Display device, display control method, and program

Abstract

The present technology relates to a display device, a display control method, and a program that allow a reduction in power consumption, while maintaining natural display of an image. In the present invention, a color gamut determination unit determines whether or not the chromaticity of a pixel exceeds a reference color gamut, which is a color gamut serving as a reference, on the basis of the chromaticity of the pixel. A multiplication unit multiplies the Y signal of the pixel by a gain smaller than 1 when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut. The display of the pixel is controlled on the basis of the Y signal obtained as a result of the multiplication by the multiplication unit and the Cb signal and Cr signal of the pixel. The present technology can be applied to, for example, a television receiver having a display unit such as an LCD display, a mini-LED display, an LED display, or an OLED display.

Description

Display device, display control method, and program

[0001] This technology relates to a display device, a display control method, and a program, and more particularly to a display device, a display control method, and a program that can suppress power consumption while maintaining the display of natural images.

[0002] In recent years, people's concern for the environment has increased, and there is a demand for reducing the power consumption of electronic devices. However, with flat panel displays, power consumption is increasing as brightness increases.

[0003] Therefore, a display device has been devised that reduces power consumption while maintaining brightness by utilizing the Helmholtz-Kohlrausch effect (HK effect) to decrease the luminance value and increase the saturation value (see, for example, Patent Document 1). The HK effect is a visual effect in which, even with the same luminance, the higher the saturation (the deeper the chromaticity), the brighter it appears.

[0004] Some display devices that take the HK effect into consideration suppress changes in perceived brightness by increasing the brightness of the input color when converting the input color by reducing the saturation of the input color, taking the HK effect into account (see, for example, Patent Document 2).

[0005] Japanese Patent Publication No. 2014-59563 Japanese Patent Publication No. 2017-76955

[0006] However, no method had been considered for reducing power consumption while maintaining natural image display in display devices.

[0007] This technology was developed in light of these circumstances, and aims to reduce power consumption while maintaining the display of natural images.

[0008] One aspect of this technology is a display device comprising: a color gamut determination unit that determines whether the chromaticity of a pixel exceeds a reference color gamut, which is a reference color gamut, based on the chromaticity of the pixel; a multiplication unit that multiplies the luminance signal of the pixel by a gain of less than 1 if the color gamut determination unit determines that the chromaticity exceeds the reference color gamut; and a display control unit that controls the display of the pixel based on the luminance signal obtained as a result of multiplication by the multiplication unit and the color difference signal of the pixel.

[0009] One aspect of this technology is a display control method in which a display device determines, based on the chromaticity of a pixel, whether the chromaticity of the pixel exceeds a reference color gamut, if it is determined that the chromaticity exceeds the reference color gamut, multiplies the luminance signal of the pixel by a gain less than 1, and controls the display of the pixel based on the luminance signal and the color difference signal of the pixel obtained as a result of the multiplication.

[0010] One aspect of this technology is a program that causes a computer to function as a display control unit that controls the display of a pixel based on the chromaticity of the pixel, which includes a color gamut determination unit that determines whether the chromaticity of the pixel exceeds a reference color gamut, which is a reference color gamut, a multiplication unit that multiplies the brightness signal of the pixel by a gain of less than 1 if the color gamut determination unit determines that the chromaticity exceeds the reference color gamut, and the brightness signal and the color difference signal of the pixel obtained as a result of the multiplication by the multiplication unit.

[0011] In one aspect of this technology, it is determined whether the chromaticity of a pixel exceeds a reference color gamut, and if it is determined that the chromaticity exceeds the reference color gamut, a gain less than 1 is multiplied by the luminance signal of the pixel, and the display of the pixel is controlled based on the luminance signal obtained as a result of the multiplication and the color difference signal of the pixel.

[0012] The display device may be a standalone device or a module incorporated into another device.

[0013] This is a u'v' chromaticity diagram showing an example of a color gamut. This is a table showing an example of the increase in brightness due to the HK effect. This is a block diagram showing an example configuration of one embodiment of a television receiver to which this technology is applied. This is a block diagram showing an example configuration of the gain multiplication unit in Figure 3. This is a u'v' chromaticity diagram showing an example of a color gamut to be classified. This is a u'v' chromaticity diagram showing an example of a color to be classified. This is a diagram showing an example of the coordinate position of each point on the u'v' chromaticity diagram in Figure 6. This is a diagram explaining the classification process. This is another diagram explaining the classification process. This is a diagram showing a first example of a gain map. This is a diagram explaining how to set the gain of high-gamut pixels. This is a diagram explaining how to set the gain of low-gamut pixels. This is a diagram showing an overview of the relationship between the gain set by the gain setting unit and u'v' chromaticity. This is a diagram showing an overview of the relationship between the gain and u'v' chromaticity when the gain is set to 1 regardless of chromaticity. This is a flowchart explaining the display control process. This is a flowchart explaining the gain setting process. This is a diagram showing an example of the range of gain registered in the gain map. This is a diagram showing another example of the range of gain registered in the gain map. This is a block diagram showing an example configuration of computer hardware.

[0014] The following describes the embodiments for implementing this technology. The explanation will be given in the following order: 1. Explanation of the HK effect 2. One embodiment 3. Computer

[0015] <1. Explanation of the HK effect> <Example of color gamut> Figure 1 is a u'v' chromaticity diagram showing an example of a color gamut.

