended peak function

When the output value of the predetermined illuminant is a regional peak value of the input image data (for example, data calculated within a region surrounded by adjacent illuminants in a specific color), the peak function block 110 is used to When is set to the regional peak value, the image color saturated relatively brightly compared to the regional peak value is displayed. In this way, an image color that is saturated relatively brightly compared to the local peak value is defined as “out-of-gamut” (out of color space; OOG). In this case, a function of setting a backlight luminous body to display a higher luminance image color is required.

The peak function makes it possible to accommodate an image color out of a color space when a value obtained from a simple local peak function and a value of a set illuminant are different from each other. An extended peak function block 1100 is shown in the block diagram of FIG. 1B. As another embodiment, the extended peak function block 1100 of FIG. 1B may replace the peak function block 110 of FIG. 1A. The peak irradiation block 110 performs the same function as the peak function block 110 of FIG. 1A, and irradiates the linear input image RGB value of each pixel to determine the peak of the illuminant within the point intensity distribution function region corresponding to each illuminant. Find the value.

In order to determine whether some of the input image colors are out of the color space by the illuminant values, a color space mapping function is performed using the output illuminant value generated by the peak irradiation block 110. Accordingly, in order to perform a function of checking and accommodating whether an input color value is out of a color space by using a local peak function, the extended peak function block 1100 performs various functions described with respect to the display system 100. It can be included in duplicate.

Continuing with reference to FIG. 1B, the luminous body value output from the peak irradiation block 110 is input to the backlight interpolation block 130 to generate _{R L} G _L B _{L values.} The input image RGB value and the R _L G _L B _L value are normalized by the block indicated by reference numeral 135. The normalized value is input to the color space mapping function RGB(W) GMA member 1150. However, the output W value and the output L value that are not generated by the normal RGBW GMA function are not required and are not input to the RGB(W) GMA member 1150. This is because the RGB(W) GMA member 1150 may have the possibility that only the RGB values deviate from the color space. RGB(W) The RGB value output from the GMA member 1150 is irradiated by the OOG peak irradiation block 1160 to determine a maximum value out of the color space within the point intensity distribution function region in which each luminous body is disposed. The maximum value out of the color space in the peak correction block 1160 is multiplied by the original luminous body value generated by the peak irradiation member 1110 to increase the value of the luminous body, thereby correcting so that the color out of the color space decreases. In this case, the peak correction block 1160 may be further multiplied by an appropriate scaling factor.

Example 2 related to the display system

2A is a block diagram illustrating a display system 200 including a spatial light control panel 260 to display an image according to a second exemplary embodiment of the present invention. The spatial light control panel 260 may be a liquid crystal display (LCD) panel. The panel 260 is a display panel having multiple primary color subpixels. Panel 260 has five colors of red-green-blue-blue-green-white (RGBCW). 9 shows a repeating subpixel group 902 that can be used in the panel 260. For example, the display system 200 includes an array of light emitters 220 used as backlights of the panel 260. The array 220 includes light emitters having different colors. The illuminants are addressed by electrical signals driven completely independently for different colors of the array 220. The array of light emitters 220 includes a light emitting diode (LED) or other light emitting devices that can be independently addressed. Examples of the light emitting devices may be applied to the display system shown in FIG. 2A as long as they can be independently addressed and controlled as listed in the description of FIG. 1.

In FIG. 2A, the array 220 includes light emitters having four colors of RGBC corresponding to the primary colors of the repeated subpixel group of the panel 260. The display system 200 includes light emitters having N saturated primary colors corresponding to the N saturated primary colors of the repeated subpixel group used in the display panel 260. The N saturated primary colors of the illuminant are denoted as "s.primary". At this time, the W primary color (white primary color) is regarded as an unsaturated primary color. In this case, when the display device does not include W as the primary color, the display device may be matched one-to-one with the saturated primary colors of the light emitters of the array 220. However, when white (W) is added as a primary color as disclosed in the present invention, it is possible to improve image quality and expand a dynamic region of a color space in an output image.

Input image data path

In the display system 200, input image RGB data is mapped into a color space by controlling a backlight array having N saturated primary colors and rendering subpixels. The input image RGB data is mapped into the color space, thereby generating an output color image within the color space of the display panel 260 having N primary colors. A gamma look-up table (LUT) for converting R*G*B* data input in a normal nonlinear version into linear data or gamma quantized (205) is used. The R*G*B* data input by the gamma lookup table 205 is transformed into a linear RGB value with a higher bit depth.

RGB data output from the input gamma member 205 is input to the GMA member 207 for the N saturated primary colors. The GMA member 207 for the N saturated primary colors maps RGB input image data to the color space of the N saturated primary colors of the backlight array 220. The GMA member 207 uses various methods of color space mapping the input RGB data into N saturated primary colors. For example, PCT application PCT/US 06/12766 entitled “Systems and methods for implementing low-cost gamut mapping algorithms” as the color space mapping method (hereinafter A method of converting a three-color input signal disclosed in "PCT 766" to a four-color signal may be used. By using the above method, the RGB input image data in the GMA member 207 can be converted into the four primary color spaces of the backlight array (220 in FIG. 2A). For example, the four primary colors may be used in an RGBC backlight array.

The GMA member 207 may use a technique of selecting a condition metamer. An example of a technique for selecting conditional color space is disclosed in US Patent Application No. 11/278,675 entitled “Systems and methods for implementing improved gamut mapping algorithms”. When four or more non-coincident primary colors are used in a multi-primary color display device, a plurality of primary color combinations corresponding to the same color value are possible. The conditional color (metamer) in a display device having subpixels is a combination of at least two color subpixels. When signals are applied to each group, the desired color is visually recognized in the human field of view by conditional color. When a predetermined color is changed to a different conditional color, the peak value may be decreased or have the same value in the color space of the N saturated primary colors output from the illuminant. That is, one or more light emitters are darkened to be optimized, so that an optimized requantization of an output image value and reduction in backlight power consumption can be obtained.

The output color signal of the GMA member 207 is processed by the peak function block 210 and output as a value corresponding to the luminous body of the array 220. In this case, the output color signal of the GMA member 207 may be specified in the color space of the N saturated primary colors of the light emitter in the backlight array 220. The peak function block 210 generates a low-resolution color image for the array 220, and the color image corresponds to the N saturated primary colors of the backlight array 220.

The low-resolution color image output by the peak function block 210 is also input to the backlight interpolation block 230 to calculate the color and luminance of the backlight at each input position. In another embodiment, the backlight interpolation block 230 may calculate a color and luminance corresponding to the position of each subpixel of the panel 260. Before being processed by the second gamut mapping operation (GMA, 240), the input image RGB values are mapped to N saturated primary colors of the backlight array 220 and output by the backlight interpolation block 230. The image with the lower resolution is normalized. In a backlight array having a luminous body of RGBC primary colors and a multi-primary color display system having RGBCW primary colors, a normalization member (normalization function) 235 calculates the ratio of RLGLBLCL values to RGBC input colors to effectively generate bright white in the backlight, Output to the color space mapping member 240. The normalization member 235 may perform a color space mapping function even when a color of an image applied to the display system 200 is out of the color space (off-the-self).

The second gamut mapping function (GMA) 240 converts the normalized input image data specified in the color space corresponding to the N primary colors of the array 120 to the primary color system of the display panel 260. Convert. For example, the second color space mapping member 240 may convert RGBC input data into an RGBCW multi-primary color system. The second color space mapping (GMA) member 240 calculates not only primary color values but also luminance (L) and provides them to the SPR member 250. The second color space mapping (GMA) member 240 is US Patent No. 7,920,154 entitled “Subpixel rendering filters for high brightness subpixel layouts”, “multi-primary colors using conditional color filtering. Techniques such as US Patent 7,787,702 entitled “Multiprimary color subpixel rendering with metameric filtering” and the RGBCW subpixel layout 902 of FIG. 9 may be used. In addition, various modifications such as more advanced types of filters and codes to be described below are possible. Image data output from the SPR member 250 is output to an inverse gamma lookup table (LUT) 215 to compensate for a nonlinear response of the display device.

The SPR member 250 performs various methods of subpixel rendering. Some subpixels may be quite far from other subpixels having the same color. For example, the following pixel arrangement is possible.

R W G W C W B W

C W B W R W G W

Here, there is a considerable distance between the two R subpixels. In the case of such an arrangement, not only the sharpness between the same colors is improved, but also the sharpness between the colors in the relationship of the conditional color is improved. For example, when the white subpixel is ignored, the repeating pattern of the pixels is as follows.

R G C B R

C B R G C

R G C B R

When a square surrounding three columns in the middle of the pattern is drawn, and a square area is resampled for subpixel rendering, the filter kernel is as follows.

1 2 1

2 4 2

1 2 1

Each coefficient is divided by 16*M. In this case, M is a constant used to maintain the color required to exchange green/blue to red/cyan or vice versa.

The sharpness filter that conditionally colors red/cyan to green/blue is as follows. That is, the following refers to a sharpness filter that converts energy from blue/green color to blue-green/red color.

-1 +2 -1

-2 +4 -2

-1 +2 -1

At this time, each coefficient is again divided by 16. The red subpixel R is in the center, and the pattern is repeated in a diagonal direction. The sharpness filters for the same color are as follows.

-2 0 0 0 -2

0 0 +8 0 0

-2 0 0 0 -2

At this time, each coefficient is again divided by 16. The area resample and sharpening filters for the same color are combined with each other to form a filter as follows.

-2 1 2 1 -2

0 2 12 2 0

-2 1 2 1 -2

At this time, each coefficient is again divided by 16. Here, the sharpening filter for the same color as the region resample may be used during the subpixel rendering period in each color plane. Subpixel rendering may be performed by the SPR member 250. In addition, a sharpness filter that conditionally colors red/blue-green into green/blue may adjust sub-pixels using a luma value. Briefly, in the conditional same color sharpness filter, the constant M may be set to 1, which is a constant corresponding to a case where color accuracy is partially sacrificed for image clarity and filter simplification. As another embodiment, by making M have an appropriate value, image clarity and filter simplification may be partially sacrificed for color accuracy.

In the case of combining area resampling, self-color sharpening, and metamer sharpening based on the luminance value of the pixel, the color is filtered in the RGBCW layout (209 in FIG. 9). By rendering the sub-pixels, an improved sub-pixel image can be obtained. The subpixel rendering image can be obtained through the following virtual code.

. combo = --combined area resample and self-color sharpening filter

{

xsize=5,ysize=3,

-32, 16, 32, 16, -32,

0, 32,192, 32, 0,

-32, 16, 32, 16, -32,

}

RCGBMS = --RC <-> GB metamer sharpening filter

{

xsize=3,ysize=3,

-16, 32, -16,

-32, 64, -32,

-16, 32, -16,

}

--routine to do the SPR filtering

--reads from buffer in string variable gmabuf

--writes to buffer named in string variable sprbuf function dospr(x,y)

local lft,rgt --values during SPR

local R,B,C,G,W,L = 0,1,2,3,4,5 --give names to the locations in the GMA buffer

local color = spr.bxor(spr.band(x,3),spr.band(y,1)*2) --color at this checkerboard position

local lft,wht, prev, next

local sharp = spr.sample(gmabuf,x,y,L,RCGBMS)

lft = spr.sample(gmabuf,x,y,color,combo)+sharp

wht = spr.fetch(gmabuf,x,y,W) --the whites are just completely sampled!

lft = math.floor(lft/256) --filters are times 256

lft = math.max(0,lft) --sharpening filters can cause overflow or underflow

wht = math.max(0,wht) --we've got to clamp it to the maximum range

lft = math.min(MAXCOL,lft)

wht = math.min(MAXCOL,wht) --may not be necessary on white...

spr.store(sprbuf,x,y,lft,wht)

end --function dospr

Operation of gamut mapping function

The color space mapping (GMA) member 207 maps the input RGB image data to a color space of saturated primary colors of the backlight array. For example, the color space mapping (GMA) member 207 converts RGB input image data into a backlight array (220 in FIG. 2A) using a four primary color space such as an RGBC backlight array. The disclosed technology or the like can be used. The second color space mapping (GMA) member (240 in Fig. 2A and 2160 in Fig. 2B) uses a technique similar to the color space mapping technique disclosed in PCT 766. However, this technique converts the four color signals RGBC generated by the color space mapping member 207 into RGBCW signals used in the display panel 260 as follows. For simplicity, in the following, an RGBC backlight array and an RGBCW display panel are applied. However, the technology of the present invention is not limited to this example, and can be applied to a backlight array having the same number of primary colors as the above example and a display panel having the same number of primary colors as the above example. For example, a backlight array of RGBC primary colors may be applied to a display panel of RGBCW primary colors, or a backlight array of primary colors of RGBY (Y is yellow, yellow) may be applied to a display panel of RGBYW primary colors. Also, it may be applied when the display panel further has one or n saturated primaries compared to the backlight array.

To develop the color space mapping (GMA) member 207, a 4x3 matrix is calculated from the luminosity and chromaticity of the RGBC backlight array. The matrix may convert RGBC values into values of the CIE XYZ color coordinate system. The matrix can be calculated by various known methods. The 4x3 matrix is represented by the following [Equation 1].

[Equation 1]

In a similar way, a 5x3 matrix that converts RGBCW values to values in the CIE XYZ color coordinate system can be calculated. The 5x3 matrix is represented by the following [Equation 2].

[Equation 2]

In a single color, the two equations are combined with each other and expressed as [Equation 3] below.

[Equation 3]

Of course, since none of the matrices in [Equation 3] are square matrices, the values of [Rw, Gw, Bw, Cw, Ww] cannot be directly derived from the values of [Rc, Gc, Bc, Cc]. However, the absence of a logical solution does not mean that such an equation cannot be solved, so there are many ways to obtain a reasonable approximation.

For example, a reasonable approximation solution can be obtained by the method disclosed in PCT 766. According to this method, the matrix can be converted into a square matrix. If you find a square matrix, you can find the solution. In [Equation 3], values of Cw corresponding to cyan and Ww corresponding to white are assumed to be constants, and are separated from the matrix (factored). For example, in a white sub-pixel, the value of Ww does not have a significant effect on the result even if it is assumed to be a constant in the matrix in view of the relationship between the luminance of the input value and the luminance of the output value. In a similar way, the Cw value can be calculated by setting it as the Cc value of the input value. Assuming the Ww value and Cw value as constants, [Equation 3] is changed as in [Equation 4] below.

[Equation 4]

When the remaining variables in [Equation 4] are solved, the following [Equation 5] is obtained.

[Equation 5]

Simplifying [Equation 5] gives the following [Equation 6].

[Equation 6]

In [Equation 6], “a” is obtained in advance using [Equation 2], which is a 5x3 matrix. In [Equation 6], “b” can be obtained using input [Rc, Gc, Bc, Cc] and matrices corresponding to the change of the input pixel. At this time, depending on which primary colors are selected in the backlight and LCD display, the calculation formula may be complicated or simplified. After solving the matrix, the remaining variables [Rw, Gw, Bw] are calculated.

The colors obtained by the above results may still be outside the range of the RGBCW color space. Colors outside the color space can be processed using several methods. For example, as disclosed in US patent application US 11/278,675 entitled “Systems and methods for implementing improved gamut mapping algorithms”, through the selection of conditional colors Can be processed. According to a color space representing the primary colors of the backlight array and a shape of the color space of the display panel, there may be cases where the conditional color is not processed. In this case, the method disclosed in US Patent No. 7,893,944 entitled “Gamut mapping and subpixel rendering systems and methods” or other color space processing methods may be used.

The method disclosed in the present exemplary embodiment as described above can be applied to a display system in which a display panel has a smaller number of saturated primary colors than the number of saturated primary colors of a backlight. Also, this method can be used even when the primary colors of the bucklight and the primary colors of the display panel are not shared. Other color space mapping (GMA) techniques may be implemented using the two-step color space mapping members shown in FIG. 2A. For example, the second color space mapping member 240 may directly change RGB input color image data values generated from an input gamma LUT 205. The color space mapping member may map a color space using various methods described above, and may map a color space using various methods that can be easily conceived by a person skilled in the art from the prior art.

Handling Out-of Gamut Colors with Expanded Peak Function

In the application of the peak function block 210, when the output value for a predetermined illuminant is a regional peak value of the input image data (for example, an input image calculated within a space defined by adjacent illuminants having the same color) When the data value is a peak value), if the local peak value is applied to the illuminant, the saturated image color becomes too bright and out of the color space region (out-of-gamut; OOG). That is, a color that exceeds the allowable limit in which the luminous body can actually emit light is required.

The peak function block checks a luminous body value set to a value different from that of a simple local peak function, so that a color outside the color space area can be accommodated. Reference numeral 2100 of FIG. 2B denotes an extended peak function block. The extended peak function block may be disposed at a portion in which the peak function block 210 is disposed in FIG. 2A to replace the function of the peak function block 210 of FIG. 2A. For example, the peak function block 2100 is applied to a display system having RGBCW primary colors and a backlight array having luminaries of RGBC color. However, the peak function block 2100 may be applied to various types of multi-primary color display systems having a set of N primary colors.

