JP2015197461A - Multi-primary color display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a multi-primary color display device that can be improved in resolution through display using virtual pixels from having a reverse phenomenon of luminance between an input side and an output side.SOLUTION: A multi-primary color display device includes a multi-primary color display panel and a signal conversion circuit 20 which converts an input image signal into a multi-primary color image signal, and can make a display of two adjacent pixels of an input image with two virtual pixels by portioning out a red sub-pixels R, a green sub-pixel G, a blue sub-pixel B, and a yellow sub-pixel Ye constituting a pixel P to the two virtual pixels. The signal conversion circuit has a low-frequency multi-primary color signal generation part 21. The low-frequency multi-primary color signal generation part can perform multi-primary color conversion processing on a low-frequency component so that when one of the two adjacent pixels of the input image represents a specific color, the ratio of the absolute luminance of the yellow sub-pixel to the sum of the absolute luminance of the red sub-pixel and the absolute luminance of the green sub-pixel is 0.5-2.0.

Description

  The present invention relates to a multi-primary color display device.

  In a general display device, one pixel is composed of three sub-pixels that display the three primary colors of light, red, green, and blue, thereby enabling color display.

  However, the conventional display device has a problem that a displayable color range (referred to as a “color reproduction range”) is narrow. When the color reproduction range is narrow, it is impossible to display a part of the object color (the colors of various objects existing in nature; see Non-Patent Document 1). Therefore, in order to widen the color reproduction range of the display device, a method of increasing the number of primary colors used for display has been proposed.

  For example, Patent Document 1 discloses a display device that performs display using six primary colors. Patent Document 1 also discloses a display device that performs display using four primary colors and a display device that performs display using five primary colors. An example of a display device that performs display using the six primary colors is shown in FIG. In the display device 800 shown in FIG. 16, one pixel P is constituted by the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, the cyan sub-pixel C, the magenta sub-pixel M, and the yellow sub-pixel Ye. In the display device 800, color display is performed by mixing the six primary colors red, green, blue, cyan, magenta, and yellow displayed by the six sub-pixels.

  By increasing the number of primary colors used for display, that is, by performing display using four or more primary colors, the color reproduction range can be made wider than that of a conventional display device that performs display using three primary colors. In the present specification, a display device that performs display using four or more primary colors is referred to as a “multi-primary color display device”, and a display device that performs display using three primary colors (that is, a conventional general) is referred to as “three primary colors”. It is referred to as a “display device”.

  However, in order to display an image having the same resolution as that of the three primary color display device in the multi-primary color display device, if the screen size is the same, the device structure needs to be made finer, and the production cost increases. This is because, in a multi-primary color display device, the number of sub-pixels per pixel increases from 3 to 4 or more. Therefore, in order to realize the same number of pixels with the same screen size, the size of the sub-pixels compared to the three primary color display device. This is because it must be made smaller. Specifically, if the number of primary colors used for display is m (m ≧ 4), the size of the sub-pixel must be 3 / m. For example, in a multi-primary color display device that performs display using six primary colors, the size of the sub-pixel needs to be ½ (= 3/6).

  Therefore, Patent Document 2 proposes a technique for displaying an image with the same or higher resolution in a multi-primary color display device without reducing the subpixel size as compared with the three primary color display device. As shown in FIG. 17, in the multi-primary color display device 900 of Patent Document 2, a plurality of sub-pixels SP1 to SP6 that constitute one pixel P are a plurality of virtual pixels (hereinafter referred to as “virtual pixels”). It is possible to distribute the display to VP1 and VP2 and display each virtual pixel as a display unit.

  FIG. 18 shows a signal conversion circuit 920 included in the multi-primary color display device 900 of Patent Document 2. As illustrated in FIG. 18, the signal conversion circuit 920 includes a low-frequency multi-primary color signal generation unit 921, a high-frequency luminance signal generation unit 922, and a rendering processing unit 923. The signal conversion circuit 920 further includes a γ correction unit 924 and an inverse γ correction unit 925.

  The input image signal to the signal conversion circuit 920 is first subjected to γ correction processing by the γ correction unit 924. Next, the image signal subjected to the γ correction processing is input to the low-frequency multi-primary color signal generation unit 921 and the high-frequency luminance signal generation unit 922, respectively.

  The low-frequency multi-primary color signal generation unit 921 generates a low-frequency multi-primary color signal based on the input image signal. The low-frequency multi-primary color signal is a signal in which low-frequency components (components having a relatively low spatial frequency) of the input image signal are converted into multi-primary colors (that is, converted so as to correspond to four or more primary colors). .

  The low-frequency multi-primary color signal generation unit 921 includes a low-frequency component extraction unit (low-pass filter: LPF) 926 and a multi-primary color conversion unit 927. The low pass filter 926 extracts a low frequency component from the input image signal. The low-frequency component of the input image signal extracted by the low-pass filter 926 is converted into multi-primary colors by the multi-primary color conversion unit 927. The multi-primary low-frequency component is output as a low-frequency multi-primary color signal.

  The high frequency luminance signal generation unit 922 generates a high frequency luminance signal based on the input image signal. The high frequency luminance signal is a signal obtained by luminance conversion of a high frequency component (component having a relatively high spatial frequency) of the input image signal.

  The high frequency luminance signal generation unit 922 includes a luminance conversion unit 928 and a high frequency component extraction unit (high bus filter: HPF) 929. The luminance conversion unit 928 performs luminance conversion on the input image signal to generate a luminance signal. The high pass filter 929 extracts the high frequency component of the luminance signal generated by the luminance conversion unit 928 as a high frequency luminance signal.

  The rendering processing unit 923 converts the low-frequency multi-primary color signal generated by the low-frequency multi-primary color signal generation unit 921 and the high-frequency luminance signal generated by the high-frequency luminance signal generation unit 922 to a plurality of virtual pixels. Perform the rendering process. The rendering processing unit 923 includes a storage unit 923a that stores a weighting factor that defines a distribution pattern of a plurality of subpixels to a plurality of virtual pixels, and selects a preferable weighting factor according to the resolution of the input image and the like. The rendering process is performed in accordance with the distribution pattern defined by the selected weight coefficient. The image signal generated by the rendering process is subjected to inverse γ correction by the inverse γ correction unit 925 and output as a multi-primary color image signal.

  Thus, the signal conversion circuit 920 performs multi-primary color processing on the low frequency components of the input image signal and performs luminance conversion processing on the high frequency components. An image signal (multi-primary color image signal) corresponding to the four primary colors can be output by combining the low-frequency multi-primary color signal and the high-frequency luminance signal obtained by these processes and rendering to a virtual pixel.

International Publication No. 2006/018926 International Publication No. 2012/067038

M. R. Pointer, "The gamut of real surface colors", Color Research and Application, Vol.5, No.3, pp.145-155 (1980)

  However, according to the study of the present inventor, it has been found that if the technique disclosed in Patent Document 2 is simply used, a problem occurs when a specific input image is displayed.

  Specifically, when focusing on two pixels adjacent to each other in the input image, it has been found that the magnitude relationship between the luminances of the two pixels may be reversed between the input side and the output side. For example, in the input image, the luminance of the virtual pixels for performing display corresponding to the pixels in the odd-numbered columns even though the pixels in the odd-numbered columns indicate black and the pixels in the even-numbered columns indicate halftone chromatic colors. However, the luminance of the virtual pixel for performing display corresponding to the pixels in the even-numbered columns may be higher. Hereinafter, this phenomenon may be referred to as “luminance reversal phenomenon”.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a multi-primary color display device capable of improving the resolution by display using virtual pixels, on the input side and the output side as described above. This is to prevent the occurrence of the luminance reversal phenomenon.

  A multi-primary color display device according to an embodiment of the present invention has a pixel composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a yellow sub-pixel, and uses four primary colors of red, green, blue, and yellow. A multi-primary color display device performing color display, wherein each pixel has the red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel, and an input image signal corresponding to three primary colors A signal conversion circuit that converts the image signal into a multi-primary color image signal corresponding to the four primary colors, and the red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel constituting the pixel are The two virtual pixels can be displayed by allocating to the virtual pixels and adjacent two pixels in the input image can be displayed, and the signal conversion circuit can generate a low frequency component of the input image signal based on the input image signal. A low-frequency multi-primary color signal generation unit that generates a low-frequency multi-primary color signal that is a multi-primary signal, and a signal obtained by luminance-converting a high-frequency component of the input image signal based on the input image signal A high-frequency luminance signal generating unit that generates a high-frequency luminance signal, and a rendering processing unit that performs rendering processing on the two virtual pixels based on the low-frequency multi-primary color signal and the high-frequency luminance signal. The low-frequency multi-primary color signal generator generates absolute luminance of the red sub-pixel and absolute luminance of the green sub-pixel when one of the two adjacent pixels in the input image indicates a specific color. The low-frequency component can be multi-primary so that the ratio of the absolute luminance of the yellow sub-pixel to the sum is 0.5 or more and 2.0 or less.