[0016] The u'v' chromaticity diagram is a UCS (Uniform Chromaticity Scale) chromaticity diagram established by the CIE (International Commission on Illumination) in 1976. The u'v' chromaticity diagram is one of the chromaticity diagrams that emphasizes the visual uniformity of colors, and is designed in particular to make the visual distance between different colors more uniform. The u'v' chromaticity diagram was developed to improve upon the non-uniformity of the CIE 1931 chromaticity diagram and is characterized by its ability to more accurately evaluate color differences. The relationship between u',v' in the u'v' chromaticity diagram and x,y in the CIE 1931 chromaticity diagram is expressed by the following equation (0).

[0017] u´=4x / (-2x+12y+3) v´=9y / (-2x+12y+3)・・・(0)

[0018] As shown in Figure 1, the color gamut 11 is represented by a triangle with vertices R representing red, G representing green, and B representing blue. The color gamut 12 is represented by a triangle with vertices R' representing red, G' representing green, and B' representing blue. The color gamut 12 is wider than the color gamut 11 by Δu'v'. Specifically, the distance between each of points R, G, and B and each of points R', G', and B' is Δu'v'.

[0019] <Examples of Brightness Increase Due to HK Effect> Figure 2 is a table showing examples of the increase in brightness (perceived brightness) of red, green, and blue in color gamut 12 relative to color gamut 11 due to the HK effect, when Δu'v' in Figure 1 is 0.01.

[0020] Specifically, the first column of the table in Figure 2 lists each color, and the second column lists the increase in brightness corresponding to that color. As shown in Figure 2, when Δu'v' is 0.01, the brightness increases by 13% when the red color represented by point R changes to the red color represented by point R'. The brightness increases by 8% when the green color represented by point G changes to the green color represented by point G'. The brightness increases by 24% when the blue color represented by point B changes to the blue color represented by point B'.

[0021] As described above, due to the HK effect, even with the same luminance (e.g., 100 nits), brightness increases as the chromaticity deepens. Therefore, this technology utilizes this HK effect to reduce luminance in the wide color gamut region, thereby suppressing power consumption while maintaining the display of natural images.

[0022] <2. One Embodiment> Figure 3 is a block diagram showing an example of the configuration of one embodiment of a television receiver to which this technology is applied.

[0023] The television receiver 30 in Figure 3 comprises an image acquisition unit 31, a compensation processing unit 32, an RGB / YCbCr conversion unit 33, a saturation adjustment unit 34, a brightness adjustment unit 35, a gain multiplication unit 36, a YCbCr / RGB conversion unit 37, a display control unit 38, and a display unit 39. The television receiver 30 displays based on the RGB signals of each pixel of the television broadcast image acquired from a tuner (not shown).

[0024] Specifically, the video acquisition unit 31 acquires the RGB signals of each pixel of the television broadcast video from a tuner (not shown) and supplies them to the compensation processing unit 32. The compensation processing unit 32 performs various compensation processes on the RGB signals of each pixel supplied from the video acquisition unit 31 and supplies them to the RGB / YCbCr conversion unit 33. The RGB / YCbCr conversion unit 33 converts the RGB signals of each pixel supplied from the compensation processing unit 32 into YCbCr signals. The compensation processing unit 32 supplies the Cb and Cr signals of the YCbCr signal to the saturation adjustment unit 34 and the Y signal to the brightness adjustment unit 35.

[0025] The saturation adjustment unit 34 performs a saturation adjustment process on the Cb signal and Cr signal of each pixel supplied from the RGB / YCbCr conversion unit 33 to adjust the saturation, and supplies the resulting Cb signal and Cr signal to the gain multiplication unit 36. The brightness adjustment unit 35 performs a brightness adjustment process on the Y signal of each pixel supplied from the RGB / YCbCr conversion unit 33 to adjust the brightness, and supplies the resulting Y signal to the gain multiplication unit 36.

[0026] The gain multiplication unit 36 ​​determines, for each pixel, whether the chromaticity of that pixel exceeds the reference color gamut, which is a reference color gamut, based on the Cb and Cr signals from the saturation adjustment unit 34 and the Y signal from the brightness adjustment unit 35. The reference color gamut is, for example, 75% of the color gamut called BT.2020.

[0027] The gain multiplication unit 36 ​​multiplies the Y signals of pixels whose chromaticity is determined to exceed the reference color gamut, from the Y signals of each pixel supplied by the brightness adjustment unit 35, by a gain of less than 1, while leaving the Y signals of pixels whose chromaticity is determined not to exceed the reference color gamut unchanged. The gain multiplication unit 36 ​​then supplies the YCbCr signal for each pixel, which consists of the resulting Y signal and the Cb and Cr signals of each pixel supplied by the saturation adjustment unit 34, to the YCbCr / RGB conversion unit 37.

[0028] The YCbCr / RGB conversion unit 37 converts the YCbCr signal from each pixel supplied by the gain multiplication unit 36 ​​into an RGB signal and supplies it to the display control unit 38. The display control unit 38 controls the display of the display unit 39 based on the RGB signal from each pixel supplied by the YCbCr / RGB conversion unit 37, and displays an image on the display unit 39.

[0029] The display unit 39 has a wider color gamut than BT.2020. The display unit 39 is composed of an LCD (Liquid Crystal Display) display, a mini-LED (Light Emitting Diode) display, an LED display, etc. The display unit 39 may also be composed of an OLED display such as a QD-OLED (Quantum Dot OLED (Organic Light Emitting Diode)) display or a W-OLED (White OLED) display. The display unit 39 may also be composed of a laser display. The display unit 39 displays images under the control of the display control unit 38.

[0030] The video acquisition unit 31 may acquire the RGB signal of the video for video distribution from a communication unit that communicates via a wired or wireless transmission medium, rather than the RGB signal of the video for television broadcasting. In this case, the video for video distribution is displayed on the display unit 39 based on that RGB signal.