The peak irradiation block 210 functions the same as the peak function block of FIG. 2A. The peak irradiation block 210 examines the RGBC values of the linear input image of each pixel to find a peak value of the illuminant within the linear intensity distribution function region of each illuminant. In order to determine whether the luminous body values are the input image color out of the color space, the color space mapping function uses the output luminous body values generated by the peak irradiation block 2110 and the input color value out of the color space by using a local peak function. Identify and accomodate them.

Continuing with reference to FIG. 2B, luminous body values output from the peak irradiation function block 2110 are input to the backlight interpolation function block 2130 to generate _{R L} G _L B _L C _{L values.} Normalized values of the RGBC values of the input image and R _L G _L B _L C _L values are input to the RGBC(W) color space mapping member 2140 by the member shown by reference numeral 2135 and mapped to the color space. . However, in this case, the output W value generated by other methods by the standard RGBCW function is not required. This is because only RGBC colors can escape the color space in the RGBC(W) color space mapping function block 2140. The RGBC values output by the RGBC(W) color space mapping function block 2140 are irradiated by the OOG peak irradiation block 2160 to find the maximum value out of the color space within the point intensity distribution function area of each luminous body. By the peak control block 2170, the maximum value out of the color space is multiplied by the original illuminant values generated by the peak irradiation function block 2110 to increase the illuminant values. Therefore, the degree of deviation from the color space area is reduced. In this case, the peak control block 2170 may additionally multiply the maximum value out of the color space by a predetermined scale factor.

Backlight driving method to improve the quality of the displayed image

An embodiment of driving a backlight using the techniques described above is disclosed. When the above-described techniques are applied to the backlight, the color tone by light supplied from the backlight of the display panel is improved by actively adjusting one or more colors in the form of a function in the image displayed on the panel.

Adjusting Light from Backlight to Image Color Temperature

One of the characteristics of color in an image is color temperature. The color temperature can be defined by the average image and luminance. Using the above-described backlight control technology, the emitted light can be expressed as a function of the color temperature of the image by adjusting the backlight array of the display device. For example, an image representing a sunset has a high number of red and blue colors, but a small number of green colors. On the other hand, when displaying the image reflected on the moon, there are many silver white special blue colors, but few other colors. When using the above-described backlight control techniques, the color temperature of the image may be determined by the display controller. The display controller controls the color temperature of the backlight array so that each scene is rendered with an average color and brightness. Dynamically rendering of an image enables a limited dynamic area and quantization of the display panel, reducing quantum errors and allowing the display panel to have maximum utility within an average luminance and color of an image. The above-described embodiments of an image may be applied only to a part of consecutive images or scenes displayed at a high speed. That is, it can be applied to frames of a video or movie. The above-described backlight control technology can change the color temperature of an image for each scene by controlling the color temperature of the backlight for each frame.

In addition, in a backlight (for example, an LED backlight) using an array of multi-color luminous bodies having a lower resolution than the display panel, the color temperature can be adjusted in different regions of the panel. That is, by varying the color temperature of the backlight array corresponding to a specific part of an image, it is possible to cover a wide dynamic area at the same time in one scene with brightness and chroma.

Controlling Light from Backlight to Alter the W Display Primary

When the above-described backlight control technique is used to control the light generated from the backlight by using the color temperature of the image, the light emitted as the backlight becomes a function of superior color in the image. Accordingly, an image having higher luminance or higher color purity can be displayed than when a uniform white backlight applied to the subpixels of a repeating group in the display panel is used.

First, a problem in the case of using the uniform white backlight will be described. The image of the scene displayed in the darkroom for photo development is usually red. In the case of using a conventional white backlight, the red sub-pixel among the repetitive sub-pixels of the display panel renders the luminance information of the scene through a sub-pixel rendering (SPR) operation. In a standard RGB stripe display device, only one sub-pixel among the repeating group of RGB sub-pixels is used to provide luminance information of an image. In a similar manner, only one of the three subpixels in the repeated group 620 of the RGBW subpixels 620 of FIG. 6 provides luminance information of an image. In addition, only one of the four sub-pixels in the repeating group 320 of the RGBW sub-pixels of FIG. 3 provides image information on the display panel. In a multi-primary color display device using a repeating group of subpixels shown in FIGS. 7, 9, or 24, the luminance information of a red image is only available among 6 subpixels of the repeating group of subpixels (701 in FIG. 7). Only one, or only one of the 6 sub-pixels of the repeating group of sub-pixels (2402 in FIG. 24), or only one of the 8 sub-pixels of the repeating group of sub-pixels (902 of FIG. 9) Used to display luminance information.

In the display system 100 of FIG. 1A and the display system of FIG. 2A to which the above-described backlight control techniques are applied, light emitted from the backlight array is adjusted to become pure red light, so that normally white subpixels ( 304) is used to perform scene rendering using 4 primary colors among 8 sub-pixels in an image of a dark room where red is dominant. Referring to FIG. 9, it is possible to generate similar effects without the aforementioned backlight control technology. Referring to the multi-primary color subpixels of the repeated group illustrated in FIG. 9, luminance information may be provided in an image in which red is dominant by using one of eight subpixels of the repeated subpixel group 902. When the above-described backlight control technology is applied, a pure red image on the display panel uses a larger number of white sub-pixels 904, and a total of eight sub-pixels 906 are used for four sub-pixels. Among them, a repeating group 902 of subpixels including five subpixels may be formed. Also, when white subpixels are used for highly saturated colors, the luminance area of the colors increases. Moreover, the red color may be pure red, and color purity may be improved and a color space area may be expanded without deterioration of color in other colors.

13 is a cross-sectional view illustrating an example of a display panel including a repeating group of multi-primary color sub-pixels having white sub-pixels and a method of using a white sub-pixel as a primary color by the backlight control techniques described in the present invention. 13 shows primary colors controlled by a backlight for a multi-primary color display panel 1300A including a repeating group 1302 of subpixels. The repeated group 1302 of the subpixels of FIG. 13 is a variation of the repeated group 902 of the subpixels of FIG. 9. In FIG. 13, a repetitive group 1302 of sub-pixels is a red sub-pixel 1304, a green sub-pixel 1308, and a blue-green sub-pixel 1320 in the middle of the white sub-pixels 1306 mainly interspersed. And a blue subpixel 1312. On a small scale, saturated subpixels are arranged in a hexagonal grid. For example, the blue-green sub-pixels 1322, 1324, 1326, 1328, 1330, and 1332 surround the blue-green sub-pixel 1340 at the center in a hexagonal shape.

The color temperature of the backlight is higher than that of a display device in which a magenta component is arranged in a conventional RGB stripe shape, and thus a balanced white color can be displayed. The above-described backlight control technology provides sub-pixels having additional primary colors by controlling the color of the light emitter of the backlight. In the above-described red image, when the display panel 1300A is lit by a conventional white backlight, only one of the eight sub-pixels, a red pixel, is used to provide luminance information in a red-dominated image. do. Other pixels including the primary white pixels 1306 are in an off state.

With continued reference to FIG. 13, the backlight control method and techniques described above affect an image in which red is the main color by using white sub-pixels in a display device having a group in which sub-pixels of multiple primary colors repeat. So that the white sub-pixel appears to be the primary color. The primary color by this backlight control technology is called a backlight-controlled (BC) primary color. A pure red image is displayed on a display panel 1300B having eight sub-pixels by combining the red sub-pixel 1304 and four sub-pixels using a plurality of white sub-pixels 1306. The white subpixels 1306 of the panel 1300B are the peak function blocks of Figs. 1A and 1B (110 of Figs. 1A and 1100 of Fig. 1B) or the peak function blocks of Figs. 2A and 2B (210 of Figs. 2A and 2B). 2100), the backlight interpolation member (130 in Fig. 1A), and the remaining display functions in the data path of the display (for example, GMA, SPR, output gamma member, etc.) It transmits vertical hatching.

The arrangement of the subpixels 2400 of FIG. 24 shares the features of FIG. 9. In FIG. 24, the sub-pixels are white sub-pixels 2406 arranged in a square grid shape, and the sub-pixels of red (2404), green (2408), blue (2412), and blue-green (or emerald color) 2420 Includes pixels. Like other layouts of the present invention, the arrangement may have a subpixel structure having an aspect ratio of 1:3. This may follow a conventional stripe arrangement of RGB pixels. As another embodiment, the repeated group of subpixels can be modified in various ways. For example, the diamond of subpixel rendering filters disclosed in US Patent 7,916,156 entitled “Conversion of a sub-pixel format data to another sub-pixel data format” An arrangement of (diamond) shape may be applied. In addition, the above-described filtering of conditional color may be applied.

Controlling Light from the Backlight Array to Alter Other Primary Colors of the Display

The above-described backlight control technique may be used to affect primary colors of a display device, or may be applied to white sub-pixels to improve image quality through sub-pixel rendering. For example, in a backlight array disposed on the rear surface of some of the color subpixels of a repeating group of subpixels disposed within a certain area of the display panel, a part of the color light emitter is turned off to repeat the subpixels in the area. It can affect the color generated by the group. For example, it may be applied to a multi-primary color display system including a display panel having six primary colors, such as the repeated group 701 of sub-pixels shown in FIG. 7. When an image is displayed using a conventional unadjusted backlight in a saturated yellow region of the image, the red 706, green 708, and yellow 711 subpixels are turned on within the yellow region. On the other hand, when the backlight array is controlled using the techniques described above, the blue light emitter is turned off in the area where the yellow image is displayed. Two or more of the six surf pixels are turned on while the blue light emitter is turned off. For example, a magenta subpixel 709 that transmits red and blue light and a blue-green subpixel 707 that transmits blue and green light in the spectrum of the backlight are turned on, and five of the six subpixels are turned on. When the blue light emitter is turned off in a region where a yellow image is displayed, an additional reconstruction point is additionally required in rendering subpixels of a color having high saturation.

The backlight controller gradually darkens the light-emitting body in a predetermined color, and has a maximum pixel value within a corresponding region of the point-phase intensity distribution function of the light-emitting body so that the sub-pixels of the display panel have the maximum transmittance in the same color. In this case, the gradation of the display panel is increased with respect to the same color among the adjacent sub-pixels to compensate for the lowered luminance due to the gradually darkened light-emitting body. Therefore, it is possible to reduce the quantization error. When a part of the illuminant is gradually darkened in a certain area of the image, the color space area may be slightly increased. This is because the light with low luminance emitted by the gradually darkened luminous body has a small loss rate of light due to the color filter. In addition, when a part of the luminous body is gradually darkened in a certain area of the image, the contrast ratio of the displayed image increases. This is because the light with low luminance emitted by the gradually darkened luminous body approaches an off state, and thus a decrease in the contrast ratio due to leakage of light that may occur by the high luminance luminous body is prevented. A backlight including a luminous body gradually darkened not only improves image quality, but also reduces power loss, thereby increasing the life of the battery, and thus has advantages in a display device including a battery.

A technology capable of selectively turning off some of the illuminators of the backlight array for display quality of colors with high saturation is a repetitive group of multi-primary color subpixels having white subpixels in which the backlight control is applied to the white subpixels. Combined with, it realizes the primary color controlled by the backlight. In the above-described red darkroom image, red is dominant in the entire image. Considering an image in which pure red is expressed only in a limited area of the image (for example, a scene in a movie), for example, a dark room for photographic development is observed through an open door, or a red warning light is turned on in the main room of the ship. In the case of, the luminance of other colors of the image will be felt bright and consequently the color will be unsaturated. When such an image is displayed on a multi-primary color display device using a conventional backlight, only the red sub-pixel controls a region in which the red image is displayed. In this case, by reducing the Modulation Transfer Function Limit (MTFL), the red subpixel reaches the Nyquist limit. Therefore, various restrictions arise in the image resolution in the area where such an image is displayed.

In the aforementioned patent applications, cross-luminance modulation of subpixels of different colors has been discussed in order to solve such a resolution problem of an image. The above method has a problem in that colors are not saturated in a region having a high spatial frequency. In addition, in a region in which an image having a high saturation degree at a very high luminance is displayed, all colors out of the color space must be darkened or less saturated. However, during this process, the color of the image is clipped, clamped, and compressed. This method is a problem in that the luminance contrast does not display an ideal image in an area where dark and saturated colors are displayed (images in both areas are displayed at the same time) compared to an area in which a bright and less saturated image is displayed. Occurs.

If it is possible to individually drive the luminous bodies in different areas of the image, the backlight or the display controller can turn off some of the luminous bodies in the area where the bright and saturated image is displayed, and control the luminous bodies in the area where other images are displayed. have. When the luminous bodies in different regions are turned off or adjusted differently as described above, the white subpixel can be used to display an image corresponding to a bright and saturated color, thereby forcibly lowering the saturation of the colors of the image (desaturating). The resolution and brightness of an image can be improved without the need for clamping. When more saturated colors pass through the LCD panel, the white subpixel may increase the brightness of an image displayed by the LCD display system and the overall size of the color space.

Resolution and Colors of Light Emitters in the Backlight Array

In the above-described display system, the multi-primary color filters of the display panel have high efficiency when they correspond to the light emitters of the backlight array one to one. However, the scope of the claims regarding the display system cannot be said to be limited only in the above cases. That is, the technology of the present invention may be applied to the light emitters of the N saturated primary colors in the backlight even when the primary colors of the color filters of the display panel are not N.

The individually controllable backlight array may include illuminants having N colors. The colors may be deep red, blue green (cyan or emerald), violet, or the like, which are not generally used in a backlight array. For example, in a display system including a backlight array having a resolution lower than the resolution of the display panel receiving light from the backlight, the luminous bodies of the backlight have colors different from the primary colors of the display panel or have a larger number than the primary colors of the display panel. You can have the colors of. For example, green light of the illuminant may have a peak wavelength of 530 nm, and cyan light may have a peak wavelength of 500 nm 505 nm. In this case, one color filter may have a transmission region that simultaneously transmits the wavelengths of the green light and the blue-green light. For example, in a space in which an image requiring red light from saturated green is displayed on a display panel, a green light emitter disposed behind the image display area is turned on. Also, a blue-green light emitter disposed behind a region in which an image that requires saturated blue-green to blue color is displayed on the display panel is turned on. One or both of the blue-green and green light-emitting bodies are turned on in a region where an image requiring white color is displayed on the display panel. When a controllable backlight array is used, the number of primary colors of a repeating group of subpixels of the display panel can be reduced.

Colors with different ranges can be applied in a similar way. For example, blue light may have a wavelength of 450 nm. In order to increase the efficiency, light emitters having a wavelength of a deep violet color may be used. The dark violet color luminous body has a wavelength of 400 nm and visually has low efficiency, but the color space of line-of-purples, which is a wavelength with high color differentiation ability for human vision. It widens. In a region where a dark violet color image is displayed, a blue light emitter having a wavelength of 450 nm is turned off and a dark violet light emitter having a wavelength of 400 nm is turned on.

In the red colored region, the human eye is less sensitive to wavelength. In order to generate a dark red image with visual efficiency using a controllable backlight array, a light emitter having a wavelength of 610 nm is used. However, only a light emitter having a wavelength of 610 nm is sufficient, and there is no need to improve the red light emitter to represent a deeper red color having a wavelength of 700 nm. The luminous body having such a long wavelength may be turned on when necessary, and the 610 nm luminous body may be turned off when a deep purple-based image is displayed. In the case of a less saturated color, when both the 610 nm luminous body and the 450 nm luminous body are turned on, the efficiency of the backlight may be improved.

Selecting the color of the light emitters in the backlight need not necessarily coincide with determining the primary colors of the repetitive group of subpixels constituting the display panel. The primary colors of the repeated group of subpixels constituting the display panel do not affect the selection of colors of the luminous bodies constituting the backlight array. Those of ordinary skill in the art may apply the technique for controlling the backlight disclosed in the present invention to one of repeated groups of various types of subpixels in a display panel, which is arranged in a conventional stripe shape. It will be appreciated that not only a display panel having a repeating group of RGB subpixels, but also the display system disclosed in the above-described patent applications, and the embodiments shown in the drawings of the present invention can be applied. One of ordinary skill in the art may apply various embodiments in which the configuration of colors and the arrangement of the light emitters of the backlight array supplement or harmonize a repetitive group of specific subpixels. Therefore, not only the embodiments disclosed in the present invention, but also various other embodiments or design changes may be applied.

A Display System Embodiment Having a Single White (Clear) Primary with a Controlled Backlight Array

In a display system including a backlight array having a lower resolution than a display panel receiving light by the backlight, various combinations of colors of the luminous bodies are possible. However, in the case of a certain display system, the resolution of the backlight array may require a situation in which colors from green to red or blue to blue are displayed together in one small area in which an image is displayed. Due to the limitation of human vision, the backlight array of luminous bodies may have a resolution of a degree that is difficult to be recognized. At this time, the color resolution due to juxtaposition of the luminous bodies is higher than that of the backlight. In a special case where a wide color space is required, it may be possible to implement a display panel having only one color subpixel by selecting specific light emitters of the backlight array. That is, if the backlight array as described above is used, a display panel including a repeating subpixel group consisting of purely transparent white subpixels that is not filtered may be implemented. In this case, the array of transparent subpixels requires high resolution luminance adjustment for the displayed image. In this case, a backlight array including light emitters having N primary colors may have low-resolution colors.