  In one embodiment, the specific color is a chromatic color, and the standardized luminance of blue is a color larger than 1/3 of the larger of the normalized luminance of red and the normalized luminance of green. is there.

  In one embodiment, the low-frequency multi-primary color signal generator generates a sum of absolute luminance of the red sub-pixel and absolute luminance of the green sub-pixel when the one pixel in the input image indicates the specific color. Multiple primary colors can be formed so that the absolute luminance ratio of the yellow sub-pixel is substantially 1.

In one embodiment, when the one pixel in the input image indicates the specific color, the low-frequency multi-primary color signal generation unit is configured to view a color represented by the low-frequency multi-primary color signal from the front direction. Color difference Δu′v ′ defined by chromaticity coordinates (u ′, v ′) indicating chromaticity and chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) indicating chromaticity when viewed from an oblique direction of 60 ° = ((U′−u ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) Multiple primary colors can be made so that ^1/2 is 0.03 or less.

In one embodiment, the specific color is a dark skin, and the low-frequency multi-primary color signal generator generates a color represented by the low-frequency multi-primary color signal when the one pixel in the input image indicates a dark skin. the chromaticity coordinates indicating the chromaticity when viewed from the front direction (u ', v') and the chromaticity coordinates showing the chromaticity when viewed from a 60 ° oblique direction _{(u 60 ', v 60'} ) and by The specified primary color difference Δu′v ′ = ((u′−u ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) can be converted to multiple primary colors so that ^1/2 is 0.03 or less.

In one embodiment, the specific color is a light skin, and the low-frequency multi-primary color signal generator generates a color represented by the low-frequency multi-primary color signal when the one pixel in the input image indicates a light skin. the chromaticity coordinates indicating the chromaticity when viewed from the front direction (u ', v') and the chromaticity coordinates showing the chromaticity when viewed from a 60 ° oblique direction _{(u 60 ', v 60'} ) and by Specified color difference Δu′v ′ = ((u′−u ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) Multiple primary colors can be formed so that ^1/2 is 0.01 or less.

  In one embodiment, when the one of the two adjacent pixels in the input image indicates a specific color, the other pixel indicates black.

  In one embodiment, each of the two virtual pixels is composed of two or more subpixels of the red subpixel, the green subpixel, the blue subpixel, and the yellow subpixel.

  In one embodiment, a plurality of the pixels are arranged in a matrix including a plurality of rows and a plurality of columns, and the red sub-pixel, the green sub-pixel, and the blue sub-pixel are respectively included in the plurality of pixels. The yellow sub-pixels are arranged in one row and four columns.

  In one embodiment, the multi-primary color display device according to the present invention is a liquid crystal display device.

  Alternatively, the multi-primary color display device according to the embodiment of the present invention includes a pixel composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a yellow sub-pixel, and has four primary colors of red, green, blue, and yellow. A multi-primary color display device that performs color display using a multi-primary color display panel having the red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel in each pixel, and an input corresponding to three primary colors A signal conversion circuit that converts an image signal into a multi-primary color image signal corresponding to the four primary colors, and the red subpixel, the green subpixel, the blue subpixel, and the yellow subpixel that constitute the pixel The two virtual pixels can be distributed and displayed for two adjacent pixels in the input image by the two virtual pixels, and the signal conversion circuit can generate the input image signal based on the input image signal. A low-frequency multi-primary color signal generation unit that generates a low-frequency multi-primary color signal, which is a signal in which low-frequency components are converted into multi-primary colors, and luminance conversion of the high-frequency component of the input image signal based on the input image signal A high-frequency luminance signal generating unit that generates a high-frequency luminance signal that is a signal, a rendering processing unit that performs rendering processing on the two virtual pixels based on the low-frequency multi-primary color signal and the high-frequency luminance signal, The low-frequency multi-primary color signal generation unit includes a magnitude relationship between luminances of one of the adjacent two pixels and the other pixel in the input image, a virtual pixel corresponding to the one pixel, and The low-frequency component can be converted into multiple primary colors so that the magnitude relationship of the luminance of the virtual pixel corresponding to the other pixel is not reversed.

  According to an embodiment of the present invention, in a multi-primary color display device that can improve resolution by display using virtual pixels, it is to prevent the occurrence of a luminance reversal phenomenon between the input side and the output side.

1 is a block diagram schematically showing a liquid crystal display device (multi-primary color display device) 100 according to an embodiment of the present invention. 3 is a diagram illustrating an example of sub-pixel arrangement of a multi-primary color display panel 10 included in the liquid crystal display device 100. FIG. 3 is a diagram illustrating an example of sub-pixel arrangement of a multi-primary color display panel 10 included in the liquid crystal display device 100. FIG. It is a figure which shows the example of the distribution pattern of the sub pixel to two virtual pixels. It is a figure which shows the example of the distribution pattern of the sub pixel to two virtual pixels. 3 is a block diagram schematically showing a signal conversion circuit 20 provided in the liquid crystal display device 100. FIG. (A)-(l) is a figure which shows the example of multi-primary color conversion in case the pixel of an odd-numbered row | line | column shows black and the pixel of an even-numbered row | line | column shows gray (halftone achromatic color) in an input image. . (A) to (l) are multi-primary color conversions in the case where both odd-numbered pixels and even-numbered pixels in the input image indicate dark skin (that is, when the input image is a solid image of dark skin). It is a figure which shows an example. (A)-(l) is a figure which shows the example of multi-primary color conversion in case the pixel of an odd number column shows black and the pixel of an even number column has shown the dark skin in the input image. The color reproduction range of the multi-primary color display panel 10 and the BT. 7 is a chromaticity diagram illustrating a color gamut of 709; FIG. (A)-(l) is a figure which shows the example of multi-primary color conversion when the pixel of an odd-numbered row | line | column shows black and the pixel of an even-numbered row | line | column shows the dark skin in an input image, The case where the combination of the sub-pixel brightness of the first embodiment is selected is shown. (A)-(l) is a figure which shows the example of multi-primary color conversion when the pixel of an odd-numbered row | line | column shows black and the pixel of an even-numbered row | line | column shows the dark skin in an input image, The case where the combination of the sub-pixel luminance of Example 2 is selected is shown. (A)-(l) is a figure which shows the example of multi-primary color conversion in case the pixel of an odd-numbered row | line | column shows a dark skin, and the pixel of an even-numbered row | line | column has shown black in the input image. The case where the combination of the sub-pixel luminance of Example 3 is selected is shown. (A)-(l) is a figure which shows the example of multi-primary color conversion when the pixel of an odd-numbered row | line | column shows black and the pixel of an even-numbered row | line | column shows the dark skin in an input image, FIG. 9 shows a case where a combination of sub-pixel luminances in the comparative example is selected. (A)-(l) is a figure which shows the example of multi-primary color conversion in case the pixel of an odd number column shows black and the pixel of an even number column has shown the dark skin in the input image. It is a figure which shows typically the conventional display apparatus 800 which displays using six primary colors. It is a figure which shows typically the multi-primary-color display apparatus 900 currently disclosed by patent document 2. FIG. 10 is a block diagram schematically showing a signal conversion circuit 920 included in the multi-primary color display device 900 of Patent Document 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, although a liquid crystal display device is illustrated below, this invention is not limited to a liquid crystal display device.

  FIG. 1 shows a liquid crystal display device 100 according to this embodiment. As shown in FIG. 1, the liquid crystal display device 100 includes a multi-primary color display panel 10 and a signal conversion circuit 20, and performs display using four primary colors of red, green, blue, and yellow ( 4 primary color display device).

  Although not shown in FIG. 1, the multi-primary color display panel 10 has pixels composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a yellow sub-pixel. A plurality of pixels are arranged in a matrix including a plurality of rows and a plurality of columns. FIG. 2 shows an example of a specific pixel structure (sub-pixel arrangement) of the multi-primary color display panel 10.

  As shown in FIG. 2, each pixel P of the multi-primary color display panel 10 is composed of four sub-pixels. More specifically, a red sub-pixel R that displays red and a green sub-pixel that displays green G, a blue sub-pixel B that displays blue, and a yellow sub-pixel Ye that displays yellow. Within each pixel P, the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye are arranged in one row and four columns.

  In the example shown in FIG. 2, in each pixel P, the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye are arranged in this order from the left side to the right side. The sub-pixel arrangement is not limited to this. For example, as shown in FIG. 3, in each pixel P, the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye may be arranged in this order from the right side to the left side. Good.