[0031] Since this technology relates to video, the diagram and explanation of the audio-related block of the television receiver 30 will be omitted. However, the television receiver 30 also has a configuration that acquires audio signals from television broadcasts and outputs that audio.

[0032] <Example of Gain Multiplication Unit Configuration> Figure 4 is a block diagram showing an example of the configuration of the gain multiplication unit 36 ​​in Figure 3.

[0033] The gain multiplication unit 36 ​​in Figure 4 is composed of a chromaticity conversion unit 51, a color gamut determination unit 52, a classification unit 53, a gain storage unit 54, a gain setting unit 55, and a multiplication unit 56. The YCbCr signal of each pixel, which consists of the Cb signal and Cr signal (chrominance signal) of each pixel from the saturation adjustment unit 34 in Figure 3 and the Y signal of each pixel from the brightness adjustment unit 35, is input to the chromaticity conversion unit 51 and the multiplication unit 56.

[0034] The chromaticity conversion unit 51 converts the YCbCr signal of each input pixel into chromaticity coordinates (u',v') in the u'v' chromaticity diagram. The chromaticity conversion unit 51 supplies the chromaticity coordinates (u',v') of each pixel to the color gamut determination unit 52.

[0035] The color gamut determination unit 52 determines, for each pixel, whether the chromaticity coordinates (u',v') of that pixel are outside the reference color gamut, that is, whether the chromaticity exceeds the reference color gamut, based on the chromaticity coordinates (u',v') of each pixel supplied from the chromaticity conversion unit 51. The color gamut determination unit 52 supplies the chromaticity coordinates (u',v') of high-gamut pixels, which are pixels determined to be outside the reference color gamut, to the classification unit 53. The color gamut determination unit 52 supplies the determination results of low-gamut pixels, which are pixels determined not to be outside the reference color gamut, to the gain setting unit 55.

[0036] The classification unit 53 performs classification processing on high-gamut pixels based on the chromaticity coordinates (u',v') of the high-gamut pixels supplied by the color gamut determination unit 52. Classification processing is the process of determining which of the multiple color gamuts the chromaticity coordinates (u',v') belong to, and which of the multiple colors within that color gamut it belongs to. Based on the classification processing, the classification unit 53 supplies classification information representing the color gamut and color to which the chromaticity coordinates (u',v') of the high-gamut pixels belong to to the gain setting unit 55.

[0037] The gain storage unit 54 stores a gain map that associates the gain with each of the multiple color gamuts and each of the multiple colors into which the chromaticity coordinates (u',v') of high-gamut pixels are classified during the classification process. This gain is a value less than 1 and is set for each of the multiple color gamuts and each of the multiple colors into which the chromaticity coordinates (u',v') of high-gamut pixels are classified during the classification process.

[0038] Based on the classification information of high-gamut pixels supplied from the classification unit 53, the gain setting unit 55 reads the gain registered in the gain map corresponding to the color gamut and color represented by the classification information from the gain storage unit 54 and sets it as the gain of the high-gamut pixel. Based on the determination result of the low-gamut pixel supplied from the color gamut determination unit 52, the gain setting unit 55 sets the gain of the low-gamut pixel to 1. The gain setting unit 55 supplies the gain of each pixel set in this manner to the multiplication unit 56.

[0039] The multiplication unit 56 multiplies the Y signal (luminance signal) of the YCbCr signal of each input pixel by the gain of that pixel, which is supplied from the gain setting unit 55. The multiplication unit 56 then supplies the resulting YCbCr signal to the YCbCr / RGB conversion unit 37 in Figure 3.

[0040] <Examples of Classified Color Gamuts> Figure 5 is a u'v' chromaticity diagram showing examples of color gamuts in which the chromaticity coordinates (u',v') of high-gamut pixels are classified during the classification process.

[0041] As shown in Figure 5, seven color gamuts, Zones 1 to 7, which are wider than the reference color gamut Zone 0, are set as the color gamuts into which the chromaticity coordinates (u',v') are classified. In this embodiment, the number of color gamuts into which the chromaticity coordinates (u',v') are classified is seven, but it can be any integer of 1 or more.

[0042] <Examples of classified colors> Figure 6 is a u'v' chromaticity diagram showing examples of colors to which the chromaticity coordinates (u',v') of a high-gamut pixel are further classified within the color gamut to which they belong after classification processing.

[0043] As shown in FIG. 6, the color gamut 71 determined to belong to the chromaticity coordinates (u′, v′) has a triangular shape with vertices at the point R representing red, the point G representing green, and the point B representing blue. This color gamut 71 is further divided into six colors: red, green, blue, cyan, magenta, and yellow.

[0044] Specifically, the line segment RR connecting the point R and the point R G and the line segment RR connecting the point R and the point R G are used for the classification of red in the color gamut 71. Note that the point R B is a point on the line segment RG connecting the point R and the point G, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point R, that is, at a distance of 2 / 3 times the length L from the point G. The point R B is a point on the line segment RB connecting the point R and the point B, and is located at a distance of 1 / 3 times the length L of the line segment RB from the point R, that is, at a distance of 2 / 3 times the length L from the point B. G is a point on the line segment RG connecting the point R and the point G, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point R, that is, at a distance of 2 / 3 times the length L from the point G. The point R RG is a point on the line segment RG connecting the point R and the point G, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point R, that is, at a distance of 2 / 3 times the length L from the point G. The point R RG is a point on the line segment RG connecting the point R and the point G, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point R, that is, at a distance of 2 / 3 times the length L from the point G. The point R B is a point on the line segment RB connecting the point R and the point B, and is located at a distance of 1 / 3 times the length L of the line segment RB from the point R, that is, at a distance of 2 / 3 times the length L from the point B. RB is a point on the line segment RB connecting the point R and the point B, and is located at a distance of 1 / 3 times the length L of the line segment RB from the point R, that is, at a distance of 2 / 3 times the length L from the point B. RB is a point on the line segment RB connecting the point R and the point B, and is located at a distance of 1 / 3 times the length L of the line segment RB from the point R, that is, at a distance of 2 / 3 times the length L from the point B.