Embodiment of Liquid Crystal Display System

10 is a block diagram showing a liquid crystal display system to which the backlight control technology and methods of the present invention are applied. An embodiment of a liquid crystal display system (LCD) 1000 is disclosed with reference to FIG. 10. The liquid crystal display system 1000 includes a liquid crystal material 1012 disposed between the first and second glass substrates 1004 and 1008. The first substrate 1004 includes a TFT array 1006 for addressing individual pixel elements of the liquid crystal display system 1000. The second substrate 1008 includes color filters 1010 according to an arrangement of any one of repetitive groups of subpixels disclosed in the aforementioned drawings or the aforementioned patents. The liquid crystal display system 1000 further includes a backlight 1020. The backlight 1020 may include an array of luminous bodies shown in FIGS. 4 and 5 or an array of luminous bodies according to the embodiments disclosed in other drawings or the aforementioned patent application. The display controller 1040 processes input color values of an RGB image according to the elements disclosed in FIG. 1A or 2A. The RGB input color values are input to the backlight controller 1060 and are used to set values of the light emitters of the backlight 1020. The values of the luminous body of the backlight 1020 are set using the operation of the peak function blocks of various embodiments according to the embodiments disclosed in FIGS. 1A, 1B, 2A, and 2B described above. The backlight controller 1060 communicates with the display controller 1040 to generate values of luminous bodies applied to the backlight interpolation members 130 and 230 to calculate a low-resolution image of RLGLBL.

Alternative Out-of-Gamut Processing on Low Resolution Backlight Display System

It can be modified in various ways (eg, an LED backlight, a backlight applied to two LCDs, etc.) and various combinations capable of processing image data in a display system having a color backlight having a low resolution are possible.

For example, even if a color backlight such as an LED array value is adjusted, colors out of the color space may exist. This may occur when the luminance is very high even though the color hue is within the point intensity distribution function of the LED (or low resolution backlight system).

The image data of the backlight and the LED subsystem may be temporarily or spatially processed in a spatial-temporal fashion to move colors out of a color space into a target color space region. The temporal/spatial-transient processing may be performed in the entire area (eg, the entire image rendered on the display device) or locally (eg, a subset region of the image rendered on the screen). By temporally adjusting the low-resolution backlight, the above processing may be performed only within a certain area in which a color out of the color space exists at a certain time.

According to an embodiment of the present invention, in a certain area in which the first color out of the color space exists in the entire image, the color opposite to the first color (for example, blue green or green and blue) from the peak value of the backlight color opposite color) is extracted so that a color outside the color space is placed into the color space.

The group color may be set using the primary colors of the backlight or the peak value of the OOG state irrelevant to the primary colors of the backlight. In other embodiments, the color field need not be a pure primary color. The technology used in this embodiment can be variously modified at the level of those skilled in the art.

In this embodiment, an LED backlight having an RGB color is applied to an LCD having an RGBW color layout. The LCD may have a repeating group of subpixels of RGBW color of various types (eg, RGBW subpixels arranged in a square) disclosed in the embodiments of the present invention. In this case, the LCD may include a layout of subpixels having a wide bandpass, such as a white (or clear) subpixel. An LED backlight having an RGB color may also include color illuminants arranged in a suitable (for example, a square or other type of arrangement). In addition, the backlight may have various types of designs. For example, white light (or light having a certain color) according to the geometric arrangement of LEDs of the backlight and the point intensity distribution function of individual LEDs may be irradiated to a predetermined point of the display device. In this embodiment, the OOG method and system applied to the RGB color backlight and the RGBW color LCD display panel can be generalized to be applied to the backlight having N primary colors and the M multi-primary color LCD display panel. In this case, N and M may be different values, and even if N and M are the same, each set of colors corresponding to N and M may be different from each other in the backlight and the LCD panel.

For example, three fields (fields corresponding to the virtual primary colors P1, P2, and P3 below) are applied to the LEDs. In this case, the LEDs may deviate from the color space. Values corresponding to LEDs in each field may be obtained by applying a point intensity distribution function to input RGB data (or an appropriate data format) at a point where each LED is arranged. The final value of the luminance of the LED is determined by field light integration. Therefore, the sum of light in the three fields is equal to the following Max value. The Max value in the three fields can be obtained by [Equation 8].

[Equation 8]

Assuming that a given pure color is obtained by only one field, it is desirable to be proportional to the luminance of the color obtained by the three fields. If the LED flashes, the heat generated is proportional to the degree of flashing, the applied power, and the luminance. Therefore, even if the LEDs of the three fields are flickering only by a third, they can have the same luminance and power consumption.

For example, a person skilled in the art may apply a Field Sequential Color (FSC) system to pure primary colors defined by the colors of the LED primary colors. In addition, by setting the maximum luminance of the LED having a predetermined color in the backlight to the brightest value required in the image data so that it can be displayed on the LCD, and in this process, the values in the LCD are adjusted by X/XL. The light that has passed through the process can pass through the LCD and be emitted.

Dynamic Virtual Primaries

As another embodiment, when virtual primary colors covering only a color space less than all color space areas of a backlight within a certain area of the LCD display panel are used, visibility of a field continuous color (FSC) device may be reduced.

16 shows an image color map smaller than a backlight gamut and a whiteite color space in CIE 1931 color coordinates. Referring to FIG. 16, a color color space 1600 such as a CIE31 color coordinate system covering an original input color space map 1610 such as an RGB color space is illustrated. The original color space is defined by connecting red, green, and blue points of RGB LEDs. A new color space 1620 may be defined as one small part in the RGB color space 1610. The new color space is defined by points 1630, 1640, and 1650 corresponding to virtual primary colors. Virtual primary colors are not exactly the physical primary colors of light emitters such as LEDs or OLEDs. Of course, some or all of the virtual primary colors may correspond to points represented by some or all of the primary colors for a certain period of time. As another embodiment, the points representing each of the virtual primary colors can be obtained by mixing R, G and B (or other color sets of the illuminator of the backlight). Points corresponding to each of the virtual primary colors may exist within a predetermined time-space coordinate system. For example, a virtual primary color point has its own spatial and temporal coordinate system. For example, the virtual primary color point 1630 may exist for one frame of image data of a predetermined time, and a limited number of subpixels may exist in a spatial part of the display panel. Subsequently, the display system may be driven within three fields within the virtual primary colors 1630, 1640, and 1650 that illuminate all or part of the display image.

In another embodiment, the virtual primary color may exist within the entire image frame, or may exist in a space between all image frames, or within one or a few subpixels. It is possible to divide the space into particle states. This is because the backlight can contain an array of low-resolution color LEDs. Also, virtual primary colors may exist for an undefined time, for one or several frames, or for a portion of one frame. This is determined by the operating standard of the system.

In the ball invention, since virtual primary colors are used for spatiotemporal diversity, deterioration may occur in the spacetime of the color coordinate corresponding to the system of the present invention. In the case of deterioration of time and space, the system of the present invention allows the virtual primary colors (for example, R, G and B LEDs or other sets of actual luminous bodies) to be accurately matched with the actual, so that the LEDs are illuminated during the frame in the entire image. There are cases. In this case, the display system is driven by so-called field sequential. Another problem is when three LEDs are simultaneously illuminated for all fields for one virtual primary color point such as white. In this case, the display system is driven in the manner disclosed in the aforementioned 737 patent. These problems can occur for a certain period of time by the system or the user. However, when the display system having the active characteristics of the present invention is used, flexibility is maximized, and driving is optimized by the allocation of the system and virtual primary colors.

Not only three, but also virtual primary colors having an arbitrary number are selected, and it is possible to illuminate a certain area of the display panel for a predetermined period of time.

Selection and Choice of Virtual Primaries

Criteria to be considered in selecting virtual primary colors include reduction of flicker, reduction of color breakup, minimization of power consumption, increase of dynamic range, and quantization error. ), and so on. Regardless of the optimization, by selecting an appropriate (or smallest possible) chromaticity triangle (or a polygon larger than a triangle, a shape with less angles than a triangle, such as a straight line), the point intensity of certain LEDs or LED clusters. Color values within a range of a point spread function may be included in the chromaticity triangle. Through this, a new set of virtual primary colors can be identified, and RSC color values for each virtual primary color can be generated. Through this, a new color space mapping (GMA) for a set of virtual primary colors is performed. Of course, these processes can be rearranged in a different order. As another embodiment, after selecting the virtual primary colors, the tonal area may be checked. This method may be applied to various display systems, and an optimized primary color set may be selected in consideration of the above criteria for system efficiency.

For example, a process of selecting virtual primary colors that minimizes flicker is as follows. In the display system, it can be assumed that an area of an input image of a display panel or a specific small group is rendered. The area may be large enough to cover all of one frame, or only one sub-pixel within the point intensity distribution function of a few backlight LEDs may be represented. Also, a frame in which the entire image is displayed or an area having an arbitrary size between subpixels may be selected. Selecting an image subset can be done by the user or can be done using a mechanical system.

In order to reduce flicker, the values of the LEDs are found so that the change in luminance is minimized within a small part of the image. This process can be performed by a dynamic Field Sequential Color (FSC) system. Flickering generally occurs in the rendering process when a color having a low luminance field (eg, blue) is preceded and a color having a high luminance field (eg, green) is followed. Past attempts to reduce flicker in FSC systems have been made in the art of projectors with color wheels. The system of the present invention reduces flicker through a new method.

FIG. 17 shows three virtual primary colors and a given color within the virtual primary color space in the backlight LED color coordinates shown in FIG. 16. In FIG. 17, an original color space region having a shape of an isosceles triangle 1700 (eg, an RGB color space region) and three virtual primary colors P1, P2, and P3 are shown. The number of colors in the input color space area and the number of virtual primary colors correspond to the number of colors of the backlight and LCD panel, and various modifications are possible in various systems.

In the system according to the present invention, a spatial light modulator, a plurality of individually addressable color light emitters, a field sequential control circuitry, and a circuit for controlling a set of transmissive elements ( circuitry for controlling said set of transmissive elements). The spatial light control unit displays an output image formed from an input signal including a set of color input values. The spatial light modulator includes individually controlled transmissive elements. The color light emitters are disposed as components of a backlight to generate light so that a color image can be displayed on a spatial light control unit. Each luminous body generates light having one color of a plurality of primary colors. A plurality of regions are defined in the backlight, and a set of point intensity distribution functions of a set of light emitters correspond to the regions. The spatial light control unit performs a first mapping function by selecting a set of virtual primary colors corresponding to each color input value in each area. In the illuminants, the imaginary primary colors generate primary colors having a plurality of intensities by the illuminants within a set of the point intensity distribution function. The field continuity control circuit controls the duration and luminance of the virtual primary colors. In controlling the virtual primary colors, the field continuity control circuit uses a set of fields including an intermediate color signal generated by each light emitter in each region. By controlling the virtual primary colors using a field continuous control circuit, an intermediate color image is generated and provided to the spatial light control unit. A circuit for controlling a set of transmissive elements generates an output color image by controlling the transmissive elements in each region to adjust the intermediate color image. The above components will be described in detail in the following embodiments.

Finding Virtual Primaries

Values of c1P1, c2P2, and c3P3, which are substantially the same as the input RGB value, may be defined for a predetermined color C1 in the color space of the virtual primary color. The virtual primary colors have a relationship of [Equation 10] with respect to the values of the original primary colors.

[Equation 10]

[Equation 10] is expressed in matrix form as follows.

When the matrix is inverted against the value of c, it is as follows.

Solving the above equation is as follows.

From [Equation 10], values of c1, c2, and c3 can be obtained. Of course, there are various ways to obtain c1, c2, c3 values through straight-forward matrix algebra manipulation. Fig. 18 is a block diagram showing a hybrid system having spatial and virtual main components controlling an LED backlight and an LCD device. 18 is only one embodiment of a method and system 1800 for determining a virtual primary color, and a person skilled in the art will be able to implement various embodiments using this technical idea.

In the system 1800, input data is applied to the input gamma unit 1802. Image data from the input gamma unit 1802 is moved along one or more data paths. In Fig. 18, two data paths are shown. In the first path, the image data is a peak unit 1804, an interpolation unit 1806, an X/X _L unit 1808, a color space mapping (GMA) unit 1810, and an OOG peak unit 1812. It is applied to the up-sample unit 1814 via &lt;RTI ID=0.0&gt; At this time, one or two data paths for driving the backlight 1822 and the LCD panel 1824 are selected by a signal OOGP applied to the MUX 1816. At this time, driving of the backlight 1822 and the LCD panel 1824 is performed through an output gamma unit (OUT) 1818 and a field continuous control unit 1820. The OOGP signal corresponds to the OOG color value of the LED's point intensity distribution function. If there is no OOG color value, the first data path is selected by the MUX 1816. However, if there is an OOG color value, the second data path is selected. When the second data path is selected, various methods are used to ensure that the color does not deviate from the color space. These methods use virtual primary colors.

The first step in calculating the virtual primary colors is to identify all of the input sample colors that are placed within the point intensity function of one LED or one LED cluster. At this time, the LED colors do not match the virtual primary colors. When following the second data path, data input from the input gamma unit 1802 may be applied to the bounding box unit 1830. The bounding box unit 1830 uses the input data to provide a maximum value and a minimum value (for example, a maximum red value (Max(R)), a minimum red value (Min(R))), and a maximum blue value (Max. (B)), the minimum blue value (Min(B)), the maximum green value (Max(G)), the minimum green value (Min(G)), etc.) are calculated. These calculated values are each vertex of the bounding box surrounding all the colors in the point intensity distribution function for one LED. 22 is a graph showing the bounding box module shown in FIG. 21A. Each of the points shown by reference numeral 2202 represents all input pixels disposed within the point intensity distribution function of one LED, respectively. In this embodiment, the bounding box 2204 consequently has two axes.

The process of deriving the formula for the new planes encompassing all colors in the bounding box is as follows. The planes extend from the reference point to have an angle of 45 degrees with the two axes by using one point as the reference point and the corner of the bounding box as the second point. At this time, the plane corresponding to the RG color, the plane corresponding to the GB color, and the plane corresponding to the BR color are respectively based on the axes corresponding to each other, corresponding to the B color, the axis corresponding to the R color, and the axis corresponding to the G color. Rotate. This rotation is performed until each plane touches the corner of the bounding box. For example, a line indicated by reference numeral 2206 indicates a plane corresponding to the RG color. When viewed from the edge side, the plane corresponding to the RG color continues to rotate about the B axis until it contacts the nearest corner of the bounding box 2204.

[Equation 11]

Each of the formulas in [Equation 11] represents a plane in a color space similar to a line existing in the xy space of the CIE color coordinate system. When calculated by [Equation 11], lines in the xy space of the CIE color coordinate system become parallel to the chromaticity triangle corresponding to the input data toward the edge. At this time, it is preferable that the position of the bounding box is arranged adjacent to the input primary color. If the opposite corner of the bounding box is used to define the three planes in the color space, it will appear that the hue triangle is rotated by about 60 degrees in the calculation by the above formula. Reference numeral 2208 denotes a rotation of the plane corresponding to the RG color toward the opposite corner of the bounding box 2204. At this time, the closer the bounding box is to the corner of the hue triangle, the better results can be obtained in rotation. The plane can be calculated by the following [Equation 12].

[Equation 12]

As another embodiment, cross calculations for the plane may be performed by irradiating all input sample colors arranged within the point intensity distribution function of one LED using a bounding box. The angles of all input colors of the point intensity distribution function can be calculated by the above equation. Among the above angles, the minimum value (or maximum value) may be used instead of the angle corresponding to the corner of the bounding box. Referring to the lines shown by reference numeral 2210 and reference numeral 2212, it can be seen that the corners of the bounding box 2204 correspond better to the points 2202 of the input color than to use the corners of the bounding box 2204 as they are (2206, 2208). . In other words, compared to using the bounding box as it is, the size of the hue triangle becomes smaller and the virtual primary colors become closer to each other. This is because the bounding box encompasses a wider area than the actual size of the required color space. The virtual primary colors that are close to each other in this way reduce power consumption and flicker in the display device. Accordingly, two of the characteristics to be achieved in the display system, namely, a power consumption reduction portion and a flicker reduction portion can be satisfied at the same time.

In certain cases, the area covered by the virtual primary colors may protrude to the outside of the bounding box. This problem can be solved by decreasing (or increasing) the angles calculated by the method of using a bounding box or the method of examining all the input sample colors.

However, when three planes are selected, the three lines in the xy space of the CIE color coordinate system form a triangle (or other closed figure), and the intersection of each line corresponds to the three colors. The three colors may be used as virtual primary colors. It is possible to display any color located in the triangle by using the virtual primary colors. In this case, the virtual primary colors are arranged in the bounding box. The intersection points can be obtained by various methods. For example, it can be obtained by using lines in the xy space of the CIE color coordinate system, or through a line intersection formula. In using the above methods, a floating point can be obtained and used using planes in space based on a linear RGB coordinate system. However, there is a method of defining a fourth plane perpendicular to the line of grays from the pair of the above three formulas in a method that does not use the piloting point.