  As shown in FIG. 1, the signal conversion circuit 20 converts an input image signal (three primary color image signals) corresponding to three primary colors (RGB) into an image signal corresponding to four primary colors (referred to as “multi-primary color image signal”). Convert to The multi-primary color image signal output from the signal conversion circuit 20 is input to the multi-primary color display panel 10, and color display using the four primary colors is performed. A specific configuration of the signal conversion circuit 20 will be described in detail later.

  In the liquid crystal display device 100 according to the present embodiment, the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye constituting each pixel P are divided into two virtual pixels (“first virtual pixel” and “first virtual pixel”). 2 virtual pixels ”) and display of two adjacent pixels in the input image can be performed by these two virtual pixels. Each of the two virtual pixels includes two or more sub-pixels among the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye. FIG. 4 shows an example of a distribution pattern of sub-pixels to two virtual pixels.

  As shown in FIG. 4, the red subpixel R, the green subpixel G, the blue subpixel B, and the yellow subpixel Ye are distributed to two virtual pixels (first virtual pixel and second virtual pixel) VP1 and VP2. The first virtual pixel VP1 includes a red subpixel R, a green subpixel G, and a blue subpixel B. The second virtual pixel VP2 includes a blue subpixel B and a yellow subpixel Ye. In the example illustrated in FIG. 4, the first virtual pixel VP1 and the second virtual pixel VP2 include a blue subpixel B as a common subpixel, and share the blue subpixel B.

  Note that the number and combination of sub-pixels constituting each of the first virtual pixel VP1 and the second virtual pixel VP2 are not limited to the example shown in FIG. Further, in the distribution pattern illustrated in FIG. 4, each of the first virtual pixel VP1 and the second virtual pixel VP2 is configured by two or more subpixels continuous in one pixel P. It is not limited to this.

  FIG. 5 shows another example of the distribution pattern. The first virtual pixel VP1 shown in FIG. 5 includes a red subpixel R, a green subpixel G, and a blue subpixel B of the left pixel P. The second virtual pixel VP2 includes a blue subpixel B and a yellow subpixel Ye of the left pixel P, and a red subpixel R of the right pixel P.

  In the example illustrated in FIG. 5, the second virtual pixel VP <b> 2 is configured by a plurality of (here, three) sub-pixels extending across the two pixels P. Thus, the virtual pixel may straddle the two pixels P.

  As described above, the liquid crystal display device 100 includes a plurality of sub-pixels (the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye) that constitute each pixel P as two virtual pixels (first sub-pixels). 1 virtual pixel VP1 and second virtual pixel VP2), and information can be displayed independently by each virtual pixel. Therefore, the display for two adjacent pixels in the input image can be performed by these two virtual pixels.

  Next, a specific configuration of the signal conversion circuit 20 will be described. FIG. 6 shows an example of a specific configuration of the signal conversion circuit 20.

  As illustrated in FIG. 6, the signal conversion circuit 20 includes a low-frequency multi-primary color signal generation unit 21, a high-frequency luminance signal generation unit 22, and a rendering processing unit 23. The signal conversion circuit 20 further includes a γ correction unit 24 and an inverse γ correction unit 25.

  The input image signal to the signal conversion circuit 20 is first subjected to γ correction processing by the γ correction unit 24. Next, the image signal that has been subjected to the γ correction processing is input to the low-frequency multi-primary color signal generation unit 21 and the high-frequency luminance signal generation unit 22, respectively.

  The low-frequency multi-primary color signal generation unit 21 generates a low-frequency multi-primary color signal based on the input image signal. The low-frequency multi-primary color signal is a signal obtained by converting low-frequency components (components having a relatively low spatial frequency) of the input image signal into multi-primary colors (that is, converted so as to correspond to the four primary colors).

  Specifically, the low-frequency multi-primary color signal generation unit 21 includes a low-frequency component extraction unit (here, a low-pass filter: LPF) 26 and a multi-primary color conversion unit 27. The low pass filter 26 extracts a low frequency component from the input image signal. The low-frequency component of the input image signal extracted by the low-pass filter 26 is converted into multi-primary colors by the multi-primary color conversion unit 27. The multi-primary low-frequency component is output as a low-frequency multi-primary color signal.

  The high frequency luminance signal generation unit 22 generates a high frequency luminance signal based on the input image signal. The high frequency luminance signal is a signal obtained by luminance conversion of a high frequency component (component having a relatively high spatial frequency) of the input image signal.

  Specifically, the high frequency luminance signal generation unit 22 includes a luminance conversion unit 28 and a high frequency component extraction unit (here, a high-pass filter: HPF) 29. The luminance conversion unit 28 performs luminance conversion on the input image signal to generate a luminance signal. The high pass filter 29 extracts the high frequency component of the luminance signal generated by the luminance conversion unit 28 as a high frequency luminance signal.

  The rendering processing unit 23 outputs two virtual pixels based on the low-frequency multi-primary color signal generated by the low-frequency multi-primary color signal generation unit 21 and the high-frequency luminance signal generated by the high-frequency luminance signal generation unit 22. Perform the rendering process. The image signal generated by the rendering process is subjected to inverse γ correction by the inverse γ correction unit 25 and is output as a multi-primary color image signal.

  In this way, the signal conversion circuit 20 considers human visual characteristics that the sensitivity to the luminance signal is superior to the color signal (that is, the visibility of the color difference is lower than the luminance visibility), Multi-primary color processing is performed on the low-frequency component of the input image signal, and luminance conversion processing is performed on the high-frequency component. An image signal (multi-primary color image signal) corresponding to the four primary colors can be output by combining the low-frequency multi-primary color signal and the high-frequency luminance signal obtained by these processes and rendering to a virtual pixel.

  In the liquid crystal display device 100 of the present embodiment, the low-frequency multi-primary color signal generation unit 21 satisfies the predetermined relationship between the luminance values of the red sub-pixel R, the green sub-pixel G, and the yellow sub-pixel Ye for a specific input image signal. As described above, it is possible to perform multi-primary color formation of low-frequency components. Specifically, the low frequency multi-primary color signal generation unit 21 determines the absolute luminance of the red sub-pixel R and the absolute luminance of the green sub-pixel G when one of the two adjacent pixels in the input image indicates a specific color. Multi-primary colors of low-frequency components can be obtained so that the ratio of the absolute luminance of the yellow sub-pixel to the luminance sum is 0.5 or more and 2.0 or less.

  Here, what kind of input image signal the luminance reversal phenomenon will occur will be described.

  FIG. 7 is a diagram illustrating an example of multi-primary color conversion in a case where odd-numbered columns of pixels indicate black and even-numbered columns of pixels indicate gray (halftone achromatic color) in the input image.

  In this case, in the input image signal, as shown in FIG. 7A, the red, green, and blue luminances (standardized luminance) are zero for the odd-numbered pixels, and the red for the even-numbered pixels. , Green and blue luminances (standardized luminance) are the same value greater than zero.

  First, an input image signal is passed through an LPF (low-pass filter), and as shown in FIG. 7B, a red, green, and blue luminance is averaged by two pixels. When this signal is simply converted into multi-primary colors (4-color conversion), as shown in FIG. 7C, the luminances of red, green, blue, and yellow are the same (but not zero). Multi-primary color signal) is obtained.

  On the other hand, as shown in FIG. 7D, a white component (corresponding to a luminance signal) corresponding to the minimum values of red, green, and blue luminance is extracted from the input image signal. Next, the extracted white component is passed through an HPF (high-pass filter) and corresponds to an odd number column as shown in FIG. 7 (e) and an even number column as shown in FIG. 7 (f). Separate into minutes. Subsequently, as shown in FIGS. 7G and 7H, each of the separated white components is converted into the luminance of the color of the sub-pixel constituting the corresponding virtual pixel. That is, the white component corresponding to the odd number column is converted into the luminance of the color (red, green, blue) of the sub-pixel constituting the virtual pixel corresponding to the odd number column, and the white component corresponding to the even number example is converted to the even number column. The luminance is converted to the luminance of the color (blue, yellow, red) of the sub-pixel constituting the corresponding virtual pixel. Since the white component corresponding to the odd-numbered columns is zero, as shown in FIG. 7G, the luminance of each color after conversion is also zero. On the other hand, since the white component corresponding to the even-numbered columns is not zero, the luminance of each color after conversion is not zero as shown in FIG. Thereafter, as shown in FIG.

  The luminance after the addition is further added to the low-frequency multi-primary color signal. However, in this summation, the white component extracted from the input image signal is passed through the LPF (see FIG. 7 (j)) is subtracted from the low-frequency multi-primary color signal (see FIG. 7 (k)). The later luminance (here, zero for all colors) is added to the luminance shown in FIG. As a result, a multi-primary color image signal as shown in FIG. According to this multi-primary color image signal, only virtual pixels corresponding to even columns are lit. Therefore, the luminance reversal phenomenon does not occur.