[0045] The line segment GG connecting the point G and the point G R and the line segment GG connecting the point G and the point G R are used for the classification of green in the color gamut 71. Note that the point G B is a point on the line segment RG, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point G, that is, at a distance of 2 / 3 times the length L from the point R. The point G B is a point on the line segment RG, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point G, that is, at a distance of 2 / 3 times the length L from the point R. The point G R is a point on the line segment RG, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point G, that is, at a distance of 2 / 3 times the length L from the point R. The point G RG is a point on the line segment RG, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point G, that is, at a distance of 2 / 3 times the length L from the point R. The point G RG is a point on the line segment RG, and is located at a distance of 1 / 3 times the length L of the line segment RG from the point G, that is, at a distance of 2 / 3 times the length L from the point R. The point G B is a point on the line segment GB connecting the point G and the point B, and is located at a distance of the length L of the line segment GB from the point G [[ID=....]] GB is a point on the line segment GB connecting the point G and the point B, and is located at a distance of the length L of the line segment GB from the point G GB is a point on the line segment GB connecting the point G and the point B, and is located at a distance of the length L of the line segment GB from the point G

[0046] The line segment BB connecting the point B and the point B G and the line segment BB connecting the point B and the point B G are used for the classification of blue in the color gamut 71. Note that the point B R is a point on the line segment GB, and is located at a distance of 1 / 3 times the length L of the line segment GB from the point B, that is, at a distance of 2 / 3 times the length L from the point G. R [[ID=.....]] G is a point on the line segment GB, and is located at a distance of 1 / 3 times the length L of the line segment GB from the point B, that is, at a distance of 2 / 3 times the length L from the point G. GB of 1 / 3 times the length L from the point B, that is, at a distance of 2 / 3 times the length L from the point G.GB Point B is a point located 2 / 3 times the distance from point B. R This is the line segment RB from point B to L RB A point that is 1 / 3 the distance from point R, i.e., a distance L from point R. RB It is a point that is 2 / 3 times the distance from that point.

[0047] Point G B and point B G Line segment G connecting the points B B G However, it is used to classify cyan within the 71-color gamut. Point B R and point R B However, it is used to classify magenta within the 71-color gamut. Point G R and point R G However, it is used to classify yellow within the 71-color gamut.

[0048] In this embodiment, the number of colors to which the color gamut 71 is divided is 6, but it can be any integer of 1 or more. For example, the color gamut 71 may be divided into three colors: red, green, and blue.

[0049] <Example of coordinate positions of each point> Figure 7 shows points R, G, B, and B in Figure 6. R , point R B , point R G , point G R , point G B , and point B G This figure shows an example of the coordinate position of u'v' on the chromaticity diagram.

[0050] In the table in Figure 7, the first column lists the names of each point every two rows, and the second column lists "u'" on the upper row and "v'" on the lower row every two rows. Each column from the third onward corresponds to a color gamut Zone 0 to Zone 7, and each row in the column lists the u' coordinate position or v' coordinate position of the point corresponding to that row in the color gamut corresponding to that column.

[0051] For example, according to the table in Figure 7, the coordinate position (u', v') of point R in the reference color gamut Zone 0 is (0.499, 0.525), and the coordinate position (u', v') of point G is (0.102, 0.576). In color gamut Zone 1, the coordinate position (u', v') of point R is (0.509, 0.523), and the coordinate position (u', v') of point G is (0.092, 0.579).

[0052] <Explanation of Classification Process> Figures 8 and 9 are diagrams illustrating the classification process performed by the classification unit 53 in Figure 4.

[0053] In the example in Figure 8, the chromaticity coordinate (u) of the wide color gamut pixel is obtained from the color gamut determination unit 52. T ´,v T The chromaticity coordinate (u) is supplied to the classification unit 53. In this case, the classification unit 53 first processes the chromaticity coordinate (u) T ´,v T Based on '), its chromaticity coordinate (u T ´,v T The color gamut to which ') belongs is determined. Specifically, the classification unit 53 determines the chromaticity coordinate (u', v') as shown in Figure 8, based on the coordinate positions (u', v') of points R, G, and B in the color gamut Zone 0 to Zone 7 shown in the table in Figure 7. T ´,v T The closest color gamut Zone 3 from ( ) is its chromaticity coordinate (u T ´,v T Determine that this is the color gamut to which ') belongs.

[0054] Next, the classification unit 53 determines the chromaticity coordinate (u T ´,v T Based on '), its chromaticity coordinate (u T ´,v T The color of the color in color gamut Zone 3 to which (') belongs is determined. Specifically, the classification unit 53 determines the color of points R, G, B, B in color gamut Zone 3 as shown in the table in Figure 7. R , point R B , point R G , point G R , point G B , and point B G Based on the coordinate position (u', v'), the chromaticity coordinate (u T ´,v T The line segment BB closest to ') RIt recognizes the chromaticity coordinate (u T ´,v T The color of Zone 3, to which ') belongs, is determined to be blue.