[Equation 13]

The part where two of the rotated planes intersect is represented by a straight line radiating from the origin. All points on the straight line have the same hue. Any straight line passing through the color cube starting from the origin intersects perpendicularly to the plane defined by [Equation 13]. In the process of calculating this, there are no problems such as an integer overflow or the occurrence of a step divided by zero. In the calculation process, it is preferable to adjust the scale of all virtual primary colors until the straight line contacts the edge of the color space. Using the above method, it is possible to obtain sufficient luminance for the LED to illuminate the pixels disposed between the area calculated by the field continuous color (FSC) and the area defined by the virtual primary colors. As another embodiment, by reducing the scale of the virtual primary colors, it is possible to have the same luminance as the brightest color in the color box. By reducing the scale of the virtual primary colors in this way, it is possible to reduce the power consumption of the LED backlight and reduce the quantization error of the LCD panel disposed on the top of the LED backlight.

In another embodiment, the component colors of the virtual primary colors may be limited according to the maximum duty cycle of each LED. For example, a red LED can be turned on completely in a first field of one frame and turned off during two subsequent fields. As another embodiment, the red LED can only be turned on for 1/3 of the three fields of one frame. In the above examples, the power consumed by the red LED during the entire frame is the same. This limitation applies equally to the summation of the red color component across all virtual primary colors, and the scale is reduced until the summation matches the repetition rate of the red LED. In the same way, it can be applied to backlights comprising LEDs having red, blue or other primary colors. The results of these calculations can be applied to the three colors P1, P2, and P3, which are sets of primary colors. The set of primary colors can express any color located in the bounding box through an appropriate combination. The above processes may also be applied using the "Calc. virtual primaries" module 1832. The primary colors may be sequentially loaded into the LED at a later time.

The LED's point intensity distribution function makes it possible to generate an image with the same resolution as the input sample points by interpolating the colors of virtual primary colors in the LED backlight. The interpolation is performed by the backlight interpolation module 1834.

The interpolated result is converted into output quantized values applied to the display panel through the output gamma module 1818 by combining the values of original RGB colors among the “calculated c-values” 1840. While the virtual primary colors are sequentially displayed on the LED backlight by the field continuous color (FSC) module 1820, the c output values are input to the LCD display panel 1824.

A display system such as that shown at 1800 has a point intensity distribution function that overlaps each other with respect to the LEDs. In this case, the point intensity distribution function of the backlight LED in a steady state may overlap with the point intensity distribution function of the LED having a dynamic virtual primary color. In this case, the light that is consequently irradiated by the backlight may be a mixture of color illumination in a normal state and field sequential color illumination. Each field may have a different color and luminance. In this case, the area defined by the fields need not be large enough to include all the colors using the c value. That is, the values of c do not need to reconstruct all the colors of the overlapping point intensity distribution function. At this time, it is also possible to find X/XL and GMA values in each field in the color space. In particular, LEDs (overlapping fields) that are arranged adjacent to pixels surrounded by pixels that are darker than the average of the surrounding pixels, or LEDs in a steady state, and are driven in a state in which a continuously controlled field of virtual primary colors overlaps. For pixels corresponding to sequentially modulated virtual primary driving LEDs), it is also possible to find _{X/X L and GMA values in each field.}

When X/X _L and GMA values obtained in each field are used, color breakup and/or flicker can be reduced. When only some colors are arranged in the color space area, that is, when one or two or more fields are out of the color space (OOG), X/X _L and GMA values are also out of the color space. In this case, average values of luminance illuminated by a few virtual primary color fields and X/X _L and GMA values may be usefully used in the calculation process. To put it another way, the sum of overlapping the virtual primary color fields of the steady state and the dynamic state over time is assumed to be lighting in the steady state, _{and X/X L} and GMA values for the corresponding pixels are calculated. It is used to

_{The above two methods of using GMA values normalized by X/X L} values instead of c values can also be applied to an area illuminated by LEDs controlled only by virtual primary colors. That is, it is possible to configure a display system using only the virtual primary colors, and remove the overlap between the virtual primary color and the peak unit 1804 derived by the LED point intensity distribution function in a normal state.

In the system, a desired color can be reconstructed through the following steps. Color breakage and flicker are reduced by using GMA values normalized by _{X/X L} values in each virtual primary color field. _{Subsequently, GMA values normalized by X/X L} values corresponding to the average (or summed) color of the virtual primary color fields or c values obtained in each virtual primary color field are obtained.

Another method (or mode of operation) is to use “interim virtual primaries”. The intermediate virtual primary colors are a color set formed by _{an X/X L value and a GMA value corresponding to a desired color.} The color set is input to a Calc c values block. Finally, the value input to the LCD panel is _{obtained by multiplying the value of X/X L by the} value of c. This method reduces color breakage and flicker.

In order to stitch the modes, it is desirable to mix the modes. Mathematically, even though it is not possible to physically recognize that the color value is out of the color space (OOG), the modes are linearly blended so that the mixed value is placed in the color space. , Each mode reproduces the same color. In an embodiment of the present invention, a method of linear blending and how much to mix are disclosed. Accordingly, as in the above methods, various modes may be visually stitched to improve image quality.

Various color reproduction methods can be mathematically described according to the following [Equation 14]. (In this case, x in Px and cx denotes the number of a field.)

[Equation 14]

c1P ₁ + c2P ₂ + c3P ₃ = C

Px represents the colors of the backlight in the field, and C represents the result of the reproduced color. The cx values refer to values corresponding to places where pixels of a monochromatic (no color filter) LCD system are arranged. The field continuous color (FSC) system using virtual primary colors uses one c value corresponding to each color filter (for example, RGBW or RGBCW color system), and the mixed color subpixels at a predetermined point. Make them look as if they are single monochrome pixels.

If the field continuous color (FSC) system of the virtual primary color (using one c value corresponding to each color filter) and other modes are mixed, the field continuous color (FSC) system is obtained by the following [Equation 15]. Can be represented.

[Equation 15]

c1P ₁ (RGBCW) + c2P ₂ (RGBCW) + c3P ₃ (RGBCW) = C

In [Equation 15], (RGBCW) means R = G = B = C = W, and values corresponding to each color correspond to a maximum value (MAXCOL). At this time, a value corresponding to each R color, a value corresponding to the G color, a value corresponding to the B color, a value corresponding to the C color, and a value corresponding to the W color are obtained individually. That is, the values corresponding to each color are independent of each other in the distribution of multiplication operations. RGBCW values (variables) are grouped for convenience, but are not multiplied or added to each other.

Over average backlight values (e.g., time averaged/time integrated three fields of the backlight color, and the variable primary for the W sub-pixel) is described in [ It can be obtained by Equation 16].

[Equation 16]

P ₁ (RGBCW) _A + P ₂ (RGBCW) _A + P ₃ (RGBCW) _A = C

In [Equation 16], (RGBCW) _A refers to values applied to color subpixels by an X/X _{L value and a normalized GMA value.}

On the other hand, each backlight value (ie, in order to independently obtain a desired color in each color field) can be obtained by the following [Equation 17].

[Equation 17]

P ₁ (RGBCW) ₁ + P ₂ (RGBCW) ₂ + P ₃ (RGBCW) ₃ = C

At this time:

P ₁ (RGBCW) ₁ = P ₂ (RGBCW) ₂ = P ₃ (RGBCW) ₃ = C/3

According to [Equation 17], RGBCW values in each field are blended in the same amount for the same color from each system. For example, by mixing field continuous colors (FSC), over average values as shown in [Equation 18] may be obtained.

[Equation 18]

c1P ₁ (RGBCW)(1-a) + c2P ₂ (RGBCW)(1-a) + c3P ₃ (RGBCW)(1-a) + aP ₁ (RGBCW) _A + aP ₂ (RGBCW) _A + aP ₃ ( RGBCW) _A = C

Therefore, values in each field for RGBCWx can be obtained through [Equation 19] as follows.

[Equation 19]

RGBCWxb = cx(RGBCW)(1-a) + a(RGBCW)x

Values in each field over each system can also be obtained through [Equation 20] as follows.

[Equation 20]

RGBCWxb = cx(RGBCW)(1-a) + a(RGBCW)x

Here, a is a blended value between 0 and 1, and RGBCWxb means a blended value in each color channel before subpixel rendering.

In order to determine a, an embodiment using the maximum value of the possible over average is as follows. When a is 1, the three fields of the LCD have the same value. If a is less than 1, the values in the LCD have different values in the fields. Because the liquid crystal does not respond instantaneously to changing to a new value, errors may occur in reproducing color in a field continuous color (FSC) system. The smaller the difference between the values changed from one field to another field, the less likely the above errors will occur. This is a shape that occurs because the response speed of the liquid crystal is not fast. Errors in such a field continuous color (FSC) system are reduced in a backlight system using virtual primary colors. Because virtual primary colors have less color difference than original primary colors, the possibility of error is reduced. The maximum allowable value of a is expressed as a function of the maximum allowable value of cx and the maximum allowable value of (RGBCW)x as shown in [Equation 21].

[Equation 21]

aMAX(RGBCW)x + cx(1-a) = MAXCOL

In this case, a can be represented by [Equation 22].

[Equation 22]

a = MAXCOL-cx / MAX(RGBCW)x-cx

In the mixing process, the a value is fixed between 0 and 1. The above equations can be modified in various ways. For example, the blending function a can be replaced by the following [Equation 23].

[Equation 23]

(a-ab)

In this case, b may be an arbitrary constant or function, and has a value between 0 and 1. The function starts by mixing the over average in the normal mode with the value of c in the field continuous color (FSC) mode. In this case, in the region to which the field continuous mode is applied, the over average mode is located in the color space region. However, in this case, a rough texture may be formed compared to a bright subpixel farther away. The b value can be expressed as [Equation 24] using a function of local color. At this time, the green subpixel has better visibility than the blue subpixel.

[Equation 24]

RGBCWxb = cx(RGBCW) _A (1-(a-ab)) + (a-ab)(RGBCW)x

Another method of determining the blending amount is a virtual code as follows using a filtered mode image.

--calculate the alpha values

xhimu=math.max(xhi1,xhi2,xhi3)

alpha = math.max(R,B,G,C,W)-xhimu

if alpha~=0 then

alpha = (MAXCOL-xhimu)/alpha

else

alpha =1.0 --clamp infinity at 1.0

end

alpha = math.min(1,math.max(0,alpha))

rx = (alpha-alpha*beta)

xx = (1-(alpha-alpha*beta))

R1o = rx*R+xx*xr1

B1o = rx*B+xx*xb1

C1o = rx*C+xx*xc1

G1o = rx*G+xx*xg1

W1o = rx*W+xx*xw1

R2o = rx*R+xx*xr2

B2o = rx*B+xx*xb2

C2o = rx*C+xx*xc2

G2o = rx*G+xx*xg2

W2o = rx*W+xx*xw2

R3o = rx*R+xx*xr3

B3o = rx*B+xx*xb3

C3o = rx*C+xx*xc3

G3o = rx*G+xx*xg3

W3o = rx*W+xx*xw3

local MX=math.max(R1o,B1o,C1o,G1o,W1o)

if MX>MAXCOL then

R1o = math.floor(MAXCOL*R1o/MX)

B1o = math.floor(MAXCOL*B1o/MX)

C1o = math.floor(MAXCOL*C1o/MX)

G1o = math.floor(MAXCOL*G1o/MX)

W1o = math.floor(MAXCOL*W1o/MX)

end

local MX=math.max(R2o,B2o,C2o,G2o,W2o)

if MX>MAXCOL then

R2o = math.floor(MAXCOL*R2o/MX)

B2o = math.floor(MAXCOL*B2o/MX)

C2o = math.floor(MAXCOL*C2o/MX)

G2o = math.floor(MAXCOL*G2o/MX)

W2o = math.floor(MAXCOL*W2o/MX)

end

local MX=math.max(R3o,B3o,C3o,G3o,W3o)

if MX>MAXCOL then

R3o = math.floor(MAXCOL*R3o/MX)

B3o = math.floor(MAXCOL*B3o/MX)

C3o = math.floor(MAXCOL*C3o/MX)

G3o = math.floor(MAXCOL*G3o/MX)

W3o = math.floor(MAXCOL*W3o/MX)

end

In natural images, there are a number of dark saturated colors. The dark saturated colors can be reproduced using color filters of a hybrid FSC display. In this case, virtual primary colors are not required. In this embodiment, irradiation using a bounding box may ignore colors reproduced by color filters. Because, in the investigation using a bounding box, colors out of the color space (OOG) from X/XL and normalized RGB colors are converted to RGBW colors, and the color space is mapped by a color space mapping block (GMA). That is, virtual primary colors are determined in consideration of colors out of the color space of the color filters (or pixels of the display panel) through the above process, but colors located in the color space of the color filters are not considered in determining the virtual primary colors. Does not.

The process is recursive, and colors out of color space (OOG) may be determined by first estimating an effective average backlight in color space mapping (GMA).

This cyclical process is suitable for a video display technology in which a plurality of frames per second are displayed. Each frame is displayed using the results of the current backlight values. At this time, the image of each frame has a local virtual primary and average backlight values, and is obtained through the cyclic method in an area where the color is gradually darkened in the backlight (local color dimming backlight). It is displayed using values.

The color space mapping method outputs current color filter values to be used in the mixing process by using a current (for example, a current frame) backlight value. Also, in the color space mapping method, a flag value is set in a pixel out of the color space (OOG). Boundary box irradiation checks whether the pixels are out of color space (OOG). Through this, virtual primary colors of a new set are selected and sent to the backlight controller. The backlight control unit includes a temporary filter and a decay. The decay averages, smoothes, and slows the amount of change in the process of changing from one frame to another. The simplest filter is to weight average or mix the last backlight values and newly calculated values. The filter serves two purposes. First, the change in the backlight is slowed down, reducing the components required for temporary fluctuations. In addition, through a cyclical process, conditions best suited to the backlight can be obtained gradually, and changes due to oscillation can be reduced. In addition, an image obtained by colors out of the color space (OOG) can be obtained by a dynamic backlight in a non-point state or an abnormal state in both aspects of a luminance and a virtual primary color.

Another advantage of using the method is that it is possible to investigate to display N future frames in addition to the current frame. Since a temporarily filtered response of the backlight values is possible, the luminance of the image displayed by the virtual primary colors does not decrease, and the size of the area covered by the virtual primary colors does not decrease. In this case, even if the characteristics of the scene change or the movement of the object changes from a certain area to another area, the image quality does not change. By the method of examining future frames, an investigation process may be performed using the highest values among color values corresponding to N frames. From the hardware perspective, additional frame buffers are required for this method. This is because the current frame is time delayed during the additional frames. Note that the voice track must also be delayed for the same N frames, so that the voice/video synchronization can be maintained.

In the above method, when examining the bounding box, a specific color may be selectively ignored or a specific pixel may be ignored. That is, the embodiment of the invention can be modified to selectively ignore an appropriate color or an appropriate pixel by modifying the boundary box selection process. 34 is a two-dimensional graph defined by virtual primary colors and simplifying input pixels. In FIG. 34, a two-dimensional graph defining a boundary of a cloud of an input pixel by using pairs of virtual primary colors P1 and P2 is shown. At this time, P1 and P2 are reduced by a ratio of half and are shown as fields of coexisting primary colors. The vectors in the drawing are based on the color space of the continuous field color in the backlight, and the vector sum of P1 and P2 forms the intermediate axis of the color filter color space. Although the vector P3 exists in the drawing, it is omitted in the drawing for simplification.

However, in the case of the above method, all or substantially all of the input pixels of the colors in the color filter color space region are not considered, and thus there is an inaccuracy in determining the backlight value. This is because a small subset of all pixels may be located at the boundary of the pixel cloud. In addition, an oscillatory phenomenon may appear in determining the backlight values in an additional system.

Therefore, in this embodiment, a method different from the above method is used. For example, dark saturated input pixels can be excluded in determining the chromaticity of the virtual primary colors of a hybrid field continuous color (FSC) system.

Fig. 35 is a two-dimensional graph in which the exclusion gamut defined by virtual primary colors and improved by the present invention is simplified. Referring to FIG. 35, a first order approximation is performed with respect to the final average value of the backlight. The imaginary primary colors are primarily assumed to be orthogonal vectors of pure red, pure green and pure blue. The vectors are assumed to be a maximum red data value, a maximum green data value and a maximum blue data value. The maximum red data value, maximum green data value, and maximum blue data value in the backlight are values scaled from a maximum red data value, a maximum green data value, and a maximum blue data value in an input image at a predetermined ratio. The first approximated average value of the backlight is represented by a vector defined by the sum of the three primary colors, and may be the same as the vector by the maximum red data value, the maximum green data value, and the maximum blue data value in the input image. have.

Referring to FIG. 35, based on an approximate average value of the backlight, a color space of a color filter and a continuous exclusion gamut may be defined to cover a dark end of the color filter color space. The bounding box irradiation method is performed using pixels or colors arranged outside the excluded color space. That is, whether the colors and colors corresponding to the pixels are outside the excluded color space, the bounding box survey method for virtual primary colors is performed, and the colors corresponding to the pixels in the excluded color space are compared to the bounding box survey method for the virtual primary colors. Not judged by In this case, in the bounding box survey method using the excluded color space, not only colors outside the color filter color space but also colors arranged in the color space of the color filters, but colors placed outside the excluded color space are also outside the exclusion gamut. It is judged as out-of-gamut.