  FIG. 8 is a diagram illustrating an example of multi-primary color conversion in a case where both odd-numbered pixels and even-numbered columns of pixels in the input image indicate dark skin (that is, when the input image is a solid image of dark skin). is there.

  In this case, in the input image signal, as shown in FIG. 8A, the red, green, and blue luminances (normalized luminances) for both the odd-numbered pixels and the even-numbered pixels are predetermined values larger than zero. Value.

  First, the input image signal is passed through the LPF, and as shown in FIG. 8B, the red, green, and blue luminances are averaged by two pixels. When this signal is converted into multi-primary colors (4-color conversion), there are many combinations of the luminances of the four primary colors for expressing the dark skin. Among them, as shown in FIG. An excellent combination (here, R = 0.42, G = 0.050, B = 0.003, Ye = 0.004) is selected to obtain a multi-primary color signal (low-frequency multi-primary color signal).

  On the other hand, as shown in FIG. 8D, a white component (corresponding to a luminance signal) corresponding to the minimum values of red, green, and blue luminance is extracted from the input image signal. Next, the extracted white component is passed through the HPF and separated into an amount corresponding to an odd number column as shown in FIG. 8 (e) and an amount corresponding to an even number column as shown in FIG. 8 (f). To do. Subsequently, as shown in FIGS. 8G and 8H, each of the separated white components is converted into the luminance of the color of the sub-pixel constituting the corresponding virtual pixel. That is, the white component corresponding to the odd number column is converted into the luminance of the color (red, green, blue) of the sub-pixel constituting the virtual pixel corresponding to the odd number column, and the white component corresponding to the even number example is converted to the even number column. The luminance is converted to the luminance of the color (blue, yellow, red) of the sub-pixel constituting the corresponding virtual pixel. Since the white component corresponding to the odd-numbered column and the white component corresponding to the even-numbered column are not zero, as shown in FIGS. 8G and 8H, the luminance of each color after conversion is not zero. Thereafter, as shown in FIG.

  The luminance after the addition is further added to the low-frequency multi-primary color signal. However, at the time of this addition, the white component extracted from the input image signal is passed through the LPF (see FIG. 8 (j)) is subtracted from the low-frequency multi-primary color signal (see FIG. 8 (k)). The subsequent luminance (here, red, green, and blue are positive and yellow is negative) is added to the luminance shown in FIG. As a result, a multi-primary color image signal as shown in FIG. According to this multi-primary color image signal, both virtual pixels corresponding to odd columns and virtual pixels corresponding to even columns are lit.

  In the example shown in FIG. 8, the brightness of two adjacent pixels is the same on the input side, whereas the brightness of the two virtual pixels is greatly different on the output side. However, since it is a solid image that does not contain high-frequency components, there is no problem. Further, as can be seen from the comparison between FIG. 8C and FIG. 8L, the red, green, blue, and yellow luminances (luminances in FIG. 8L) in the output image signal are excellent in viewing angle characteristics. Therefore, in the example shown in FIG. 8, excellent viewing angle characteristics are maintained.

  FIG. 9 is a diagram illustrating an example of multi-primary color conversion in a case where odd-numbered columns of pixels indicate black and even-numbered columns of pixels indicate dark skin in the input image.

  In this case, in the input image signal, as shown in FIG. 9A, the red, green, and blue luminances (standardized luminance) are zero for the pixels in the odd columns, and the red for the pixels in the even columns. , Green and blue luminances (normalized luminance) are predetermined values larger than zero.

  First, the input image signal is passed through the LPF, and as shown in FIG. 9B, the red, green, and blue luminances are averaged by two pixels. When this signal is converted into multi-primary colors (4-color conversion), as shown in FIG. 9C, a combination with excellent viewing angle characteristics (here, R = 0.42, G = 0.050, B = 0.0). 003, Ye = 0.004) to select a multi-primary color signal (low-frequency multi-primary color signal).

  On the other hand, as shown in FIG. 9D, a white component (corresponding to a luminance signal) corresponding to the minimum values of red, green, and blue luminance is extracted from the input image signal. Next, the extracted white component is passed through the HPF and separated into an amount corresponding to an odd number column as shown in FIG. 9 (e) and an amount corresponding to an even number column as shown in FIG. 9 (f). To do. Subsequently, as shown in FIGS. 9G and 9H, each of the separated white components is converted into the luminance of the color of the sub-pixel constituting the corresponding virtual pixel. That is, the white component corresponding to the odd number column is converted into the luminance of the color (red, green, blue) of the sub-pixel constituting the virtual pixel corresponding to the odd number column, and the white component corresponding to the even number example is converted to the even number column. The luminance is converted to the luminance of the color (blue, yellow, red) of the sub-pixel constituting the corresponding virtual pixel. Since the white component corresponding to the odd-numbered columns is zero, as shown in FIG. 9G, the luminance of each color after conversion is also zero. On the other hand, since the white component corresponding to the even-numbered column is not zero, the luminance of each color after conversion is not zero, as shown in FIG. Thereafter, as shown in FIG. 9I, these are added together.

  The luminance after the addition is further added to the low-frequency multi-primary color signal. However, in this summation, the white component extracted from the input image signal is passed through the LPF (see FIG. 9 (j)) is subtracted from the low-frequency multi-primary color signal (see FIG. 9 (k)). The subsequent luminance (here, red, green, and blue are positive and yellow is negative) is added to the luminance shown in FIG. As a result, a multi-primary color image signal as shown in FIG. According to this multi-primary color image signal, both virtual pixels corresponding to odd columns and virtual pixels corresponding to even columns are lit. Further, the luminance of the virtual pixels corresponding to the odd columns is higher than the luminance of the virtual pixels corresponding to the even columns. As a result, a luminance reversal phenomenon occurs. In this case, as can be seen from the comparison between FIG. 9C and FIG. 9L, the luminances of red, green, blue, and yellow in the output image signal (luminances in FIG. 9L) are the viewing angles. The combination may not be excellent in characteristics (because it is different from the luminance in FIG. 9C), and in the example shown in FIG. 9, the viewing angle characteristic may be deteriorated. However, in the case of a high-frequency image such as a single line illustrated in FIG. 9, even if the viewing angle characteristic is bad, it does not cause a display problem (not so much).

  As described above, in the case of an input image signal as shown in FIG. 9, a luminance reversal phenomenon occurs.

  On the other hand, in the liquid crystal display device 100 of the present embodiment, the low-frequency multi-primary color signal generation unit 21 performs a specific input image signal (one of the two adjacent pixels in the input image indicates a specific color). ), The primary color of the low-frequency component so that the ratio of the absolute luminance of the yellow subpixel Ye to the sum of the absolute luminance of the red subpixel R and the absolute luminance of the green subpixel G is 0.5 or more and 2.0 or less. By performing the conversion, the occurrence of the luminance reversal phenomenon as described above can be prevented. That is, the low-frequency multi-primary color signal generation unit 21 performs low-frequency so that the magnitude relationship between the luminances of two adjacent pixels in the input image is not opposite to the luminance relationship between the two virtual pixels corresponding to the two pixels. Multi-primary colorization of components can be performed.

  Hereinafter, the reason why the occurrence of the luminance reversal phenomenon is prevented will be described based on specific examples. Table 1 below shows red, green, blue, yellow, and pixel P displayed by the red subpixel R, the green subpixel G, the blue subpixel B, and the yellow subpixel Ye of the multi-primary color display panel 10 of the present embodiment. Indicates white chromaticity x, y and tristimulus values X, Y, Z displayed by. FIG. 10 shows the color reproduction range of the multi-primary color display panel 10 of the present embodiment. In FIG. 10, BT. A color gamut of 709 is also shown. Table 2 below shows BT. The chromaticity x, y and tristimulus values X, Y, Z of primary colors (red, green, blue) and white (D65 standard light source) at 709 are shown.

  In the following, a case where one pixel in the input image indicates a dark skin or light skin and the other pixel indicates black is illustrated. The “dark skin” and “light skin” here are dark skin and light skin in Macbeth chart.

  Table 3 below shows the gradations and luminances (normalized luminance) of red, green, and blue when the dark skin is represented by the three primary color image signals, and Table 4 below shows the chromaticity x, y and tristimulus of the dark skin. The values X, Y, Z are shown.

  Table 5 below shows red, green, and blue gradations and luminance (normalized luminance) when the light skin is represented by the three primary color image signals. Table 6 below shows the light skin chromaticity x, y and Tristimulus values X, Y and Z are shown.