[0055] <First example of a gain map> Figure 10 shows a first example of a gain map stored in the gain storage unit 54 of Figure 4.

[0056] As shown in Figure 10, in the gain map, the gain is registered in association with multiple color gamuts and multiple colors for which the chromaticity coordinates (u',v') of high-gamut pixels are classified during the classification process. In Figure 10, the gain is expressed as a percentage. The same applies to Figures 17 and 18, which will be described later.

[0057] As shown in Figure 10, the gain corresponding to each color gamut is set to decrease as the color gamut moves away from the reference color gamut Zone 0, that is, from color gamut Zone 1 to Zone 7. As a result, the chromaticity coordinates (u',v') of a high-gamut pixel move away from color gamut Zone 0, and the gain of that high-gamut pixel decreases.

[0058] Specifically, the gains GainR, GainG, GainB, GainC, GainM, and GainY corresponding to red, green, blue, cyan, magenta, and yellow in each color gamut can be determined, for example, by taking the HK effect into consideration, using the following equation (1).

[0059] GainR = 1 / (1 + 0.13x R / 0.01) GainG=1 / (1+0.08x G / 0.01) GainB=1 / (1+0.24x B / 0.01) GainC = 1 / (1 + 0.16x C / 0.01) GainM=1 / (1+0.19x M / 0.01) GainY=1 / (1+0.11x Y / 0.01) ... (1)

[0060] In equation (1), x R This is the point R in the color gamut corresponding to the desired gain GainR. G , point R, and point R B The broken line R connecting themG RR B and the distance between the polyline R of color gamut Zone0 G RR B is x. G x is the point G of the color gamut corresponding to the gain GainG to be obtained B , point G, and the polyline G connecting point G R GG B GG R and the distance between the polyline G of color gamut Zone0 B GG R is x. B x is the point B of the color gamut corresponding to the gain GainB to be obtained G , point B, and the polyline B connecting point B R BB G BB R and the distance between the polyline B of color gamut Zone0 G BB R is x. C x is the line segment GB of the color gamut corresponding to the gain GainC to be obtained B B G and the distance between the line segment GB of color gamut Zone0 B B G is x. M x is the line segment BR of the color gamut corresponding to the gain GainM to be obtained R R B and the distance between the line segment BR of color gamut Zone0 R R B is x. Y x is the line segment GR of the color gamut corresponding to the gain GainY to be obtained R R[[ID= sixty]] G and the distance between the line segment GR of color gamut Zone0 R B G is.

[0061] When the gain map of FIG. 10 is stored in the gain storage unit 54, the gain setting unit 55 sets the gain of the high-color gamut pixels determined to belong to the blue of color gamut Zone? to 58% (0.58) as described in FIGS? and?. T ´, v T ´) to 58% (0.58).

[0062] <Explanation of gain setting method> FIGS? and? are diagrams for explaining the gain setting method by the gain setting unit 55. [[ID= seventy-six]]

[0063] The gain setting unit 55 reads from the gain storage unit 54 the gain corresponding to the color gamut and color to which the chromaticity coordinates (u',v') of the high-gamut pixel belong, and sets it as the gain of the high-gamut pixel. Therefore, as shown in Figure 11, the gain of the high-gamut pixel is the gain GainR, GainG, GainB, GainC, GainM, or GainY calculated by the above-described equation (1).

[0064] On the other hand, the gain setting unit 55 sets the gain to 1 for low-gamut pixels. Therefore, as shown in Figure 12, the gain of a low-gamut pixel is 1, regardless of the distance of the chromaticity coordinate (u',v') of that low-gamut pixel from the reference color gamut or the corresponding color.

[0065] <Overview of the relationship between gain and u'v' chromaticity> Figures 13 and 14 illustrate the overview of the relationship between gain and u'v' chromaticity.

[0066] Specifically, Figure 13 is a diagram illustrating the relationship between the gain set by the gain setting unit 55 and the u'v' chromaticity. Figure 14 is a diagram illustrating the relationship between the gain and the u'v' chromaticity when the gain is set to 1 regardless of the chromaticity.

[0067] As shown in Figure 13, the gain of the pixel corresponding to the u'v' chromaticity coordinate within the color gamut shown in Figure 13, which is set by the gain setting unit 55, is 1 within the reference color gamut Zone 0, and outside of color gamut Zone 0, it becomes smaller as the distance from color gamut Zone 0 increases.

[0068] In contrast, as shown in Figure 14, when the gain is set to 1 regardless of chromaticity, the gain of the pixel corresponding to the u'v' chromaticity coordinate within the color gamut shown in Figure 13 is 1, regardless of the u'v' chromaticity coordinate of that pixel.

[0069] <Explanation of Display Control Process> Figure 15 is a flowchart illustrating the display control process performed by the television receiver 30 shown in Figure 3. This display control process is initiated, for example, when the RGB signals for each pixel of the television broadcast image are input from a tuner (not shown).

[0070] In step S1 of Figure 15, the video acquisition unit 31 acquires the RGB signals of each pixel of the television broadcast video input from a tuner (not shown) and supplies them to the compensation processing unit 32. In step S2, the compensation processing unit 32 performs various compensation processes on the RGB signals of each pixel acquired in step S1 and supplies them to the RGB / YCbCr conversion unit 33.

[0071] In step S3, the RGB / YCbCr conversion unit 33 converts the RGB signals of each pixel that underwent compensation processing in step S2 into YCbCr signals. The compensation processing unit 32 supplies the Cb and Cr signals of the YCbCr signal to the saturation adjustment unit 34 and the Y signal to the brightness adjustment unit 35.