The excluded color space may be defined as a small rectangular shape by subtracting peak data values by an appropriate conversion factor. Various conversion coefficients or various types of excluded color space can be considered. Preferably, the conversion factor is 1/(1+(Lw/Lrgb)). When the conversion factor is 1/(1+(Lw/Lrgb)), the lower end of the approximated color filter color space has a rectangular shape. At this time, Lw represents the transmittance of the white (with a wide band) subpixel, and Lrgb represents the transmittance of the color filter subpixel.

36 is a two-dimensional graph in which the exclusion gamut defined by virtual primary colors and improved by the present invention is simplified. In FIG. 36, a color space with reduced color breakup is shown while excluding more pixels and determining potentially more optimized backlight values. The left side of the graph shown in FIG. 36 shows an example of the excluded color space. In this case, the excluded color space is a coefficient (or one of the coefficients obtained by the above-described functions) to the straight lines passing through the two points P1 and P2 on the drawing and the origin of the color filter color space, and the maximum color value of the color filter color space. It may be defined by a third point multiplied by) or a value approximating the maximum color value of each pixel. The right side of the graph shown in FIG. 36 shows another example of the excluded color space. In this case, the excluded color space is a point obtained by multiplying the two sides of the color filter color space and the maximum color value of the color filter color space by a coefficient (or one of the coefficients obtained by the above-described functions) or the maximum of each pixel. It can be defined by an approximation of the color value. A person skilled in the art may sufficiently exclude input pixels, obtain values of virtual primary colors more accurately, or use various sizes of excluded color spaces to be closer to the boundary of the input pixels.

However, if the excluded color space is too large, there is an increased risk that an important part of the input pixel cloud is not displayed. Therefore, the size and limit of the excluded color space must be lower than the average of the data values of each input channel. For example, the size of the excluded color space should be lower than the average of the average input red data value, the average input green data, or the average input blue data.

In addition, setting the exclusion color space by calculation based on the input image statistics or determining the hue in the backlight enables continuous and repetitive luminance nodules to achieve a steady state faster. That is, the method of setting the exclusion color space or determining the hue in the backlight of the present invention can reach a state of displaying a high-quality image more quickly than the method of determining the hue of the backlight without the exclusion color space. Picture quality can be improved.

The following virtual code represents a simple excluded color space having a rectangular shape. If the frame buffer is not included, it is preferable to use the input peak channel survey irradiated in the previous frame in the process of irradiating the virtual primary color of the backlight.

r_excl = rin_max[i]*(1/5) --input peak channel survey results scaled by 1/(1+Lw/Lrgb) = 1/(1+4) = 1/5

g_excl = gin_max[i]*(1/5)

b_excl = bin_max[i]*(1/5)

ooeg = 0

if r> r_excl or g> g_excl or b> b_excl then - if input is outside the exclusion gamut

ooeg = 1 --out of exclusion gamut flag

end

if (ooeg==1) then --if this pixel is outside the exclusion gamut

survey(r,g,b) --survey the input pixel for virtual primary chromaticity decision

end

For example, when a color is located in a color space (in-gamut) in the color space mapping (GMA) in the a blending process, a value is 1, and all colors located in the color space are averaged. It can be displayed by a color filter on a typical backlight. If the value of b is used, the code should include a process of testing that the value of c is valid. In this case, the color is located inside a triangle formed in the color space by the virtual primary colors.

In this case, in the process of changing an image from one frame to another, virtual primary colors may be rapidly changed or expanded to include new colors such that a recursive process is difficult to follow. In this case, the colors are out of the color space (OOG) in both sides of the c value of the color space mapping (GMA) and field continuous color (FSC) system of the color filter. In this case, the value c may have a negative value in one or more fields corresponding to a predetermined pixel. At the same time, a value of c that is not negative has a relatively high value. If the c value has a negative value, it means that the vector in the color space is inverted and the corresponding color vector is subtracted from the vector having another positive c value. This will appear as too bright or insufficiently dark color in the image. Since it is impossible for the user to physically recognize the negative image, this phenomenon may be recognized as a problem at first. However, those skilled in the art may partially or completely offset the negative c value through the a blending process. In addition, as for the mixed color space mapping (GMA) value, colors having a negative c value are 0 or almost no, so that a value c having a very high value may be reduced. Finally, the reproduced color may be a color that is close to or equal to the value of the original color to be achieved. Therefore, when the modes are mixed, the negative c value is canceled, and color values can be reproduced by an actual system. For example, the code for performing the above process is as follows.

function surveypix(x,y) --how to survey a single pixel, x and y are LCD co-ords

local

i=math.floor(x/ledXsep)+xbak*math.floor(y/ledYsep) --co-ord of BLU zone

local r,g,b = spr.fetch(pipeline,x,y) --fetch input RGB values

if (r+g+b)~=0 then --ignore black

black[i]=0 --flag will be 1 if all black

local angle --psuedo angle

--calculate'angle' of RG plane rotating towards the B axis to each point

local angle = r*MAXCOL/(r+g+b)

rmin[i] = math.min(angle,rmin[i])

rmax[i] = math.max(angle,rmax[i])

angle = g*MAXCOL/(r+g+b)

gmin[i] = math.min(angle,gmin[i])

gmax[i] = math.max(angle,gmax[i])

--the angle of the BR plane rotating towards the G axis

angle = b*MAXCOL/(r+g+b)

bmin[i] = math.min(angle,bmin[i])

bmax[i] = math.max(angle,bmax[i])

end - ignore black

--survey the xhi values for power reducrion

local xhi1=spr.fetch("xhi1",x,y) --fetch the xhi value

local xhi2=spr.fetch("xhi2",x,y) --from all three

local xhi3=spr.fetch("xhi3",x,y) --fields

peak1[i]=math.max(peak1[i],xhi1)

peak2[i]=math.max(peak2[i],xhi2)

peak3[i]=math.max(peak3[i],xhi3)

end

--how to analyze the survey results in one zone

function surveyzone(x,y) --x,y are LED zone co-ords

local i=x+xbak*y --index into statistic tables

if black[i]==1 then

Rp1,Gp1,Bp1=1,1,1 --set them to a very dim non-zero number if the lcd above the zone is black

Rp2,Gp2,Bp2=1,1,1

Rp3,Gp3,Bp3=1,1,1

else

--calculate the reddish-greenish-bluish primaries

Rp1 = MAXCOL-bmin[i]-gmin[i] --reddish

Gp1 = gmin[i]

Bp1 = bmin[i]

Rp2 = rmin[i] --greenish

Gp2 = MAXCOL-rmin[i]-bmin[i]

Bp2 = bmin[i]

Rp3 = rmin[i] --blueish

Gp3 = gmin[i]

Bp3 = MAXCOL-rmin[i]-gmin[i]

--scale them until they bump up against the edge of the Gamut first

Dp = math.max(Rp1,Gp1,Bp1) --The intersection formula I used can never get zero!

Rp1 = Rp1*MAXCOL/Dp

Gp1 = Gp1*MAXCOL/Dp

Bp1 = Bp1*MAXCOL/Dp

Dp = math.max(Rp2,Gp2,Bp2)

Rp2 = Rp2*MAXCOL/Dp

Gp2 = Gp2*MAXCOL/Dp

Bp2 = Bp2*MAXCOL/Dp

Dp = math.max(Rp3,Gp3,Bp3)

Rp3 = Rp3*MAXCOL/Dp

Gp3 = Gp3*MAXCOL/Dp

Bp3 = Bp3*MAXCOL/Dp

--then reduce power according to the xhi survey

peakv=math.min(peak1[i]+HEADROOM,MAXCOL)

Rp1=Rp1*peakv/MAXCOL --scale it down so max xhi value will be on nearly full

Gp1=Gp1*peakv/MAXCOL

Bp1=Bp1*peakv/MAXCOL

peakv=math.min(peak2[i]+HEADROOM,MAXCOL)

Rp2=Rp2*peakv/MAXCOL --scale it down so max xhi value will be on nearly full

Gp2=Gp2*peakv/MAXCOL

Bp2=Bp2*peakv/MAXCOL

peakv=math.min(peak3[i]+HEADROOM,MAXCOL)

Rp3=Rp3*peakv/MAXCOL --scale it down so max xhi value will be on nearly full

Gp3=Gp3*peakv/MAXCOL

Bp3=Bp3*peakv/MAXCOL

end

return Rp1,Gp1,Bp1,Rp2,Gp2,Bp2,Rp3,Gp3,Bp3

end --in a later step, these are decayed with the previous LED decision

In addition, the above method can be modified and applied to color subpixel values. In this case, the color subpixel values may be unmixed values. For example, in the case of reproducing “line of yellow” in the color space of a display device, the most saturated color with the red primary color, and the most saturated color with the green primary color, blue (B) and blue-green (C) Even if the sub-pixels are shut off and the luminance of blue and emerald colors is nominally zero, some light leakage occurs due to the response speed of the LCD. In a field continuous color (FSC) system that uses a liquid crystal material as the main optical switch medium, when the response speed is low, a backlight light leak occurs in a lower valued field. When a field of a low value is not 0, a technique for compensating for a light leakage phenomenon by overshooting a target value by an estimated amount is disclosed. However, when the color to be displayed is saturated, the field of the lower value becomes 0, so there is no lower value that can overshoot.

In a hybrid FSC system, color-filtered sub-pixels are applied to turn off sub-pixels corresponding to a color having a luminance of 0 in the field, thereby improving color reproducibility. However, a problem due to a spatially rapid color change in sub-pixels cannot be avoided. Therefore, a method of smoothly introducing an amount of shutting off blue (B) and blue-green (C) subpixels is required. In a similar way, for colors of “line of purples” in the color space, it is necessary to shut off the green subpixels smoothly. In addition, it is necessary to shut off the red sab pixels for the blue series color.

The virtual code for performing the above method is as follows.

R = G = B = C = W

If Bin <MAX(Rin, Gin)

Then B = C = Bin / MAX(Rin, Gin)

If Gin <MAX(Rin, Bin)

Then G = Gin / MAX(Rin, Bin)

If G <C

Then C = G

If Rin <MAX(Bin, Gin)

Then R = Rin / MAX(Bin, Gin)

At this time, Rin, Bin, and Gin represent colors to be displayed by the panel as luminance values linearized from input values for the RGB color of the system.

In particular, it is primarily determined whether the input luminance value of the blue sub-pixel in each pixel is smaller than the input luminance value of the red or blue sub-pixel. If the input luminance value of the blue sub-pixel in each pixel is smaller than the input luminance value of the red or blue sub-pixel, the values of the blue and blue sub-pixels are the input values of the blue sub-pixels among the input values of the red and green sub-pixels. It is set as the value divided by the larger value. Next, it is determined whether the input value of the blue sub-pixel is smaller than the input value of the red or blue sub-pixel. If the input value of the blue subpixel is smaller than the input value of the red or blue subpixel, the value of the blue subpixel is set as the value obtained by dividing the input value of the green subpixel by the larger of the input values of the red and blue subpixels. do. After that, it is determined whether the value of the green sub-pixel is smaller than the value of the blue-green sub-pixel. If the value of the green sub-pixel is smaller than the value of the blue-green sub-pixel, the value of the blue-green sub-pixel is set to the value of the green sub-pixel. In this case, the value of the blue-green sub-pixel is set to the value of the green sub-pixel regardless of whether the value of the blue sub-pixel is a reduced value. Finally, when the input value of the red subpixel is smaller than the value of the blue or green subpixel, the red subpixel is set to a value obtained by dividing the input value of the red subpixel by the larger of the input values of the blue and green subpixels.

The above processes test whether a color is located on one side of the color space between white (or gray) in the color space and a predetermined line in the color space. Through the above steps, the undesired color is set to a value inversely proportional to the saturation of the desired color. The above processes may be performed before mode stitching or blending is performed. The inverse proportion does not necessarily mean an exact inverse proportion, but implies reducing color values in various forms for undesired colors.

For example, the code applied to an RGBW system such as PenTile RGBW is as follows.

R = G = B = W

If Bin <MAX(Rin, Gin)

Then B = = Bin / MAX(Rin, Gin)

If Gin <MAX(Rin, Bin)

Then G = Gin / MAX(Rin, Bin)

If Rin <MAX(Bin, Gin)

Then R = Rin / MAX(Bin, Gin)

Accordingly, in each pixel, it is primarily determined whether the input value of the blue subpixel is less than the input value of the red or green subpixel. If the input value of the blue subpixel in each pixel is less than the input value of the red or green subpixel, the blue subpixel is a value obtained by dividing the input value of the blue subpixel by the larger of the input values of the red and green subpixels. It is set to. Next, it is determined whether the input value of the green subpixel is smaller than the input value of the red or blue subpixel. If the input value of the green sub-pixel is smaller than the input value of the red or blue sub-pixel, the green sub-pixel is set to a value divided by the larger value among the input values of the red and blue sub-pixels. . Thereafter, it is determined whether the input value of the red subpixel is smaller than the smaller input value of the blue or green subpixel. If the input value of the red sub-pixel is smaller than the smaller of the input values of the blue or green sub-pixel, the red sub-pixel divides the input value of the red sub-pixel by the larger value among the input values of the blue and green sub-pixels. It is set to a value. For example, the above processes may be performed through the following code.

--get xhi values early, we need them in several places

local xhi1,og1=spr.fetch("xhi1",x,y)

local xhi2,og2=spr.fetch("xhi2",x,y)

local xhi3,og3=spr.fetch("xhi3",x,y)

--these will contain the results, however calculated

local R1o,B1o,C1o,G1o,W1o,L1o

local R2o,B2o,C2o,G2o,W2o,L2o

local R3o,B3o,C3o,G3o,W3o,L3o

local R,B,C,G,W,L,Og=spr.fetch("gmaA",x,y) --the GMA results ri,gi,bi=spr.fetch(ingam,x,y) - the RGB values after ingamma

--separate storage for xhi for each primary

local xr1,xb1,xc1,xg1,xw1=xhi1,xhi1,xhi1,xhi1,xhi1

local xr2,xb2,xc2,xg2,xw2=xhi2,xhi2,xhi2,xhi2,xhi2

local xr3,xb3,xc3,xg3,xw3=xhi3,xhi3,xhi3,xhi3,xhi3

if CYANNESS==1 then

if ri<math.max(bi,gi) then

local cnes=ri/math.max(bi,gi)

xr1=math.floor(xhi1*cnes)

xr2=math.floor(xhi2*cnes)

xr3=math.floor(xhi3*cnes)

end

end

if MAGENTNESS==1 then

if gi<math.max(ri,bi) then

local mnes=gi/math.max(ri,bi)

xg1=math.floor(xhi1*mnes)

xc1=math.floor(xhi1*mnes)

xg2=math.floor(xhi2*mnes)

xc2=math.floor(xhi2*mnes)

xg3=math.floor(xhi3*mnes)

xc3=math.floor(xhi3*mnes)

end

end

if YELLOWNESS==1 then

if bi<math.max(ri,gi) then

local ynes=bi/math.max(ri,gi)

xb1=math.floor(xhi1*ynes)

xc1=math.floor(xhi1*ynes)

xb2=math.floor(xhi2*ynes)

xc2=math.floor(xhi2*ynes)

xb3=math.floor(xhi3*ynes)

xc3=math.floor(xhi3*ynes)

end

end

As another embodiment, there is a method of concentrating the luminance of a steady backlight in one of four time slots to become the fourth field of a virtual primary color field continuous color (FSC) system.

When there are four virtual primary colors, they can be combined to implement metamers of a desired color. Therefore, one of these isomorphic colors is selected. In this case, the predetermined isomorphic color may be selected to minimize a component of a virtual primary color far from a desired color. At this time, if the degree of minimizing the component of the virtual primary color far from the desired color becomes 0, the desired color can be reproduced only with the remaining three virtual primary colors. In this case, the desired color can be obtained simply by calculating c values for the three virtual primary colors.

The systems and methods described above are capable of many different variations that can be used to control out-of-color space (OOG) situations. In the following, other modified embodiments of the system are disclosed. For example, a subpixel rendering (SPR) method may be coupled to or applied to the system. In addition, various blocks shown in FIG. 18 (eg, a color space mapping block (GMA), an X/X _L block) may be used. However, redundant descriptions regarding the use of these blocks will be omitted. Those skilled in the art will be able to implement various modifications to control the out-of-color space (OOG) state.

Systems with multiple primary colors for different numbers of backlights are possible. For example, a multi-primary color backlight with red (R), green (G), blue (B) and blue green (C) LEDs is possible. The techniques described above can be used to calculate various types of shaded areas. For example, it can be applied to a combination of primary colors having various shapes such as a quadrilateral and a triangle. 23 is a graph showing a multi-primary color LED color coordinate and overlapping XYZ primary colors representing an individual image color coordinate smaller than the multi-primary color LED color coordinate on a CIE 1931 color coordinate. In FIG. 23, colors available in the color space are expanded using an LED illuminant having a fourth color. In this embodiment, the LED emitter having the additional color may be a blue-green color. In this case, it is possible to set by various combinations of the virtual primary colors 2330, 2340, and 2350. For example, various sets of virtual primary colors 2330, 2340, and 2350 using an isomorphic color combination based on a combination of color LED light emitters are possible. Since the color space to which the virtual primary colors are applied is larger than that of general RGB primary colors, a large multiprimary color gamut can be accommodated. In another embodiment, the set of primary colors may be virtual. That is, although a set of primary colors can be mathematically calculated, it may be difficult to realize physically. For example, CIE XYZ primary colors may be a set of virtual primary colors. Since a feasible virtual primary color is possible by a linear combination of XYZ primary colors, the RGB notation in the above calculation can be replaced by the XYZ notation through appropriate transformations between color spaces.