  Note that the chromaticity and tristimulus values of the dark skin and light skin may not be exactly the same as those exemplified in Table 4 and Table 6. For example, the chromaticity of the dark skin and light skin may be It may be around 0.02 from the values exemplified in Table 6, and the Y value of the dark skin and light skin may be around 0.005 and 0.01 from the values exemplified in Table 4 and Table 6, respectively. Good.

(Embodiment 1: Dark skin)
Table 7 shows examples (# 1 _{D to} # 10 _D ) of combinations of gradations and luminances of the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye for displaying the dark skin. Show. Table 7 shows two types of luminance, that is, normalized luminance and absolute luminance. The normalized luminance is the luminance normalized with the highest gradation luminance of each color as 1, and the absolute luminance is obtained by multiplying the normalized luminance by the Y value of each color. Table 7 also shows the ratio (R + G: Ye) of the absolute luminance of the red subpixel R and the absolute luminance of the green subpixel G and the absolute luminance of the yellow subpixel Ye for each example. ing. Further, Table 8 shows chromaticity x, y, and Y values when the dark skin is viewed from the front direction, and chromaticity x, y, and Y values when viewed from the oblique 60 ° direction. Table 8 shows chromaticity coordinates (u ′, v ′) indicating chromaticity when the dark skin is viewed from the front direction and chromaticity coordinates (u ′) indicating chromaticity when viewed from the oblique 60 ° direction. ₆₀ ', v ₆₀ ') and the color difference Δu'v '(= ((u'-u ₆₀ ') ² + (v'-v ₆₀ ') ² ) ^1/2 ) is also shown Yes.

In the liquid crystal display device 100 according to the present embodiment, the low-frequency multi-primary color signal generation unit 21 performs the absolute luminance and green sub-pixels of the red sub-pixel R when one of the two adjacent pixels in the input image indicates a dark skin. The low primary component multi-primary color is formed so that the ratio of the absolute luminance of the yellow sub-pixel Ye to the sum of the absolute luminances of the pixels G is 0.5 or more and 2.0 or less. In other words, among the combinations shown in Table 7, the first and eighth to tenth combination _{(♯1 D, ♯8 D ~♯10 D} ) rather than 2 to seventh combination (# 2 _D -# 7 _D ) Multi-primary colors are selected.

(Embodiment 2: Light skin)
Table 9 shows examples (# 1 _{L to} # 11 _L ) of combinations of gradations and luminances of the red sub-pixel R, the green sub-pixel G, the blue sub-pixel B, and the yellow sub-pixel Ye for displaying the light skin. Show. Table 9 shows two types of luminance, normalized luminance and absolute luminance. Table 9 also shows the ratio (R + G: Ye) of the absolute luminance of the red subpixel R and the absolute luminance of the green subpixel G and the absolute luminance of the yellow subpixel Ye for each example. ing. Further, Table 10 shows chromaticity x, y, and Y values when the light skin is viewed from the front direction, and chromaticity x, y, and Y values when viewed from the oblique 60 ° direction. Table 10 shows chromaticity coordinates (u ′, v ′) indicating chromaticity when the light skin is viewed from the front direction and chromaticity coordinates (u ′) indicating chromaticity when viewed from the oblique 60 ° direction. ₆₀ ', v ₆₀ ') and the color difference Δu'v '(= ((u'-u ₆₀ ') ² + (v'-v ₆₀ ') ² ) ^1/2 ) is also shown Yes.

In the liquid crystal display device 100 according to the present embodiment, the low-frequency multi-primary color signal generation unit 21 performs the absolute luminance and green sub-range of the red sub-pixel R when one of the two adjacent pixels in the input image indicates a light skin. The low primary component multi-primary color is formed so that the ratio of the absolute luminance of the yellow sub-pixel Ye to the sum of the absolute luminances of the pixels G is 0.5 or more and 2.0 or less. That is, of the combinations shown in Table 9, the third to ninth, not the first, second, tenth and eleventh combinations (# 1 _L , # 2 _L , # 10 _L , # 11 _L ) performing Tahara coloring to select th combining (♯3 _L ~♯9 _L).

By performing multi-primary color conversion as described above, it is possible to prevent the occurrence of a luminance reversal phenomenon. Hereinafter, this is shown by the fifth, seventh, and second combinations (# 5 _D , # 7 _D , # 2 _D ; shown in Table 7; hereinafter, Example 1, Example 2, Example 3 respectively) Will be described in more detail.

  FIG. 11 is a diagram illustrating an example of multi-primary color conversion in a case where odd-numbered columns of pixels indicate black and even-numbered columns of pixels indicate dark skin in the input image.

  In this case, in the input image signal, as shown in FIG. 11A, the red, green, and blue luminances (normalized luminances) are zero for the odd-numbered pixels, and the red for the even-numbered pixels. , Green and blue luminances (normalized luminance) are predetermined values larger than zero. Here, the maximum value of the luminances of red, green, and blue in the even-numbered pixels is 0.123.

  First, the input image signal is passed through the LPF, and as shown in FIG. 11B, the red, green, and blue luminances are averaged by two pixels. When this signal is converted into multiple primary colors (4-color conversion), as shown in FIG. 11C, the absolute luminance of the yellow sub-pixel Ye with respect to the sum of the absolute luminance of the red sub-pixel R and the absolute luminance of the green sub-pixel G. Example 1 (R = 0.033, G = 0.015, B = 0.005, Ye = 0.048) which is a combination in which the ratio is 1 (that is, a combination of R + G: Ye = 1: 1) is selected. Then, a multi-primary color signal (low-frequency multi-primary color signal) is obtained.

  On the other hand, as shown in FIG. 11D, a white component (corresponding to a luminance signal) corresponding to the minimum values of red, green, and blue luminance is extracted from the input image signal. Here, the luminance of the white component (normalized luminance) is 0.044 (about 1/3 of the maximum luminance). Next, the extracted white component is passed through the HPF and separated into an amount corresponding to an odd number column as shown in FIG. 11 (e) and an amount corresponding to an even number column as shown in FIG. 11 (f). To do. Subsequently, as shown in FIGS. 11G and 11H, each of the separated white components is converted into the luminance of the color of the sub-pixel constituting the corresponding virtual pixel. That is, the white component corresponding to the odd number column is converted into the luminance of the color (red, green, blue) of the sub-pixel constituting the virtual pixel corresponding to the odd number column, and the white component corresponding to the even number example is converted to the even number column. The luminance is converted to the luminance of the color (blue, yellow, red) of the sub-pixel constituting the corresponding virtual pixel. Since the white component corresponding to the odd-numbered column is zero, as shown in FIG. 11G, the luminance of each color after conversion is also zero. On the other hand, the white components corresponding to the even columns are not zero, and as shown in FIG. 11 (h), the luminances (absolute luminances) of blue, yellow, and red after conversion are 0.024, 0.042, 0.003. Thereafter, as shown in FIG.

  The luminance after the addition is further added to the low-frequency multi-primary color signal. However, at the time of this addition, the white component extracted from the input image signal is passed through the LPF (as shown in FIG. 11 (j), converted into absolute brightness of red, green, blue, and yellow, 0.007 respectively. , 0.014, 0.004, 0.019) are subtracted from the low-frequency multi-primary color signal, and the luminance after the subtraction (as shown in FIG. 11 (k), here, red, green, blue, yellow are 0 respectively) .026, 0.001, 0.001, 0.029) are added to the luminance shown in FIG. As a result, a multi-primary image signal (R = 0.026 + (0.003), G = 0.001, B = 0.025, Ye = 0.071) as shown in FIG. . According to this multi-primary color image signal, both virtual pixels corresponding to odd columns and virtual pixels corresponding to even columns are lit. Further, the yellow sub-pixel Ye is higher than the sum of the luminance of the red sub-pixel R and the luminance of the green sub-pixel (= 0.027; excluding the luminance (= 0.003) of the red sub-pixel R of the adjacent pixel P). As can be seen from the higher luminance (= 0.071), the luminance of the virtual pixels corresponding to the even columns is higher than the luminance of the virtual pixels corresponding to the odd columns. Therefore, the luminance reversal phenomenon does not occur.

  FIG. 12 is a diagram illustrating an example of multi-primary color conversion in a case where odd-numbered columns of pixels indicate black and even-numbered columns of pixels indicate dark skin in the input image.

  In this case, in the input image signal, as shown in FIG. 12A, the red, green, and blue luminances (standardized luminance) are zero for the odd-numbered pixels, and the red for the even-numbered pixels. , Green and blue luminances (normalized luminance) are predetermined values larger than zero. Here, the maximum value of the luminances of red, green, and blue in the even-numbered pixels is 0.123.