[0072] In step S4, the saturation adjustment unit 34 performs a saturation adjustment process on the Cb signal and Cr signal of each pixel obtained by the processing in step S3, and supplies the resulting Cb signal and Cr signal to the gain multiplication unit 36. In step S5, the brightness adjustment unit 35 performs a brightness adjustment process on the Y signal of each pixel obtained by the processing in step S3, and supplies the resulting Y signal to the gain multiplication unit 36.

[0073] In step S6, the chromaticity conversion unit 51 of the gain multiplication unit 36 ​​converts the YCbCr signal of each pixel, which consists of the Cb signal and Cr signal that underwent saturation adjustment processing in step S4 and the Y signal that underwent luminance adjustment processing in step S5, into chromaticity coordinates (u',v'). The chromaticity conversion unit 51 supplies the chromaticity coordinates (u',v') of each pixel to the color gamut determination unit 52.

[0074] In step S7, the gain multiplication unit 36 ​​performs a gain setting process to set the gain for each pixel. Details of this gain setting process will be described later with reference to Figure 16.

[0075] In step S8, the multiplication unit 56 multiplies the Y signal of each pixel that underwent brightness adjustment processing in step S5 by the gain set for that pixel in the processing of step S7. The multiplication unit 56 then supplies the YCbCr signal for each pixel, which consists of the resulting Y signal and the Cb and Cr signals that underwent saturation adjustment processing in step S4, to the YCbCr / RGB conversion unit 37.

[0076] In step S9, the YCbCr / RGB conversion unit 37 converts the YCbCr signal of each pixel supplied from the gain multiplication unit 36 ​​into an RGB signal and supplies it to the display control unit 38. In step S10, the display control unit 38 controls the display of the display unit 39 based on the RGB signal of each pixel obtained as a result of the processing in step S9, and displays an image on the display unit 39. Then the display control process ends.

[0077] <Explanation of Gain Setting Process> Figure 16 is a flowchart illustrating the gain setting process performed by the gain multiplication unit 36 ​​in Figure 4. This gain setting process is performed for each pixel, for example, when the chromaticity coordinates (u',v') of each pixel are supplied from the chromaticity conversion unit 51 to the color gamut determination unit 52.

[0078] In step S11 of Figure 16, the color gamut determination unit 52 determines whether the chromaticity coordinates (u',v') of the pixel to be processed are outside the reference color gamut, based on the chromaticity coordinates (u',v') of the pixel to be processed supplied by the chromaticity conversion unit 51. If it is determined in step S11 that the chromaticity coordinates (u',v') are outside the reference color gamut, the color gamut determination unit 52 designates the pixel to be processed as a high-gamut pixel and supplies the chromaticity coordinates (u',v') of that high-gamut pixel to the classification unit 53. Then the process proceeds to step S12.

[0079] In step S12, the classification unit 53 performs classification processing on the wide-gamut pixels to be processed based on the chromaticity coordinates (u',v') supplied from the color gamut determination unit 52. The classification unit 53 supplies the resulting classification information to the gain setting unit 55.

[0080] In step S13, the gain setting unit 55 reads from the gain storage unit 54 the gains registered in the gain map corresponding to the color gamut and color represented by the classification information supplied from the classification unit 53. In step S14, the gain setting unit 55 sets the gains read in step S13 as the gains of the high-color-gamut pixels to be processed and supplies them to the multiplication unit 56. The gain setting process then ends.

[0081] On the other hand, if it is determined in step S11 that the chromaticity coordinates (u',v') do not exist outside the reference color gamut, the color gamut determination unit 52 treats the pixel to be processed as a low-color-gamut pixel and supplies the determination result for that low-color-gamut pixel to the gain setting unit 55. Then the process proceeds to step S15.

[0082] In step S15, the gain setting unit 55 sets the gain of the low-gamut pixels to be processed to 1 based on the determination result supplied from the color gamut determination unit 52, and supplies it to the multiplication unit 56. The gain setting process then ends.

[0083] <Examples of gain ranges registered in the gain map> Figures 17 and 18 show the first and second examples of gain ranges registered in the gain map, respectively.

[0084] The tables in Figures 17 and 18 show gain maps, and the minimum (Min) and maximum (Max) values ​​of the numerical values ​​set as the gain are listed in the gain column of the gain map. For example, in the gain map of Figure 17, any value in the range of 84% to 94% is registered as the gain corresponding to red in color gamut Zone 1. In the examples of Figures 17 and 18, as in the example of Figure 10, the gain corresponding to each color gamut is set to decrease as the color gamut moves away from the reference color gamut Zone 0, that is, from color gamut Zone 1 to Zone 7. As a result, the chromaticity coordinates (u',v') of a high-gamut pixel move away from color gamut Zone 0, the smaller the gain of that high-gamut pixel becomes.

[0085] For example, the gain map in the example of Figure 10 is the most desirable, followed by the gain map with registered gains within the range of the example of Figure 17, and then the gain map with registered gains within the range of the example of Figure 18.

[0086] In this embodiment, an RGB signal is input to the television receiver 30, but an RGBW signal, which is an RGB signal with a W signal (white signal) representing white added to it, may also be input. In this case, the RGB / YCbCr conversion unit 33 supplies the W signal to the YCbCr / RGB conversion unit 37, and the YCbCr / RGB conversion unit 37 adds the W signal to the converted RGB signal and supplies the RGBW signal to the display control unit 38. The display control unit 38 controls the display of the display unit 39 based on this RGBW signal.