When applying field continuous color (FSC) technology, it is desirable to minimize side effects (e.g., color break-up, flicker, etc.) caused by field continuous color (FSC). Do. As one of the methods for solving this problem, there is a method of loosely constraining the color distribution within each LED point intensity distribution function to a chromaticity area. In other words, the constraint between the color and hue regions distributed within each LED point intensity distribution function is not excessively strict. When the color and hue regions distributed within each LED point intensity distribution function are tightly constrained, the discrepancy in the c value may increase. As the discrepancy of the c value increases, the degree of visually recognized flicker increases.

Alternatively, it is also possible to select virtual primary colors that form a virtual color space that is larger (or proportionally larger) than the distribution of colors within the point intensity distribution function of each LED. For example, a larger virtual color space may be formed by moving the primary colors toward the original RGB primary colors (or RGBC primary colors) at a predetermined distance or at a predetermined ratio. As another embodiment, after obtaining the centroids of the virtual primary colors, there is also a method of moving the virtual primary colors away by a distance obtained by multiplying the distance between the virtual primary colors and the center by a constant coefficient. As another embodiment, there is also a method of using an average value of colors found in an image within the point intensity distribution function. In addition, it is possible to make the virtual primary colors move away from the original distance by a certain factor. In addition, by applying a certain function, there is a method of proportionally shifting the original distance so that it becomes closer as the original distance is closer, and less distance if the original distance is farther. At this time, it is possible to reduce flicker by assigning a weight to a color brighter than a dark color and multiplying the bright color by a larger value of c.

Since the solid color over the entire area of a small number of LED point intensity distribution functions has a zero distribution, the virtual primary colors collapse to the same value. Since it is desirable to use as few primary colors as possible, it is desirable to set two or three primary colors to the same value. In this case, the primary colors and c values corresponding to the primary colors may be maintained to be the same value. Combining the primary colors as described above increases temporal frequencies to reduce disadvantageous artifacts or deterioration of image quality. The smaller the desired pixel color (desired pixel color) spreads (distributed), the more the virtual primary colors converge (collapse).

The error of the value c that slows the response speed of the liquid crystal display changing from one state to another is calculated, the field continuous color is adjusted to a desired value (FSC modulation), and the virtual primary colors are compensated. At this time, bright primary colors may become brighter, and dark primary colors may become darker.

Field continuous color (FSC) method according to another embodiment

In a field continuous color backlight system, it is possible to drive a backlight including an LED using Pulse Width Modulation (PWM). 19A and 19B are timing diagrams illustrating two methods of reproducing a given color by the system shown in FIG. 18. In FIGS. 19A and 19B, the horizontal axis represents time, and the vertical axis represents each color (RGB) luminance (or intensity, voltage, etc.). 19A and 19B show a method of controlling an out-of-color space (OOG) state using a single pulse width control (single PWM) cycle for a field continuous color (FSC) system. In Fig. 19A, the green and blue LEDs are only slightly turned on in a slightly desaturated red color. At this time, it is assumed that the red color is out of the color space (OOG) (for example, A1 of FIG. 19A). The red LED cannot display red outside the color space. 19B shows a first primary color (P1, red), and a second primary color (P2), instead of displaying red, green, and blue among three time slots in a pulse width control (PWM) cycle in a virtual primary color system. Red-orange) and virtual primary colors of the third primary color (P3, dark magenta) are used to display. In FIG. 19B, the sum of the additional areas A2 and A3 has the same amount as the area A1 out of the color space (OOG) in FIG. 19A. Accordingly, the red curve of FIG. 19B includes all of the red input values of FIG. 19A to prevent an OOG phenomenon.

As another embodiment, FIGS. 20A, 20B and 20C are timing diagrams illustrating methods using virtual primary colors. In FIGS. 20A, 20B and 20C, the horizontal axis represents time, and the vertical axis represents each color (RGB) luminance (or intensity, voltage, etc.). FIG. 20A shows a field continuous color (FSC) waveform diagram in which red, green, and blue LEDs generate a white area in an LED backlight continuously with substantially the same amount of light. FIG. 20B shows a waveform diagram of generating the same white light as that of FIG. 20A by an LED that is turned on for a period of time three times at a third luminance in each cycle. At this time, the three virtual primary colors P1, P2, and P3 have the same shade of gray. It is common for an image to have a wide area without color such as black, white, or gray. It is preferable to detect an area without the color and use monochromatic virtual primaries as shown in FIG. 20B. This is because the image having the waveform diagram of FIG. 20A may have a flicker defect, but the image having the waveform diagram of FIG. 20B does not have a flicker defect. However, the image having the waveform diagram of FIG. 20C is preferable to the image having the waveform diagram of FIG. 20B. In FIG. 20C, a desired average brightness can be obtained with only one field continuous color (FSC) cycle by driving the LED in proportion to the pulse width control (PWM). In FIG. 20C, since the frequency of flickering is three times that of FIG. 20A, the flicker cannot be detected by the human eye. Accordingly, in FIG. 20C, visually recognized flicker is reduced.

Not filtered Not LCD Active with display Virtual primary color system( Dynamic Virtual Primary System Having Unfiltered LCD Display )

21A is a block diagram showing a virtual primary field sequential color system for sequentially reproducing a virtual primary color space. In FIG. 21A, a color filter does not exist in the pixel pattern 2162 of the LCD panel 2160. The system is driven using only virtual primary field sequential colors. When driven, R*G*B* data (R*G*B* perceptually encoded data) encoded to be recognized is linearized by an input gamma module 2105. The optional input filter 2110 removes noise from the image. The bounding box module 2130 determines a color color space map of colors displayed in the point intensity distribution function of each LED. The Calc Virtual Primaries module 2132 calculates virtual primary colors from the data. The virtual primary colors are displayed on the LED backlight array 2120 by the field continuous color module 2125. The backlight interpolation module 2134 determines an actual color possible behind each pixel (unfiltered subpixel) of the LED panel 2160. At this time, the backlight interpolation module 2134 determines the possible actual colors using an appropriate interpolation method and a point intensity distribution function of the LED. Calculate c Values module 2141 calculates a c value by combining the values calculated by the backlight interpolation module 2134 with the RGB image data. The output gamma module 2115 gamma quantizes the c value so that it can be displayed on the LCD panel 2160.

21B is another embodiment showing the Calc virtual primary color module shown in FIG. 21A. With reference to FIGS. 21A and 21B, various embodiments in each module will be briefly described below. For example, in the LED backlight 2120, three elements (triplets) of red, green, and blue LEDs are arranged in a rectangular layout, but they may be viewed as a single point when observed from a place spaced apart from each other due to a close distance. Each LED has a rectangular point spread function. As an embodiment, eight LED pixels may be placed between each LED and an additional row of LEDs at the edge of the LCD matrix. The arrangement of the LED pixels may be variously modified.

Noise of an input image such as speckles reduces a dynamic range that can be displayed on the display panel and increases power consumption of the LED backlight. In order to solve this problem, an additional input filter 2110 may be disposed after the input gamma module 2105 to reduce noise. Various image noise reduction filters can be applied. For example, chromatic noise can be reduced by filtering chromatic components in an appropriate color space such as YCrCb or CIELAB. Real images can sometimes contain information outside the human visual ability. When information beyond human visual ability has a high spatio-chromatic frequency, the virtual primary colors must be farther away from the color space than actually necessary. The tone noise is found in low luminance (dark) areas of the image. Filtering the hue noise can obtain a tighter and smaller virtual primary color space, while reducing fluctuations in the value of c and reducing potential defects such as visual artifacts.

Since [Equation 11] and [Equation 13] contain a number of 0s and 1s in the matrix, the formula representing the intersections of these planes can be easily simplified. The actual angle between one of the color planes and the input color point can be computationally difficult, but it is easier to calculate and classify it in the same order. have. [Equation 25] below is an equation for calculating the angle corresponding to each color using the input colors (r, g, b).

[Equation 25]

rangle = 2*r*MAXCOL/(2*r+g+b)

gangle = 2*g*MAXCOL/(r+2*g+b)

bangle = 2*b*MAXCOL/(r+g+2*b)

At this time, MAXCOL represents the maximum constant value of the input color value after the input gamma conversion process by the input gamma module 2105. The above equations are simple enough to cover all input points within the actual LED's point intensity distribution function. In the bounding box module 2130, all input pixels within the point intensity distribution function of the LED are converted into pseudo-angles as described above, and the minimum value (or maximum value) of the virtual angles ) Can be investigated within the boundary box module 2130. Through 8 pixels corresponding to each LED, 2x8 x 2x8 or 256 input pixels can be irradiated to irradiate the minimum angle in one backlight LCD. At this time, the calculation process can be made easier by storing intermediate results in line buffers or frame buffs.

When the minimum angles are found, the minimum angles are applied to the Calc Virtual Primaries module 2132. As described above, one of the virtual primary colors is obtained by two planes according to [Equation 11] and a diagonal plane according to [Equation 13]. It is possible to relatively simplify the calculation result by extending the equation for finding the intersection of planes into algebraic notation. [Equation 26] below is an equation for calculating the virtual primary color adjacent to the green axis.

[Equation 26]

Rp1 = MAXCOL*rmin/(2*MAXCOL-rmin)

Gp1 = MAXCOL*gmin/(2*MAXCOL-gmin)

Bp1 = MAXCOL*

(4*MAXCOL^2-4*MAXCOL*gmin-4*rmin*MAXCOL+3*gmin*rmin)/

(rmin*gmin-2*rmin*MAXCOL-2*MAXCOL*gmin+4*MAXCOL^2)

In this case, rmin, gmin, and bmin denote minimum values obtained by examining the surrounding input color values according to the pseudo-angle formula. The calculation result represents the RGB coordinate system of the virtual primary color P1. If the RGB coordinate system of the virtual primary color P2 is calculated in a similar manner, it is as shown in [Equation 27] below.

[Equation 27]

Rp2 = MAXCOL*

(4*MAXCOL^2-4*MAXCOL*bmin-4*MAXCOL*gmin+3*gmin*bmin)/

(4*MAXCOL^2-2*MAXCOL*bmin-2*MAXCOL*gmin+ gmin*bmin)

Gp2 = MAXCOL*gmin/(2*MAXCOL-gmin)

Bp2 = MAXCOL*bmin/(2*MAXCOL-bmin)

If the RGB coordinate system of the virtual primary color P3 is calculated in a similar manner, it is as shown in [Equation 28] below.

[Equation 28]

Rp3 = MAXCOL*rmin/(2*MAXCOL-rmin)

Gp3 = MAXCOL*

(4*MAXCOL^2-4*MAXCOL*bmin-4*MAXCOL*rmin+3*rmin*bmin)/

(4*MAXCOL^2-2*MAXCOL*bmin-2*MAXCOL*rmin+ rmin*bmin)

Bp3 = MAXCOL*bmin/(2*MAXCOL-bmin)

As described above, the virtual primary colors are scaled by a conversion factor until they reach the edge of the color space corresponding to the maximum luminance of the display device. As another embodiment, a conversion factor may be scaled to the maximum luminance of input colors within the point intensity distribution function of the LED. While the bounding box down-sample module 2130 examines the minimum angles and stores them in the variable Lmax, the maximum luminance can be calculated, and the conversion factor is multiplied. The formula for performing is as shown in [Equation 29] below.

[Equation 29]

Rp1 = Rp1*Lmax/ max(Rp1,Gp1,Bp1)

Gp1 = Gp1*Lmax/ max(Rp1,Gp1,Bp1)

Bp1 = Bp1*Lmax/max(Rp1,Gp1,Bp1)

Rp2 = Rp2*Lmax/max(Rp2,Gp2,Bp2)

Gp2 = Gp2*Lmax/max(Rp2,Gp2,Bp2)

Bp2 = Bp2*Lmax/max(Rp2,Gp2,Bp2)

Rp3 = Rp3*Lmax/max(Rp3,Gp3,Bp3)

Gp3 = Gp3*Lmax/max(Rp3,Gp3,Bp3)

Bp3 = Bp3*Lmax/max(Rp3,Gp3,Bp3)

At this time, it is preferable that the calculation processes are obtained within the limit of the total power of each LED. In the embodiment of the three virtual primary colors, the sum of values for the red color among the three has a duty cycle of 1/3. The same is true for green and blue. For example, in a three virtual primary color system, it is desirable to have a duty cycle of 1/3 the sum of values for green and blue LEDs. If the sum of the values for the red color of the three virtual primary colors already has a value smaller than MAXCOL, the above calculation is not necessary. The above calculation is expressed in the form of a virtual code as follows.

Div = math.max(Rp1+Rp2+Rp3,Gp1+Gp2+Gp3,Bp1+Bp2+Bp3)

if Div> MAXCOL then

Rp1 = Rp1*MAXCOL/Div

Gp1 = Gp1*MAXCOL/Div

Bp1 = Bp1*MAXCOL/Div

Rp2 = Rp2*MAXCOL/Div

Gp2 = Gp2*MAXCOL/Div

Bp2 = Bp2*MAXCOL/Div

Rp3 = Rp3*MAXCOL/Div

Gp3 = Gp3*MAXCOL/Div

Bp3 = Bp3*MAXCOL/Div

end

When a black and white image is displayed, the virtual primary colors are located adjacent to each other on the hue diagram and have substantially the same values. In the above calculation, the three virtual primary colors have values of about 1/3 of the maximum value in each field, and when these are summed, they have a value of 100% of the maximum value in the entire frame. However, in a region in which an image having a high chromatic spatial frequency is displayed, the virtual primary colors are separated from each other. In this case, when the above equations are calculated, each virtual primary color has most of the power in one field, and the remaining fields of the same frame have little power or are almost turned off.

When the pixels within the point intensity distribution function of the LED display substantially monochrome, it is easy to calculate the degree of power reduction. However, low power cannot be applied in a region in which an image having a high chromatic spatial frequency is displayed. For example, in order to reduce the power in the LED backbuffer, the maximum c value survey module 2150 is used to investigate the largest c value (or maximum c value) within the point intensity distribution function of each LED. . The maximum c value can be used in the process of obtaining the lowest possible values by multiplying the conversion factor in the LED. In this case, the c value may not be obtained in a step prior to the c value calculation module 2141. As another embodiment, one Calc Virtual Primaries module 2132 may include two backlight interpolation modules 2134 and two calculate c values modules 2141. . The first LED approximation module 2135 may perform a calculation function for the virtual primary color calculation module 2132. Each of the two backlight interpolation modules 2134 and the c-value calculation module 2141 performs a calculation that first approximates the c-value. The maximum c-value investigation module 2150 examines the maximum c-value among the c-values, and finds the largest value in the point intensity distribution function of each LED. After that, the final value of each LED is calculated by the LED value conversion module (Scale LED Values module) 2152. The above two steps can be performed using the following virtual code.

for j=0,15 do --survey the max xhi value in the point spread function (PSF)

for i=0,15 do --loop for all pixels in PSF

local xhi=spr.fetch("LCD",x*8+i-8,y*8+j-8,xbuf) --fetch the xhi value

maxhi=math.max(maxhi,xhi) --find the maximum one

end - pixels in PSF

end - lines in PSF

local r,g,b=spr.fetch(ledbuf,x,y) --read in LED buffer values

maxhi=math.max(MAXCOL,maxhi+floor) --prevent zero valued c determinants D

r=r*maxhi/MAXCOL --Scale LED Values

g=g*maxhi/MAXCOL

b=b*maxhi/MAXCOL

spr.store(ledbuf,x,y,r,g,b) --store them back in LED buffer

The above processes are performed for each LED in an LED triplet composed of three LEDs corresponding to three fields. Reduced values and reduced power consumption values may be obtained by a second-order approximation performed through the above processes. In this case, the reduced values may be reduced LED values or reduced color values obtained by the LED value conversion module 2152.

The above processes are calculated for the virtual primary colors for one of the three fields of each frame. In FIG. 21A, the LED values are passed to a field continuous color (FSC) module 2125. The field continuous color (FSC) module 2125 may include a small LED frame buffer for storing the LED values.

The backlight interpolation module 2134 calculates an effective backlight color in each pixel 2162 of the LCD panel 2160 using the LED values transferred from the LED frame buffer. In this case, the calculation process may be appropriately performed for each pixel, or may be preferably performed using values previously calculated for all effective backlight colors and stored in other frame buffers. In this case, three frame buffers may be required to store effective backlight colors for three fields in one frame. The position of each of the frame buffers can be calculated using four LEDs arranged adjacently to be surrounded according to the arrangement shown in the embodiment of the present invention. [Equation 30] below may use the point intensity distribution function stored in a look-up table. For example, the lookup table may include 4096 8 12-bit integers encoded to directly correspond to the luminance of the LED. [Equation 30] below calculates one effective backlight color (rs, gs, bs) at one point (x, y) in one field.