  First, the input image signal is passed through the LPF, and as shown in FIG. 12B, the red, green, and blue luminances are averaged by two pixels. When this signal is converted into multiple primary colors (4-color conversion), as shown in FIG. 12C, the absolute luminance of the yellow sub-pixel Ye with respect to the sum of the absolute luminance of the red sub-pixel R and the absolute luminance of the green sub-pixel G. Example 2 (R = 0.036, G = 0.027, B = 0.005, Ye = 0.0) which is a combination in which the ratio is 0.5 (that is, a combination of R + G: Ye = 1: 0.5). 033) is selected to obtain a multi-primary color signal (low-frequency multi-primary color signal).

  On the other hand, as shown in FIG. 12D, a white component (corresponding to a luminance signal) corresponding to the minimum values of red, green, and blue luminance is extracted from the input image signal. Here, the luminance of the white component (normalized luminance) is 0.044 (about 1/3 of the maximum luminance). Next, the extracted white component is passed through the HPF and separated into an amount corresponding to an odd number column as shown in FIG. 12 (e) and an amount corresponding to an even number column as shown in FIG. 12 (f). To do. Subsequently, as shown in FIGS. 12G and 12H, each of the separated white components is converted into the luminance of the color of the sub-pixel constituting the corresponding virtual pixel. That is, the white component corresponding to the odd number column is converted into the luminance of the color (red, green, blue) of the sub-pixel constituting the virtual pixel corresponding to the odd number column, and the white component corresponding to the even number example is converted to the even number column. The luminance is converted to the luminance of the color (blue, yellow, red) of the sub-pixel constituting the corresponding virtual pixel. Since the white component corresponding to the odd-numbered columns is zero, as shown in FIG. 12G, the luminance of each color after conversion is also zero. On the other hand, the white components corresponding to the even columns are not zero, and the luminances (absolute luminances) of blue, yellow, and red after conversion are 0.024, 0.042, respectively, as shown in FIG. 0.003. Thereafter, as shown in FIG.

  The luminance after the addition is further added to the low-frequency multi-primary color signal. However, at the time of this addition, the white component extracted from the input image signal is passed through the LPF (as shown in FIG. 12 (j), converted into absolute luminances of red, green, blue and yellow, 0.007 respectively. , 0.014, 0.004, 0.019) are subtracted from the low-frequency multi-primary color signal, and the luminance after subtraction (as shown in FIG. 12 (k), red, green, blue, and yellow are 0 here). .029, 0.013, 0.001, 0.014) is added to the luminance shown in FIG. As a result, a multi-primary color image signal (R = 0.029 + (0.003), G = 0.013, B = 0.025, Ye = 0.056) as shown in FIG. . According to this multi-primary color image signal, both virtual pixels corresponding to odd columns and virtual pixels corresponding to even columns are lit. Further, as can be seen from the fact that the luminance of the yellow sub-pixel Ye (= 0.056) is higher than the sum of the luminance of the red sub-pixel R and the luminance of the green sub-pixel (= 0.042), The brightness of the virtual pixels corresponding to the even columns is higher than the brightness of the corresponding virtual pixels. Therefore, the luminance reversal phenomenon does not occur.

  FIG. 13 is a diagram illustrating an example of multi-primary color conversion in a case where odd-numbered pixels in the input image indicate dark skin and even-numbered pixels indicate black.

  In this case, in the input image signal, as shown in FIG. 13A, for the pixels in the odd-numbered columns, the red, green, and blue luminances (standardized luminance) are predetermined values larger than zero, For these pixels, the luminance of red, green and blue (normalized luminance) is zero. Here, the maximum value of the luminances of red, green, and blue in the odd-numbered pixels is 0.123.

  First, the input image signal is passed through the LPF, and as shown in FIG. 13B, the red, green, and blue luminances are averaged by two pixels. When this signal is converted into multiple primary colors (4-color conversion), as shown in FIG. 13C, the absolute luminance of the yellow subpixel Ye with respect to the sum of the absolute luminance of the red subpixel R and the absolute luminance of the green subpixel G is calculated. Example 3 (R = 0.029, G = 0.003, B = 0.005, Ye = 0.064) which is a combination in which the ratio is 2 (that is, a combination of R + G: Ye = 1: 2) is selected. Then, a multi-primary color signal (low-frequency multi-primary color signal) is obtained.

  On the other hand, as shown in FIG. 13D, a white component (corresponding to a luminance signal) corresponding to the minimum values of red, green, and blue luminance is extracted from the input image signal. Here, the luminance of the white component (normalized luminance) is 0.044 (about 1/3 of the maximum luminance). Next, the extracted white component is passed through the HPF and separated into an amount corresponding to an odd number column as shown in FIG. 13 (e) and an amount corresponding to an even number column as shown in FIG. 13 (f). To do. Subsequently, as shown in FIGS. 13G and 13H, each of the separated white components is converted into the luminance of the color of the sub-pixel constituting the corresponding virtual pixel. That is, the white component corresponding to the odd number column is converted into the luminance of the color (red, green, blue) of the sub-pixel constituting the virtual pixel corresponding to the odd number column, and the white component corresponding to the even number example is converted to the even number column. The luminance is converted to the luminance of the color (blue, yellow, red) of the sub-pixel constituting the corresponding virtual pixel. The white components corresponding to the odd columns are not zero, and the red, green, and blue luminances (absolute luminances) after conversion are 0.012, 0.032, and 0.003, respectively, as shown in FIG. is there. On the other hand, since the white component corresponding to the even-numbered columns is zero, the luminance of each color after conversion is also zero as shown in FIG. Thereafter, as shown in FIG.

  The luminance after the addition is further added to the low-frequency multi-primary color signal. However, at the time of this addition, the white component extracted from the input image signal is passed through the LPF (as shown in FIG. 13 (j), converted into absolute luminances of red, green, blue, and yellow, 0.007 respectively. , 0.014, 0.004, 0.019) is subtracted from the low-frequency multi-primary color signal, and the luminance after subtraction (as shown in FIG. 13 (k), red, green, blue, and yellow are 0 here). .022, -0.011, 0.001, 0.045) is added to the luminance shown in FIG. As a result, a multi-primary color image signal (R = 0.031, G = 0.021, B = 0.004, Ye = 0.045) as shown in FIG. According to this multi-primary color image signal, both virtual pixels corresponding to odd columns and virtual pixels corresponding to even columns are lit. Further, as can be seen from the fact that the luminance of the yellow sub-pixel Ye (= 0.045) is lower than the sum of the luminance of the red sub-pixel R and the luminance of the green sub-pixel (= 0.052), The brightness of the virtual pixels corresponding to the even columns is lower than the brightness of the corresponding virtual pixels. Therefore, the luminance reversal phenomenon does not occur.

  As described above, when the low frequency multi-primary color signal generation unit 21 of the signal conversion circuit 20 selects the combination of the luminances of the first, second, or third embodiment, the occurrence of the luminance reversal phenomenon can be prevented.

On the other hand, for example, when the ninth combination (# 9 _D ; hereinafter referred to as a comparative example) in Table 7 is selected, a luminance reversal phenomenon occurs.

  FIG. 14 is a diagram illustrating an example of multi-primary color conversion in a case where odd-numbered columns of pixels indicate black and even-numbered columns of pixels indicate dark skin in the input image.

  In this case, in the input image signal, as shown in FIG. 14A, the red, green, and blue luminances (standardized luminance) are zero for the odd-numbered pixels, and the red for the even-numbered pixels. , Green and blue luminances (normalized luminance) are predetermined values larger than zero. Here, the maximum value of the luminances of red, green, and blue in the even-numbered pixels is 0.123.

  First, the input image signal is passed through the LPF, and as shown in FIG. 14B, the red, green, and blue luminances are averaged by two pixels. When this signal is converted into multiple primary colors (4-color conversion), as shown in FIG. 14C, the absolute luminance of the yellow subpixel Ye with respect to the sum of the absolute luminance of the red subpixel R and the absolute luminance of the green subpixel G is calculated. Comparative example (R = 0.042, G = 0.054, B = 0.005, Ye = 0.001) which is a combination in which the ratio is 0.01 (that is, a combination of R + G: Ye = 1: 0.01). ) To obtain a multi-primary color signal (low-frequency multi-primary color signal).