[0087] In the classification process, it is also possible to perform only one of the following: determining which of the multiple color gamuts the chromaticity coordinate (u',v') belongs to, or determining which of the multiple colors it belongs to. In this case, the gain is set for each of the multiple color gamuts into which the chromaticity coordinate (u',v') is classified, or for each of the multiple colors.

[0088] As described above, in the television receiver 30, the color gamut determination unit 52 determines whether the chromaticity of a pixel exceeds the reference color gamut based on the pixel's chromaticity coordinates (u',v'). If the color gamut determination unit 52 determines that the chromaticity of a pixel exceeds the reference color gamut, the multiplier unit 56 multiplies the Y signal of that pixel by a gain less than 1. The display control unit 38 controls the display of a pixel based on the Y signal of the pixel obtained as a result of the multiplication by the multiplier unit 56, and the Cb and Cr signals of that pixel. Therefore, the television receiver 30 can reduce the Y signal of high-gamut pixels. As a result, power consumption can be suppressed while maintaining the display of a natural image due to the HK effect. In addition, if the display unit 39 is an OLED display, the burn-in life of the display unit 39 can be extended.

[0089] This technology can also be applied to display devices that show images, other than television receivers.

[0090] <3. Computers> The series of processes described above can be executed by hardware or by software. When the series of processes are executed by software, the programs that make up the software are installed on a computer. Here, a computer includes computers built into dedicated hardware, as well as general-purpose personal computers that can perform various functions by installing various programs.

[0091] Figure 19 is a block diagram showing an example of the hardware configuration of a computer that executes the series of processes described above using a program.

[0092] In a computer, the CPU (Central Processing Unit) 901, ROM (Read Only Memory) 902, and RAM (Random Access Memory) 903 are interconnected by a bus 904.

[0093] An input / output interface 905 is further connected to the bus 904. An input unit 906, an output unit 907, a storage unit 908, a communication unit 909, and a drive 910 are connected to the input / output interface 905.

[0094] The input unit 906 consists of a keyboard, mouse, microphone, etc. The output unit 907 corresponds to the display unit 39 and consists of a display, speaker, etc. The storage unit 908 consists of a hard disk, non-volatile memory, etc. The communication unit 909 consists of a network interface, etc. The drive 910 drives removable media 911 such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory.

[0095] In a computer configured as described above, the CPU 901 loads a program stored in the memory unit 908 into the RAM 903 via the input / output interface 905 and the bus 904, and executes it, thereby performing the series of processes described above. Specifically, the CPU 901 functions as, for example, an image acquisition unit 31, a compensation processing unit 32, an RGB / YCbCr conversion unit 33, a saturation adjustment unit 34, a brightness adjustment unit 35, a gain multiplication unit 36, a YCbCr / RGB conversion unit 37, and a display control unit 38.

[0096] The program executed by the computer (CPU 901) can be provided by recording it on a removable medium 911, such as a package medium. The program can also be provided via wired or wireless transmission media, such as a local area network, the internet, or digital satellite broadcasting.

[0097] In a computer, a program can be installed in the storage unit 908 via the input / output interface 905 by inserting a removable media 911 into the drive 910. Alternatively, a program can be received by the communication unit 909 via a wired or wireless transmission medium and installed in the storage unit 908. Furthermore, programs can be pre-installed in the ROM 902 or the storage unit 908.

[0098] The programs executed by the computer may be programs that are processed chronologically in the order described herein, or they may be programs that are processed in parallel or at necessary times, such as when a call is made.

[0099] The embodiments of this technology are not limited to those described above, and various modifications are possible without departing from the spirit of this technology.

[0100] For example, this technology can be configured as cloud computing, where a single function is shared and processed collaboratively by multiple devices via a network.

[0101] Furthermore, each step described in the flowchart above can be performed by a single device, or it can be divided and performed by multiple devices.

[0102] Furthermore, if a single step includes multiple processes, those processes can be executed by a single device or shared among multiple devices.

[0103] The effects described herein are merely illustrative and not limited to those described herein; other effects may also occur.