[Equation 30]

xb = x/8

yb = y/8 --position of a nearby LED

xd = mod(x,7)

yd = mod(y,7) --distance to a nearby LED center

Rp,Gp,Bp = fetch(xb,yb) --get upper left LED color

psf = spread[xd]*spread[yd]/4096 --look up point spread function

rs = Rp*psf --sum upper left LED

gs = Gp*psf

bs = b*psf

Rp,Gp,Bp = fetch(xb+1,yb) --color of upper right LED

psf = spread[7-xd]*spread[yd]/4096 --PSF for this led and pixel

rs = rs + Rp*psf --sum upper left LED

gs = gs + Gp*psf

bs = bs + Bp*psf

Rp,Gp,Bp = spr.fetch(ledbuf,xb,yb+1) --color of lower left LED

psf spread[xd]*spread[7-yd]/4096 --PSF for this led and pixel

rs = rs + Rp*psf --sum upper left LED

gs = gs + Gp*psf

bs = bs + Bp*psf

Rp,Gp,Bp = fetch(xb+1,yb+1) --color of lower right LED

psf = spread[7-xd]*spread[7-yd]/4096 --PSF for this led and pixel

rs = rs + Rp*psf --sum upper left LED

gs = gs + Gp*psf

bs = bs + Bp*psf

rs = rs/4096 --sum was 12-bit precision

gs = gs/4096 --collapse them back to pixel precision

bs = bs/4096

The calculation of the virtual code as described above may be performed in each pixel of each field of the frame. The c-value calculation module 2141 calculates the c-value using the result value obtained by the above calculation. The c-value calculation module 2141 calculates a c-value for each LCD pixel in all three fields using the above-described extended [Equation 10]. The calculation process includes calculation of a matrix inversion, but not all matrices are subject to calculation of an inverse matrix. By calculating the determinant of the matrix, it is checked whether the result is non-zero. If the determinant is not 0, [Equation 10] is used as it is. In actual calculations, pixel values are integers between 0 and maximum possible value (MAXCOL). That is, in each calculation of the above calculation process, an additional factor, MAXCOL, is required. In the following virtual code, values denoted by (R1, G1, B1) represent the effective backlight color in the first field at each point. Values indicated by (R2, G2, B2) and values indicated by (R3, G3, B3) represent effective backlight colors in the second and third fields of the frame, respectively. Values denoted by (R, G, B) represent values corresponding to the input color at the point passing through the input gamma module 2105.

D=R1*G2*B3-R1*B2*G3-R2*G1*B3+R2*B1*G3+R3*G1*B2-R3*B1*G2

if D!=0 then

x1 = ((G2*B3-B2*G3)*R+(R3*B2-R2*B3)*G+

(G3*R2-R3*G2)*B)*MAXCOL/D

x2 = ((B1*G3-G1*B3)*R+(R1*B3-B1*R3)*G+

(R3*G1-R1*G3)*B)*MAXCOL/D

x3 = ((G1*B2-B1*G2)*R+(B1*R2-R1*B2)*G+

(R1*G2-G1*R2)*B)*MAXCOL/D

end

Using the above calculation method, almost similar result values are obtained in all three fields of a frame in an area in which an image substantially close to a black and white image is displayed. When almost similar result values are obtained in the three fields, flicker is reduced in the displayed image. The result of reducing flicker is the same when a black and white image is displayed as well as when an image is displayed in a single color. For example, it is possible to obtain a result of reducing flicker in an image using a red color or an image displayed when a red light is on in a dark room. In addition, even when a color image is displayed in some areas and a monochromatic image is displayed in the remaining areas, the above-described area is far from the area where the color image is displayed (for example, the area outside the area of the point intensity distribution function of the LED). A low-flicker mode can be applied. The above-described calculation can be applied to each input pixel value, and the calculated results for the c1 value, c2 value, and c3 value in each field of the frame are calculated using the Output Gamma module 2115. Pass through and applied to the output gamma module 2115.

The backlight array 2120 of the system of FIG. 21A is individually controlled. In another embodiment, the LEDs or other color light sources are not individually controlled spatially, but the overall intensity may be controlled. When the overall intensity of the light sources is controlled, the point intensity shunt function has an overall uniform function. In this case, the backlight interpolation module 2134 is not required. In this case, most of the images are mapped to a color space smaller than the full gamut range of the color primary colors of the backlight array 2120, thereby reducing field sequential color artifacts. . This embodiment is useful for color projectors in which color light generated from adjustable light sources such as LEDs or laser pumped frequency converters (nonlinear optics) is controlled in intensity in sequential fields. Can be applied in a way.

In this embodiment, the active field continuous display device includes a backlight. The backlight may illuminate a plurality of colors to have a plurality of intensities. The colors and their intensity can be independently adjusted in a set of areas of the backlight. The active field continuous display device may further include a control circuit for actively selecting a color and intensity of a backlight in a predetermined area. As described above, the conventional field continuous display device cannot independently control the intensity and color in an area where an image is displayed at a predetermined point at a predetermined time. In addition, since the conventional field continuous display device does not display an image in consideration of input color values at a predetermined time, the image quality cannot be optimized when determining a predetermined image quality standard.

Reduction in Simultaneous Contrast Error

The field continuous display device described above provides a number of advantages over conventional displays. As an example, a continuous field display device may be operated in a manner that eliminates various unwanted image effects, such as a simultaneous contrast error. The simultaneous contrast error is a known phenomenon that may occur in a number of general displays. In an image having a bright white area adjacent to a color area in which the saturation is maximally saturated, the saturated color is perceived by the human eyes to be darker than the original color. When the color is yellow (i.e., saturated or close to saturation), the visual perception is darker than the original color.

In theory, the above problem can be reduced or eliminated by reducing the area of each W subpixel. However, although this method can be helpful in reducing the problem of the simultaneous contrast error in principle, there are a number of difficulties in actual implementation. For example, the overall white luminance of the panel will be reduced, which needs to be compensated for by other approaches that have a step-by-step negative effect.

In addition, it is difficult and undesirable in practice to fabricate a panel having W sub-pixels smaller than those of other color sub-pixels. In addition, the relatively small W subpixel has a different capacitive load compared to other subpixels, making it difficult to drive. Accordingly, the display according to an embodiment of the present invention can be programmed to detect a bright (i.e., saturated or near saturation) color area such as yellow adjacent to a bright white area, and the entire LED backlight Can be adjusted to suit the bright color.

For compensation, non-clear sub-pixels can also be adjusted to suit the bright color. For compensation, non-clear sub-pixels can also be adjusted to reduce the transmission of the bright color to maintain the desired color temperature and color of the panel. For example, if the bright color is yellow, the luminance values of the backlight are adjusted so that the R and G LEDs are increased (more yellow), while the gradation or color value of the non-clear (or non-white) subpixels Are reduced to reduce the transmission of R and G by approximately the same amount. Therefore, this method involves tilting the backlight to a more yellowish side, and adjusting the R and G subpixels for compensation. This reduces the image effect due to the simultaneous contrast error by transmitting yellow through the W sub-pixel and less yellow through the color sub-pixel.

The corresponding decrease in color for the subpixels and an increase in a particular LED color paired may be performed on a global basis. That is, it is applied to all LEDs and all color subpixels of a display device. Alternatively, it may be performed only on areas detected as susceptible to simultaneous contrast errors, that is, bright white and adjacent saturated or near saturated colors.

Additionally, the present invention expects a large amount of decrease in backlight luminance, and also anticipates a large amount of increase in transmittance of non-clear subpixels corresponding to the decrease. The reduction amount of the backlight luminance may or may not be exactly the same as the amount of light passed by the sub-pixels corresponding to the decrease.

Finally, the method described above can be applied not only to yellow but also to other colors, in particular to saturated or close to saturated colors. In other words, the method(s) can be applied to increase the amount of color emitted by the backlight, and the backlight considers color deficiency and saturate, and is equal to the subpixels of the display panel. It is designed to reduce the amount of color transmitted.

Segmented Backlight

Hereinafter, a display system having a new backlight arrangement and a method of driving the same are disclosed. For example, a display system employing a segmented backlight and a driving method thereof are disclosed. In the backlight, the number of light elements decreases, thereby reducing the cost of the backlight. Therefore, when combined with an array version of the display system, it is possible to achieve an active contrast ratio or other optical property improvement.

Display System Comprising Multiple Segmented Backlight

As described above, various embodiments of the backlight may include an array of luminous bodies (eg, luminous bodies as shown in the backlight 120 of FIG. 1A ). At this time, the luminous bodies are driven in a manner similar to that of a low-resolution image display device, and the array of luminous bodies driven like this low-resolution image display device is convolved with an LCD device having a higher resolution disposed thereon. A backlight having a resolution of N x M includes N x M illuminants 122 (or N x M clusters may be used to display color or to enhance luminance) arranged in an array. On the other hand, in FIG. 25, a new type of backlight capable of approximating N x M resolutions using only N+M luminous bodies 2512 and 2522, which is a number less than N x M, is disclosed. 25 is a plan view illustrating an embodiment of a novel segmented backlight assembly used in a display device. Hereinafter, a method of obtaining a high resolution with only a small number of luminous bodies is disclosed.

26 is a plan view showing a conventional backlight having a light guide plate and two light-emitting bodies. The backlight 2600 of FIG. 26 includes a flat light guide plate 2610 and two light emitters 2612. Since the flat light guide plate 2610 reflects light on the surface and guides it in a different direction, complete reflection does not occur, resulting in light loss. Light generated from the light emitters 2610 is guided toward a spatial light modulator by the planar light guide plate 2610. The light emitters 2612 may include conventionally used cold cathode fluorescent lamps (CCFL) or light emitting diodes (LEDs).

According to US Patent US 5,717,422 issued by Fergason under the name of Variable Intensity High Contrast Passive Display that implements a high contrast ratio with variable intensity, the luminance of the luminous bodies 2612 is controlled. Thus, a technology for displaying an image with a luminance less than the maximum luminance using a dim backlight 2600 is disclosed so that more light is transmitted through the spatial light control unit (eg, LCD) placed on the top. . The convolution of the reduced luminance of the backlight 2600 and the increased light transmittance of the spatial light control unit reduces power consumption of the luminous body 2612 and improves the contrast ratio of the light control unit, while still displaying an image of a desired quality. . However, when any one pixel of the input image must exhibit the maximum luminance, the backlight luminous body 2612 must exhibit the maximum rotation as a whole to maintain reliability in reproducing the image.

FIG. 27 is a plan view illustrating an improved backlight than the backlight of FIG. 26. Referring to FIG. 27, the backlight 2700 includes two (or more) optically separated light guide members 2720 and 2721, and the light guide members are coupled to the light-emitting bodies 2722 and 2723, respectively. ). The backlight 2700 may be driven so that the light emitters 2722 and 2723 have different levels of luminance at the same time. Therefore, if a pixel located on one side of the image should display the maximum luminance and the other pixel should display a low luminance, at least half of the light emitters can emit low luminance light. Statistically, such an arrangement can reduce the average luminance of the luminous body, reduce power loss, and improve image quality.

A display device using a segment backlight improves image quality to a statistically significant degree. 28 is a plan view showing a conventional backlight having a light guide plate and four light-emitting bodies. Referring to FIG. 28, the backlight 2900 includes a flat light guide 2810 and four light-emitting bodies 2812. In this case, the luminous bodies 2812 include Cold Cathode Fluorescent Lamps (CCFLs), Light Emitting Diodes (LEDs), and the like. 29 is a plan view illustrating a backlight according to an exemplary embodiment of the present invention, which is improved over the backlight of FIG. 28. Referring to FIG. 29, the backlight 2900 includes four optically separated light guide plates 2910, 2914, 2920 and 2924. The light emitters 2912, 2916, 2922, and 2926 may be interlocked with the light guide plates 2910, 2914, 2920, and 2924, respectively. For example, a pair of light guide plates 2920 and 2924 are separated along a horizontal axis, are driven independently, and are respectively linked to the pair of light guide plates 2920 and 2924. By 2926), the upper half and the lower half of the backlight 2900 may be driven to have different luminances. The remaining pair of light guide plates 2910 and 2914 are disposed on the top or rear surface of the pair of light guide plates 2920 and 2924 separated in the horizontal axis direction. The remaining pair of light guide plates 2910 and 2914 are separated along a vertical axis, are driven independently, and are connected to the remaining pair of light guide plates 2910 and 2914, respectively. By 2916), the left half and the right half of the backlight 2900 may be driven to have different luminances. Accordingly, the four light-emitting bodies 2912, 2916, 2922, and 2926 can be driven to have different luminance levels.

When driving, when one pixel in one quadrant of the image (for example, reference numeral 2930) has the maximum luminance, but the remaining three quarters of the image have low luminance, the illuminant corresponding to the remaining three quadrants of the image They may generate light with low luminance. For example, in a certain image, it can be assumed that pixels with maximum luminance are concentrated in one corner of the image and low luminance is displayed in the rest of the image. That is, it is assumed that pixels having the maximum luminance are concentrated in the upper left corner of the image. In this case, the upper luminous body 2922 and the left luminous body 2912 are turned on at maximum luminance, and the lower luminous body 2926 and the left luminous body 2916 may be set to very low luminance. In this case, the upper right quadrant 2930 of the image may be displayed with maximum luminance. The upper left quadrant 2932 and the lower right quadrant 2934 may be displayed with intermediate luminance. The lower left quadrant 2936 can be illuminated with very low luminance. Statistically, the average luminance and power consumption of the luminous bodies 2912, 2916, 2922, and 2926 in the backlight structure as shown in FIG. 29 are less than the average luminance and power consumption of the luminous bodies in the backlight 2800 having the structure shown in FIG. . In addition, the image quality is improved even compared to the backlight 2700 of FIG. 27.

Increasing the number of segments in the same way improves the power consumption and image quality statistically. 30 is a plan view showing another novel segmented backlight assembly. Referring to FIG. 30, the backlight 3000 includes a matrix of light guide plates overlapping each other. In an embodiment of the present invention, each quadrant includes a matrix of light guide plates that are independent of each other. Some of the light guide plates 3020 are interlocked with the light-emitting bodies 3022 arranged in a column direction, and the other light guide plates 3010 are interlocked with the light-emitting bodies 3012 arranged in a row direction.

In this embodiment, when the resolution of the backlight is N x M, (N + M) light guide plates and light emitters are used as shown in FIG. 30. The (N + M) light guide plates and light emitters correspond to two columns (eg, left and right sides of the backlight 3000) and two rows (eg, upper and lower sides of the backlight 3000). As another embodiment, another structure using N + M light guide plates and light emitters to implement a resolution of N x M in a backlight may be considered. That is, illuminants are arranged in only one column (for example, one of the left and right sides of the backlight) and one row (for example, one of the upper and lower sides of the backlight), and the light guide plates are also arranged in one column and one row. Applicable only to The number of the matrix in which the row and the column intersect is the embodiment of applying the light guide plates and light emitters to the two columns and two rows described above, and the embodiment of applying the light guide plates and light emitters to only one column and one row. They are the same as each other in the example, but the number of light guide plates and light emitters used is reduced. Therefore, the manufacturing cost of the backlight can be reduced. However, in the case of applying the light guide plates and light emitters to only one column and one row, the statistical advantage is reduced, so that power consumption is reduced compared to the conventional backlight. It is reduced compared to the case of applying light guide plates and light-emitting bodies to the field. In addition, as described above, the light emitters 3022 may be white or a combination of one or more color light emitters. Various embodiments of the backlight to which the above-described method is applied are possible.

31 is a cross-sectional view showing a light guide plate of a new segmented backlight assembly. Referring to FIG. 31, a cross-sectional view of a backlight 3100 in which a plurality of light guide plates 3120 in a column direction are disposed on a light guide plate 3110 in a row direction is disclosed. In the cross-sectional view of the backlight 3100, a light ray beam 3130 is trapped inside the light guide plate 3110 by total reflection occurring inside the light guide plate 3110. A part of the light beam 3130 trapped inside the light guide plate 3110 is diffused and refracted by a feature 3140 formed on one surface of the light guide plate 3110 to become a diffuse light 3135, and the light guide plate 3110 It is emitted outside of. In the same way, the diffused light 3135 emitted from the light guide plate 3110 in the row direction is diffused and refracted inside the light guide plates 3120 in the column direction, and is emitted to the outside of the light guide plates 3120 in the column direction. During driving, when the light guide plates are illuminated with the maximum luminance, the sum of the light diffused from the light guide plates 3110 in the row direction and the light guide plates 3120 in the column direction represents the maximum luminance. When the light guide plates 3110 in the row direction and the light guide plates 3120 in the column direction are not all illuminated, light does not exist at a point where the light guide plates intersect. When only the light guide plate in one direction among the light guide plates 3110 in the row direction and the light guide plates 3120 in the column direction is illuminated, and the light guide plate in the other direction is not illuminated, the luminance depends on the degree of the illuminated light guide plate. It has a low value. Accordingly, in the case of the aforementioned N x M backlight, a very high degree of crosstalk occurs in the row direction and the column direction.