  On the other hand, as shown in FIG. 14D, a white component (corresponding to a luminance signal) corresponding to the minimum values of red, green, and blue luminance is extracted from the input image signal. Here, the luminance of the white component (normalized luminance) is 0.044 (about 1/3 of the maximum luminance). Next, the extracted white component is passed through the HPF and separated into an amount corresponding to an odd number column as shown in FIG. 14 (e) and an amount corresponding to an even number column as shown in FIG. 14 (f). To do. Subsequently, as shown in FIGS. 14G and 14H, each of the separated white components is converted into the luminance of the color of the sub-pixel constituting the corresponding virtual pixel. That is, the white component corresponding to the odd number column is converted into the luminance of the color (red, green, blue) of the sub-pixel constituting the virtual pixel corresponding to the odd number column, and the white component corresponding to the even number example is converted to the even number column. The luminance is converted to the luminance of the color (blue, yellow, red) of the sub-pixel constituting the corresponding virtual pixel. Since the white component corresponding to the odd-numbered columns is zero, as shown in FIG. 14G, the luminance of each color after conversion is also zero. On the other hand, the white components corresponding to the even columns are not zero, and as shown in FIG. 14 (h), the luminances (absolute luminances) of blue, yellow, and red after conversion are 0.024, 0.042, 0.003. Thereafter, as shown in FIG. 14 (i), these are added together.

  The luminance after the addition is further added to the low-frequency multi-primary color signal. However, in this summation, the white component extracted from the input image signal is passed through the LPF (as shown in FIG. 14 (j), converted into absolute luminances of red, green, blue, and yellow, 0.007 respectively. , 0.014, 0.004, 0.019) is subtracted from the low-frequency multi-primary color signal, and the luminance after subtraction (as shown in FIG. 14 (k), red, green, blue, and yellow are 0 here). .035, 0.040, 0.001, and -0.018) are added to the luminance shown in FIG. As a result, a multi-primary color image signal (R = 0.035 + (0.003), G = 0.040, B = 0.025, Ye = 0.024) as shown in FIG. . According to this multi-primary color image signal, both virtual pixels corresponding to odd columns and virtual pixels corresponding to even columns are lit. Further, as can be seen from the sum of the luminance of the red sub-pixel R and the luminance of the green sub-pixel (= 0.075) is higher than the luminance of the yellow sub-pixel Ye (= 0.024), The brightness of the virtual pixels corresponding to the odd columns is higher than the brightness of the corresponding virtual pixels. As a result, a luminance reversal phenomenon occurs.

  As described above, in the liquid crystal display device 100 according to the present embodiment, the low-frequency multi-primary color signal generation unit 21 uses the red sub-pixel when one of the two adjacent pixels in the input image shows a specific color. By performing the multi-primary color of the low-frequency component so that the ratio of the absolute luminance of the yellow subpixel Ye to the sum of the absolute luminance of R and the absolute luminance of the green subpixel G is 0.5 or more and 2.0 or less, It is possible to prevent the occurrence of a luminance reversal phenomenon.

  Note that the ratio of the absolute luminance of the yellow subpixel Ye to the sum of the absolute luminance of the red subpixel R and the absolute luminance of the green subpixel G is particularly within the above range (0.5 to 2.0). It is not limited. It may be 1 (or substantially 1) as in the first embodiment, may be 0.5 as in the second embodiment, or may be 2 as in the third embodiment. If the ratio of the absolute luminance of the yellow subpixel Ye to the sum of the absolute luminance of the red subpixel R and the absolute luminance of the green subpixel G is 0.5 or more and 2.0 or less, the white component is 1/3 or more of the total luminance. The luminance reversal phenomenon does not occur for the colors of.

  Here, the significance of the lower limit (0.5) and the upper limit (2.0) of the above range will be described with reference to FIG. FIGS. 15A to 15L are diagrams illustrating an example of multi-primary color conversion in a case where odd-numbered columns of pixels indicate chromatic colors and even-numbered columns of pixels indicate black in the input image. As an example, the relative luminance (normalized luminance) of red and green in the odd-numbered pixels is the same, and the minimum relative luminance is 1/3 with respect to the maximum relative luminance of red, green, and blue. An example is shown. When the minimum value of the relative luminance becomes 1/3 or less of the maximum value, the color component becomes 2 times or more (2/3 or more for 1/3) with respect to the white component. Is distributed evenly, the color component exceeds the white component, making it difficult to obtain the effect of improving the resolution. Therefore, here, an example in which the minimum value of the relative luminance is 1/3 of the maximum value is shown. FIG. 15 shows an example in which the relative luminance of red and green is the same so that the sum of the absolute luminances of red and green becomes the largest after calculation.

  Here, as shown in FIG. 15A, the relative luminance of red and green in the odd-numbered columns of the input image is 1 (reference), and when the white component is extracted as shown in FIG. The (relative luminance) is 0.33. This white component (relative luminance 0.33) is equally distributed to two pixels as shown in FIG. This assumes that when the white component is converted from relative luminance to absolute luminance, red and green and yellow are almost halved (from FIGS. 11 and 12, they are also almost halved). )

  Further, when the low-frequency components are converted into multiple primary colors, as shown in FIG. 15C, a combination in which the ratio of the absolute brightness of yellow to the sum of the absolute brightness of red and green is 2.0 (that is, R + G: Since the combination of Ye = 1: 2 is selected, the absolute luminances are 0.33 and 0.66, respectively. Then, as shown in FIG. 15 (k), 0.33 to 0.15 is subtracted for the pixels in the odd columns, and 0.66 to 0.15 for the pixels in the even columns, as in the previous examples. Therefore, the sum of the absolute luminances of red and green after subtraction is 0.18, and the absolute luminance of yellow is 0.51. When 0.33 (see FIG. 15 (i)) is added to the obtained value for the pixels in the odd-numbered columns, the respective absolute luminances are 0.51 and 0.51, and the luminance reversal phenomenon does not occur. I understand. On the other hand, if the combination of the absolute brightness of yellow to the sum of the absolute brightness of red and the absolute brightness of green is selected when multi-primary colors of low-frequency components are selected, the brightness reversal phenomenon will occur. Will occur. Therefore, the ratio of the absolute luminance of the yellow sub-pixel Ye to the sum of the absolute luminance of the red sub-pixel R and the absolute luminance of the green sub-pixel G is preferably 2.0 or less. For the same reason, if the ratio of the absolute luminance of yellow to the sum of the absolute luminance of red and the absolute luminance of green is less than 0.5, a luminance reversal phenomenon occurs. Therefore, the absolute luminance of the red subpixel R The ratio of the absolute luminance of the yellow sub-pixel Ye to the sum of absolute luminances of the green sub-pixel G is preferably 0.5 or more.

  In the above description, the case where the specific color indicated by one of the two adjacent pixels in the input image is the dark skin or the light skin is illustrated, but of course, the embodiment of the present invention is not limited thereto. Is not to be done. The specific color is typically a chromatic color, and a color whose blue standardized luminance is larger than 1/3 of the larger one of the standardized luminance of red and the standardized luminance of green ( That is, B> MAX (R, G) / 3 color). As can be seen from Table 3, the dark skin is a color in which the normalized luminance of blue is larger than 1/3 of the larger of the normalized luminance of red and the normalized luminance of green (0.092> 0). .267 / 3). In addition, as can be seen from Table 5, the light skin also has a color whose blue standardized luminance is larger than 1/3 of the larger one of the standardized luminance of red and the standardized luminance of green (0.311). > 0.632 / 3).

  In the above description, the case where the color indicated by the other of the two adjacent pixels in the input image is black is exemplified, but the embodiment of the present invention is not limited to this. The color indicated by the other pixel may be the specific color. That is, the input image may be a solid image of the specific color.

From the viewpoint of realizing a high viewing angle characteristic, the low-frequency multi-primary color signal generation unit 21 determines the color represented by the low-frequency multi-primary color signal from the front direction when one pixel in the input image indicates a specific color. chromaticity coordinates (u ', v') showing the chromaticity when viewed with the color difference is defined by the chromaticity coordinates indicating the chromaticity when viewed from a 60 ° oblique direction _{(u 60 ', v 60'} ) Δu′v ′ (= ((u′−u ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) It is preferable to perform multi-primary color so that ^1/2 is 0.03 or less. The second to sixth combinations (# 2 _{D to} # 6 _D ) in Table 8 and the third to ninth combinations (# 3 _{L to} # 9 _L ) in Table 9 and Table 10 satisfy this condition. doing.

From the same viewpoint, when one pixel in the input image indicates a dark skin, the low-frequency multi-primary color signal generation unit 21 determines the chromaticity when the color represented by the low-frequency multi-primary color signal is viewed from the front direction. The color difference Δu′v ′ defined by the chromaticity coordinates (u ′, v ′) shown and the chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) showing the chromaticity when viewed from an oblique 60 ° direction is 0. It is preferable to perform multi-primary color so as to be 03 or less. The second to sixth combinations (# 2 _{D to} # 6 _D ) in Tables 7 and 8 satisfy this condition.

From the same viewpoint, when one pixel in the input image indicates a light skin, the low frequency multi-primary color signal generation unit 21 calculates chromaticity when the color represented by the low frequency multi-primary color signal is viewed from the front direction. The color difference Δu′v ′ defined by the chromaticity coordinates (u ′, v ′) shown and the chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) showing the chromaticity when viewed from an oblique 60 ° direction is 0. It is preferable to perform multi-primary color so as to be 01 or less. The third to ninth combinations (# 3 _{L to} # 9 _L ) in Table 9 and Table 10 satisfy this condition.