[0104] The technology can take the following configurations: (1) A display device comprising: a color gamut determination unit that determines whether the chromaticity of a pixel exceeds a reference color gamut, which is a reference color gamut, based on the chromaticity of the pixel; a multiplication unit that multiplies the luminance signal of the pixel by a gain less than 1 when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut; and a display control unit that controls the display of the pixel based on the luminance signal and the color difference signal of the pixel obtained as a result of multiplication by the multiplication unit. (2) The display device according to (1), wherein the gain is configured to decrease as the chromaticity moves away from the reference color gamut. (3) The display device according to (1) or (2), wherein the color gamut determination unit determines that the chromaticity exceeds the reference color gamut, and further comprises a classification unit that determines which of a plurality of color gamuts the chromaticity belongs to, wherein the gain is set for each of the plurality of color gamuts, and the multiplication unit is configured to multiply the luminance signal by the gain corresponding to the color gamut to which the classification unit determines the chromaticity belongs when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut. (4) The display device according to (1) or (2), wherein the color gamut determination unit determines that the chromaticity exceeds the reference color gamut, and further comprises a classification unit that determines which of a plurality of colors the chromaticity belongs to, wherein the gain is set for each of the plurality of colors, and the multiplication unit is configured to multiply the luminance signal by the gain corresponding to the color to which the classification unit determines the chromaticity belongs when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut. (5) The display device according to (4), wherein the plurality of colors are red, green, and blue. (6) The display device according to (4), wherein the plurality of colors are red, green, blue, cyan, magenta, and yellow.(7) The display device according to (1) or (2), wherein, if the color gamut determination unit determines that the chromaticity exceeds the reference color gamut, the display device further comprises a classification unit that determines which of the plurality of color gamuts the chromaticity belongs to and which of the plurality of colors in the color gamut to which it belongs, the gain is set for each of the plurality of colors in each of the plurality of color gamuts, and the multiplication unit is configured to multiply the luminance signal by the gain corresponding to the color gamut and the color to which the classification unit determines that the chromaticity belongs when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut. (8) The display device according to (7), wherein the plurality of colors are configured to be red, green, and blue. (9) The display device according to (7), wherein the plurality of colors are configured to be red, green, blue, cyan, magenta, and yellow. (10) The display device according to any one of (1) to (9), wherein the display control unit is also configured to control the display of the pixel based on a white signal representing the white of the pixel. (11) A display device according to any one of (1) to (10) above, wherein the reference color gamut is configured to be 75% of the BT.2020 color gamut. (12) A display device according to (11) above, further comprising a display unit that displays the pixels under the control of the display control unit, wherein the color gamut of the display unit is configured to be wider than the BT.2020 color gamut. (13) A display control method for a display device, comprising: determining whether the chromaticity of a pixel exceeds a reference color gamut, which is a reference color gamut, based on the chromaticity of the pixel; multiplying the luminance signal of the pixel by a gain less than 1 if it is determined that the chromaticity exceeds the reference color gamut; and controlling the display of the pixel based on the luminance signal and the color difference signal of the pixel obtained as a result of the multiplication.(14) A program for causing a computer to function as a display control unit that controls the display of a pixel based on the chromaticity of the pixel, a color gamut determination unit that determines whether the chromaticity of the pixel exceeds a reference color gamut, a reference color gamut; a multiplication unit that multiplies the luminance signal of the pixel by a gain less than 1 when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut; and the luminance signal obtained as a result of multiplication by the multiplication unit and the color difference signal of the pixel.

[0105] 30 Television receiver, 38 Display control unit, 39 Display unit, 52 Color gamut determination unit, 53 Classification unit, 56 Multiplication unit

Claims

1. A display device comprising: a color gamut determination unit that determines whether the chromaticity of a pixel exceeds a reference color gamut, which is a reference color gamut, based on the chromaticity of the pixel; a multiplication unit that multiplies the luminance signal of the pixel by a gain less than 1 if the color gamut determination unit determines that the chromaticity exceeds the reference color gamut; and a display control unit that controls the display of the pixel based on the luminance signal obtained as a result of multiplication by the multiplication unit and the color difference signal of the pixel.

2. The display device according to claim 1, wherein the gain is configured to decrease as the chromaticity moves away from the reference color gamut.

3. The display device according to claim 1, further comprising a classification unit that determines which of a plurality of color gamuts the chromaticity belongs to when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut, wherein the gain is set for each of the plurality of color gamuts, and the multiplication unit is configured to multiply the luminance signal by the gain corresponding to the color gamut to which the classification unit determines to belong when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut.

4. The display device according to claim 1, further comprising a classification unit that determines which of a plurality of colors the chromaticity belongs to when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut, wherein the gain is set for each of the plurality of colors, and the multiplication unit is configured to multiply the luminance signal by the gain corresponding to the color to which the classification unit determines the chromaticity belongs when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut.

5. The display device according to claim 4, wherein the plurality of colors are configured to be red, green, and blue.

6. The display device according to claim 4, wherein the plurality of colors are configured to be red, green, blue, cyan, magenta, and yellow.

7. The display device according to claim 1, wherein, if the color gamut determination unit determines that the chromaticity exceeds the reference color gamut, the display device further comprises a classification unit that determines which of the plurality of color gamuts the chromaticity belongs to and which of the plurality of colors in the color gamut to which it belongs, the gain is set for each of the plurality of colors in each of the plurality of color gamuts, and the multiplication unit is configured to multiply the luminance signal by the gain corresponding to the color gamut and the color to which the classification unit determines that the chromaticity belongs when the color gamut determination unit determines that the chromaticity exceeds the reference color gamut.

8. The display device according to claim 7, wherein the plurality of colors are configured to be red, green, and blue.

9. The display device according to claim 7, wherein the plurality of colors are configured to be red, green, blue, cyan, magenta, and yellow.

10. The display device according to claim 1, wherein the display control unit is also configured to control the display of the pixels based on a white signal representing the white color of the pixels.

11. The display device according to claim 1, wherein the reference color gamut is configured to be 75% of the BT.2020 color gamut.

12. The display device according to claim 11, further comprising a display unit that displays the pixels under the control of the display control unit, wherein the color gamut of the display unit is configured to be wider than BT.2020.

13. A display control method comprising: determining whether the chromaticity of a pixel exceeds a reference color gamut, which is a reference color gamut, based on the chromaticity of the pixel; multiplying the luminance signal of the pixel by a gain less than 1 if it is determined that the chromaticity exceeds the reference color gamut; and controlling the display of the pixel based on the luminance signal and the color difference signal of the pixel obtained as a result of the multiplication.

14. A program for causing a computer to function as a display control unit that controls the display of a pixel based on the chromaticity of the pixel, the chromaticity of the pixel exceeds a reference color gamut, which is a reference color gamut, the chromaticity of the pixel is determined to exceed the reference color gamut by the color gamut determination unit, and the luminance signal of the pixel is multiplied by a gain of less than 1, and the luminance signal and the color difference signal of the pixel obtained as a result of multiplication by the multiplier unit.

Images