The segment backlight having a very high crosstalk described above can be applied to various display systems. 32A and 32B show that a single color panel and a color panel are disposed on the front side of the segmented backlight, respectively. FIG. 32A is a block diagram showing a new segmented backlight combined with a single color panel disposed on the front side, and FIG. 32B is a block diagram showing a new segmented backlight combined with a multi-primary color panel disposed on the front side. Referring to FIG. 32A, a display system 3200 using a segment backlight 3220 includes a transmissive spatial light modulator 3260 such as a monochromatic LCD. For example, the spatial light modulator 3260 has a higher resolution than the backlight 3220. As another embodiment, the spatial light control unit may have the same resolution as the backlight, or may have a lower resolution.

During driving, the display system 3200 may receive an input image data stream such as detectable data, gamma data, and digitally quantized R*G*B* image data. A gamma block (gamma function) 3205 linearizes the input data. A linear RGB signal is irradiated by a peak function block 3210 to find peak luminance values in pixels. The pixels are disposed in an area illuminated by rows and columns of the backlight 3220. For example, the light emitters 3220 may have various spectra like white light. The RGB values irradiate a maximum red value, a maximum green value, or a maximum blue value, and are mapped to corresponding columns and rows, respectively.

In another embodiment, the illuminants have independently driven primary colors. The primary colors of the light emitters may include red, green, and blue. In this case, RGB values are independently mapped in each column and row. An image rendered in a predetermined frame is first analyzed before values corresponding to intensity are distributed to each color illuminant, and there are certain degrees of freedom and constraints to be considered at this time. For example, when the maximum value for the red color in the M-th row has a medium intensity, the maximum value for the red color is dispersed by the light guide plates that are orthogonal to each other by the S-th column crossing the M-th row. do. That is, the maximum value for the red color of the image corresponding to the M-th row and the S-th column can be obtained by summing the light generated by the red light-emitting body corresponding to the M-th row and the red light-emitting body corresponding to the S-th column.

For example, in assigning values of intensity for each color, the intensity of red for each column (S) and row (M) at the intersections (e.g., (M, S)) is independently determined. The values of the intensity of the illuminant are assigned to have an intensity sufficient to represent. Accordingly, it is possible to limit the amount of red light provided to the panel disposed in front to have an appropriate level. However, even if the above-described method is used, it cannot be viewed as being optimized in terms of power consumption. As another embodiment, all of the red light may be assigned to one illuminant to reduce the burden of other illuminants. In this case, red light may be allocated to one red light emitter in both the row direction and the column direction. In this way, second order statistics can be applied. For example, in the case where red light at the coordinates of (M, S) in the matrix of light guide plates has a medium intensity and has a maximum value among light guide plates belonging to the S-th column, selectable possibility of red intensity using two red light emitters Is affected by the intensity of the second red value among the intensities of the red emitters corresponding to the M-th column and the S-th row. The choice of the intensity value of the color illuminants can be determined through various optimization schemes. Various variables such as power consumption may be considered in the optimization process.

In determining the intensity values of the color luminous body for a space in which an image is displayed, a temporal determination may be considered together, or a spatial determination or an independent determination of only a temporal determination may be possible. For example, the backlight may be illuminated by scanning along rows or columns for predetermined illumination. As another embodiment, the light emitters corresponding to the columns may have a dark state one column at a time for a very short time, thereby reducing power consumption. Darkening each column in this way may be performed in a certain order or may be performed in an irregular order. For example, in the case where each column has a dark state, the backlight may be darkened in order from top to bottom or bottom to top. In a similar manner, in order to have a dark state one row at a time, the backlight may be darkened sequentially for each row from left to right or from right to left. The scanning order as described above may be linked to an address scanning direction of pixels of a spatial light control unit such as an LCD illuminated by a backlight. Thus, it can have a desired transmittance value before it is illuminated.

Referring again to FIGS. 32A and 32B, the output of the peak function block 3210 may be an encoded down sampled image in a matrix form. The down-sampled image encoded in the matrix form is indicated by a downward arrow. After the peak values are transmitted to the backlight control unit 3212, they are transmitted to the light emitters 3222 of the backlight 3220. Also, the peak values may be transmitted to the backlight interpolation block 3205. The backlight interpolation block 3205 calculates a degree of illumination under each pixel displaying an image, and renders the peak values to be applied to the spatial light controller 3260. Through the above calculation, it is possible to construct a theoretical model for illumination of the backlight based on the image data values. As another embodiment, the calculation may be performed using empirical data of illumination values measured according to image data values.

The output of the backlight interpolation block 3205 may be an upsampled image corresponding to the illumination XL by the backlight 3220, and the upsampled image is indicated by an upward arrow. Thereafter, the X/XL block 3236 divides the linear RGB image values X by the interpolated backlight illumination values XL. Subsequently, a gamma (i-1) correction block (Gamma Correction blick) 3215 quantizes the X/XL values by gamma correction to obtain a gamma value of the display unit. An image X to be displayed is configured by convolving (convolved or interlocking) with the illumination value XL of the backlight 3220 and the X/XL value of the image in the spatial light adjusting unit 3260.

The backlight having the matrix structure described above improves the performance of a rendered subpixel rendered RGBW (RGBW) display system or a multi-primary color display system having various structures. Referring to FIG. 32B, in a display system 3201 using a segment backlight 3220, a transmissive multi-primary color (eg, RGBW, RGBC, RGBY, etc.) color filter 3265 is formed using a segment backlight 3220. A spatial light control unit 3260 is shown. For example, the spatial light control unit 3260 of FIG. 32B may be an LCD having various types of layouts described above or according to the prior art cited by the present invention. The gamma block (Gamma function) 3205 linearizes the input gamma and digitally quantized R*G*B* images (incoming perceptually, gamma, digitally quantized R*B*B* images). A peak function block 3210 irradiates the linearized RGB signal and is illuminated by the matrix backlight 3220 and is mapped to the rows and columns of the matrix backlight 3220. brightness values). For example, in the case of the light emitters 3222 having a wide spectrum such as a white light source, the RGB values have a maximum red value, a maximum green value, or a maximum blue value in each column and each row in the aforementioned backlights. In the case of the light emitters 3222 having independently driven primary colors such as red, green, and blue, the RGB values are independently of each other in each column and each row of the backlights. The blue value is investigated. The output value of the peak function block 3210 includes a matrix encoded down sampled image, and is indicated by a downward arrow in the drawing. The maximum values (eg, a maximum red value, a maximum green value, and a maximum blue value) are transmitted to the backlight controller 3212 and then applied to the light emitters 3222 of the backlight 3220. The maximum values are also sent to the Backlight Interpolation block 3205. The backlight interpolation block 3205 calculates the intensity of illumination from each pixel of the image, and the calculated value is rendered by the spatial light control unit 3260.

The output value of the backlight interpolation block 3205 is an upsampled image and may be indicated by an upward arrow indicating the illumination value XL of the backlight 3220. Linear RGB image values (X) are divided by interpolated backlight illumination values (XL) by an X/XL block 3236. Subsequently, the color space mapping (GMA) block 3240 converts the RGB X/XL image into an RGBW X/XL image using an appropriate GMA method. Thereafter, the RGBW X/XL image is subjected to a subpixel rendering process through one of the above-described methods. The RGBW X/XL image that has undergone the subpixel rendering process is converted to fit the gamma value of the displayed image through a gamma correction quantized process by a gamma (i-1) correction block 3215. The luminance value XL of the backlight 3220 is convolved with the RGBW X/XL image subpixel rendered by the spatial light control unit 3260, and the image to be displayed (X ).

The matrix backlight may improve performance of field sequential color systems. 33 is a block diagram illustrating a display system having a new segmented backlight to which a system and method for continuous control of a mixed virtual primary color space is applied. Referring to a block diagram 3300 of a display system using a segment backlight 3320 illustrated in FIG. 33, a transmissive spatial light modulator 3360 is illuminated by the segment backlight 3320. (illuminated). The input gamma block 3305 may linearize input image data such as input detectable data, gamma data, and digitally quantized R*G*B* image data. A linear RGB signal is irradiated by a bounding box block 3330 to find the smallest box covering color and luminance values in pixels. In this case, the irradiation process of the bounding box block 3330 is performed on pixels mapped in an area illuminated by rows and columns of the backlight 3320. The values obtained from the bounding box block 3330 are used to calculate a set of virtual primary colors of a Calc Virtual Primaries block 3332. The virtual primary color values are used to control the field continuous color luminance values of the light emitters 3322 of the segment backlight 3320 by the field continuous color (FSC) block 3325. The light emitters may include red, green, blue LEDs, red, green, blue, bluish green (emerald green) LEDs, or other various combinations of color emitters. In addition, color and luminance values of the light emitters 3320 are input to the backlight interpolation block 3334, and illumination values corresponding to each pixel of the image are calculated. Illumination values corresponding to each pixel calculated by the backlight interpolation block 3334 are rendered by the spatial light control unit 3360.

The output value of the backlight interpolation block 3334 may be an upsampled image, and the upsampled image is indicated by an upward arrow. The ㆇ value calculation block 3340 calculates the ㆇ value by rendering the interpolated luminance values and linear RGB values. The ㆇ value is relative transmission values and is convolved with backlight luminance values in each color field. Thereafter, the convolved ㆇ values are summed and rendered for a predetermined color, and then displayed as an image. The ㆇ values are gamma corrected and quantized by the output gamma block 3315. In this case, the gamma corrected and quantized processes are quantized by an electro-optical transfer function to suit the transmissive spatial light control unit 3360.

For example, suppose you watch a black and white movie on a television with a color station icon in one corner. Among the columns and rows of the matrix backlight 3320, most of the columns and rows include primary colors having various levels of grayscale. Columns and rows intersecting each other at a point where the icon is located may include primary colors having a larger color gamut. At the intersection point, the size of the color space may have a maximum value. At a point where the columns and rows intersect, they are illuminated by the levels of grayscales obtained by linearly mixing virtual primary colors of a wide color space. Therefore, virtual primary colors of pale colors with a reduced color gamut spread are formed. The backlight interpolation block 3334 detects the above-described phenomenon, and the ㆇ value calculation block 3340 compensates for the phenomenon detected by the backlight interpolation block 3334. Therefore, even if a black-and-white image is displayed, an original full color icon without color deterioration may be displayed at one corner of the image, and color break-up in the rendered image. Is reduced.

The methods and operations disclosed by the above-described embodiments include digital electric circuitry including the above-described structures, structural equivalents and combinations thereof, computer software, firmware, Or it can be implemented by hardware. Embodiments of the present invention include one or more computer program results, that is, computer program modules encoded to be executed in one or more computer-readable media, or a computer that controls the operation of a data processing device. It can be implemented with lute program modules.

Computer programs (programs, software, software applications, scripts, code, etc.) can be written in various types of programming languages such as compiled or interpreted languages. The computer program includes a stand-alone program, a module type program, a component type program, a subroutine type program, or a program operating in various types of computer environments. It can be implemented in a form. The computer program may have the form of a file in the file system of the computer, but as another embodiment, it may have various forms other than the file form. The program is implemented as a file or part of data of other programs (for example, one or more scripts stored in a markup language document), implemented as a single file on the program, or multiple common It may be implemented as multiple coordinated files (eg, one or more modules, sub-programs, or part of code). The computer program may be executed on one computer or may be executed on a plurality of computers. When a program is executed on a plurality of computers, the plurality of computers may be gathered in one place, or may be disposed in a plurality of places separated from each other and connected to each other through a communication network.

The flow of processes and logic disclosed in the embodiments of the present invention may be performed by one or more programmable processors. The processors are executed by one or more computer programs and driven by input data to generate output values. The flow of the processes and logic can be implemented through a logic circuit with a special purpose. For example, the special purpose logic circuit may include a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

Processors for executing a computer program may use a general microprocessor or a special purpose microprocessor, and one or more processors having various types of digital computer types may be used. In general, a processor receives data and instructions from read-only memory (ROM), random access memory (RAM), or a combination thereof. The core components of a computer include a processor that performs instructions and one or more memory devices that store instructions and data. The computer can be applied to other devices such as the above-described display devices, mobile telephones, personal digital assistants (PDAs), portable audio players, and Global Positioning System (GPS) receivers. Storage devices that can be read from a computer and store instructions and data include non-volatile memories, media, and the like. For example, the memory device may be an erasable programmable read only memory (EPROM), an electrically erasable and programmable read only memory (EEPROM), a flash memory device, a magnetic disk, an internal hard disk, a removable disk. (removable disks), magneto-optical disks, compact disc read only memory (CD-ROM) disks, digital versatile disc-read only memory (DVD-ROM) disks, etc. . The processor and memory device (or memory) may be configured or assisted by special purpose logic circuits.

According to the image display method of the present invention, an array of luminous bodies such as light emitting diodes (LEDs) is used as a backlight of a display system having sub-pixels, and can be filtered to have higher color purity in image display compared to the prior art. have. However, in certain types of display panels (eg, liquid crystal display devices), the contrast ratio is limited, and thus bleed of color may occur compared to the off state of the sub-pixels. In addition, since the color filter itself does not have a high color purity, it is possible to unnecessarily transmit a part of colors generated by other color light-emitting bodies. In the display system of the present invention, individual luminous bodies arranged in the backlight array are independently addressed, and it is possible to more precisely control the color of the backlight. That is, the individual light emitters can be independently controlled to independently control the color of the backlight. The ability to independently control the color of the backlight increases the degree of freedom by increasing the color purity of the display device and an active driving area. In the case of sub-pixel rendering in sub-pixels of the display panel by optimizing the overall or local spread of luminance information of light emitted from the backlight array and having a constant color temperature Increases the efficiency of sub-pixel rendering.

Accordingly, by selecting a color value of the backlight to display an image, the image quality of the display device is improved, color reproducibility is increased, power consumption is reduced, and luminance is improved.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (16)

A display panel having subpixels having respective colors to be displayed, and individually addressable to supply light to the subpixels of the display panel and including light emitters having respective colors, the display panel In a display system having a backlight for receiving image data corresponding to an image displayed on, in an image display method for displaying an image,
Determining subpixel color values corresponding to color values transmitted by each of the subpixels for displaying the image, from the image data;
Determining backlight values corresponding to brightness of the light emitters for displaying the image from the image data;
Determining a portion of the subpixel color values and a portion of the backlight values entirely corresponding to any one of saturated yellow and near-saturated yellow of the image data;
Adjusting the backlight values to increase the amount of yellow light emitted by the light emitters of the backlight; And
Adjusting the color values to reduce an amount of yellow light transmitted by the subpixels of the display panel,
The saturated yellow and the yellow close to the saturation are yellow adjacent to a white area. The method of claim 1, further comprising displaying the image using the adjusted backlight values and the adjusted color values. The method of claim 1, wherein the amount of yellow light added by adjusting the backlight values is at least approximately equal to the amount of yellow light reduced by adjusting the color values. The method of claim 1, wherein adjusting the backlight values
Increasing an amount of red light emitted by red light emitters among the light emitters of the backlight; And
And increasing an amount of green light emitted by green light emitters among the light emitters of the backlight. The method of claim 4, wherein adjusting the color values
Reducing an amount of red light transmitted by the red sub-pixels of the sub-pixels of the display panel; And
And reducing an amount of green light transmitted by green subpixels of the subpixels of the display panel. The method of claim 1, wherein adjusting the backlight values
And increasing the amount of yellow light to increase the amount of yellow light transmitted through the white sub-pixels of the sub-pixels of the display panel. The method of claim 1, wherein the luminous bodies include multi-primary color luminous bodies. 8. The method of claim 7, wherein the luminous bodies include red luminous bodies, green luminous bodies, blue luminous bodies, and white luminous bodies. A display panel having subpixels and white subpixels having respective colors to be displayed, and individually addressable to supply light to the subpixels of the display panel and emitters having respective colors are included. And, in a display system including a backlight for receiving image data corresponding to the image displayed on the display panel, in the method for removing a simultaneous contrast error,
Detecting any one of a region having a saturated color and a region having a color close to saturation in the image;
Increasing the amount of the color emitted by the light emitters of the backlight to increase the amount of the color transmitted by the white subpixels of the display panel; And
Reducing the amount of the color transmitted by the subpixels of the display panel to compensate for the increased amount of the color transmitted by the white subpixels of the display panel,
And the area having a saturated color and the area having a color close to the saturation are areas adjacent to a white area. The method of claim 9, further comprising displaying the image after the increasing and decreasing steps. 10. The method of claim 9, wherein the amount of the color added by the increasing step is at least approximately equal to the amount of the color reduced by the reducing step. The method of claim 9, wherein the color is yellow. The method of claim 12, wherein the step of increasing
Increasing an amount of red light emitted by red light emitters among the light emitters of the backlight; And
And increasing an amount of green light emitted by green light emitters among the light emitters of the backlight. The method of claim 13, wherein the step of reducing
Reducing an amount of red light transmitted by red subpixels of the subpixels of the display panel; And
And reducing an amount of green light transmitted by green subpixels of the subpixels of the display panel. The method of claim 9, wherein the luminous bodies include multi-primary color luminous bodies. The method of claim 15, wherein the luminous bodies include a red luminous body, a green luminous body, a blue luminous body, and a white luminous body.

Images