  This specification discloses the multi-primary color display device described in the following items.

[Item 1]
A multi-primary color display device having a pixel composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a yellow sub-pixel, and performing color display using four primary colors of red, green, blue, and yellow,
A multi-primary color display panel having the red sub-pixel, the green sub-pixel, the blue sub-pixel and the yellow sub-pixel in each pixel;
A signal conversion circuit that converts an input image signal corresponding to three primary colors into a multi-primary color image signal corresponding to the four primary colors;
The red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel constituting the pixel are divided into two virtual pixels, and display of two adjacent pixels in the input image is performed by the two virtual pixels. It is possible,
The signal conversion circuit includes:
A low-frequency multi-primary color signal generation unit that generates a low-frequency multi-primary color signal based on the input image signal, wherein the low-frequency component of the input image signal is a multi-primary signal;
Based on the input image signal, a high-frequency luminance signal generating unit that generates a high-frequency luminance signal that is a signal obtained by luminance conversion of the high-frequency component of the input image signal;
A rendering processing unit that performs rendering processing on the two virtual pixels based on the low-frequency multi-primary color signal and the high-frequency luminance signal;
The low-frequency multi-primary color signal generator generates a sum of absolute luminance of the red sub-pixel and absolute luminance of the green sub-pixel when one of the two adjacent pixels in the input image indicates a specific color. A multi-primary color display device capable of performing multi-primary coloration of the low-frequency component so that a ratio of absolute luminance of the yellow sub-pixel to 0.5 to 2.0 is achieved.

[Item 2]
The specific color is a chromatic color, and the standardized luminance of blue is a color larger than 1/3 of the larger one of the normalized luminance of red and the normalized luminance of green. Multi-primary color display device.

[Item 3]
When the one pixel in the input image indicates the specific color, the low-frequency multi-primary color signal generator generates the yellow sub-pixel with respect to the sum of the absolute luminance of the red sub-pixel and the absolute luminance of the green sub-pixel. 3. The multi-primary color display device according to item 1 or 2, wherein the multi-primary color can be changed so that the absolute luminance ratio is substantially 1.

[Item 4]
When the one pixel in the input image indicates the specific color, the low-frequency multi-primary color signal generation unit is a color indicating chromaticity when the color represented by the low-frequency multi-primary color signal is viewed from the front direction. The color difference Δu′v ′ = ((u ′, v ′) and the chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) indicating the chromaticity when viewed obliquely from 60 °. -u ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) The multi-primary color display device according to any one of items 1 to 3, capable of performing multi-primary color so that ^1/2 is 0.03 or less .

[Item 5]
The specific color is a dark skin;
The low-frequency multi-primary color signal generation unit, when the one pixel in the input image indicates a dark skin, chromaticity coordinates indicating chromaticity when the color represented by the low-frequency multi-primary color signal is viewed from the front direction Color difference Δu′v ′ = ((u′−u) defined by (u ′, v ′) and chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) indicating chromaticity when viewed from an oblique 60 ° direction ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) The multi-primary color display device according to any one of items 1 to 4, which can perform multi-primary color so that ^1/2 is 0.03 or less.

[Item 6]
The specific color is light skin,
The low-frequency multi-primary color signal generation unit, when the one pixel in the input image indicates a light skin, chromaticity coordinates indicating chromaticity when the color represented by the low-frequency multi-primary color signal is viewed from the front direction Color difference Δu′v ′ = ((u′−u) defined by (u ′, v ′) and chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) indicating chromaticity when viewed from an oblique 60 ° direction ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) The multi-primary color display device according to any one of items 1 to 5, which can be multi-primary so that ^1/2 is 0.01 or less.

[Item 7]
The multi-primary color display device according to any one of items 1 to 6, wherein when one of the two adjacent pixels in the input image shows a specific color, the other pixel shows black.

[Item 8]
Each of the two virtual pixels is any one of items 1 to 7 including two or more subpixels of the red subpixel, the green subpixel, the blue subpixel, and the yellow subpixel. Multi-primary color display device.

[Item 9]
A plurality of the pixels are arranged in a matrix including a plurality of rows and a plurality of columns,
The multi-primary color according to any one of items 1 to 8, wherein, in each of the plurality of pixels, the red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel are arranged in one row and four columns. Display device.

[Item 10]
The multi-primary color display device according to any one of items 1 to 9, which is a liquid crystal display device.

[Item 11]
A multi-primary color display device having a pixel composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a yellow sub-pixel, and performing color display using four primary colors of red, green, blue, and yellow,
A multi-primary color display panel having the red sub-pixel, the green sub-pixel, the blue sub-pixel and the yellow sub-pixel in each pixel;
A signal conversion circuit that converts an input image signal corresponding to three primary colors into a multi-primary color image signal corresponding to the four primary colors;
The red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel constituting the pixel are divided into two virtual pixels, and display of two adjacent pixels in the input image is performed by the two virtual pixels. It is possible,
The signal conversion circuit includes:
A low-frequency multi-primary color signal generation unit that generates a low-frequency multi-primary color signal based on the input image signal, wherein the low-frequency component of the input image signal is a multi-primary signal;
Based on the input image signal, a high-frequency luminance signal generating unit that generates a high-frequency luminance signal that is a signal obtained by luminance conversion of the high-frequency component of the input image signal;
A rendering processing unit that performs rendering processing on the two virtual pixels based on the low-frequency multi-primary color signal and the high-frequency luminance signal;
The low-frequency multi-primary color signal generation unit includes a magnitude relationship between luminances of one pixel and the other pixel of the two adjacent pixels in the input image, a virtual pixel corresponding to the one pixel, and the other pixel. A multi-primary color display device capable of performing multi-primary coloration of the low-frequency component so that the magnitude relationship of the luminance of the virtual pixels corresponding to is not reversed.

  According to the embodiment of the present invention, in a multi-primary color display device capable of improving the resolution by display using virtual pixels, it is possible to prevent the occurrence of a luminance reversal phenomenon between the input side and the output side.

  Since the multi-primary color display device according to the embodiment of the present invention can perform high-quality display, the multi-primary color display device is suitably used for various electronic devices such as a liquid crystal television.

DESCRIPTION OF SYMBOLS 10 Multi primary color display panel 20 Signal conversion circuit 21 Low frequency multi primary color signal generation part 22 High frequency luminance signal generation part 23 Rendering processing part 24 γ correction part 25 Inverse γ correction part 26 Low frequency component extraction part (low-pass filter)
27 Multi-primary color conversion unit 28 Luminance conversion unit 29 High-frequency component extraction unit (high-pass filter)
100 Liquid crystal display device (multi-primary color display device)
P pixel R red sub-pixel G green sub-pixel B blue sub-pixel Ye yellow sub-pixel VP1 first virtual pixel VP2 second virtual pixel

Claims (11)

A multi-primary color display device having a pixel composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a yellow sub-pixel, and performing color display using four primary colors of red, green, blue, and yellow,
A multi-primary color display panel having the red sub-pixel, the green sub-pixel, the blue sub-pixel and the yellow sub-pixel in each pixel;
A signal conversion circuit that converts an input image signal corresponding to three primary colors into a multi-primary color image signal corresponding to the four primary colors;
The red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel constituting the pixel are divided into two virtual pixels, and display of two adjacent pixels in the input image is performed by the two virtual pixels. It is possible,
The signal conversion circuit includes:
A low-frequency multi-primary color signal generation unit that generates a low-frequency multi-primary color signal based on the input image signal, wherein the low-frequency component of the input image signal is a multi-primary signal;
Based on the input image signal, a high-frequency luminance signal generating unit that generates a high-frequency luminance signal that is a signal obtained by luminance conversion of the high-frequency component of the input image signal;
A rendering processing unit that performs rendering processing on the two virtual pixels based on the low-frequency multi-primary color signal and the high-frequency luminance signal;
The low-frequency multi-primary color signal generator generates a sum of absolute luminance of the red sub-pixel and absolute luminance of the green sub-pixel when one of the two adjacent pixels in the input image indicates a specific color. A multi-primary color display device capable of performing multi-primary coloration of the low-frequency component so that a ratio of absolute luminance of the yellow sub-pixel to 0.5 to 2.0 is achieved.   The specific color is a chromatic color, and a standardized luminance of blue is a color larger than 1/3 of a larger one of the standardized luminance of red and the standardized luminance of green. The multi-primary color display device described.   When the one pixel in the input image indicates the specific color, the low-frequency multi-primary color signal generator generates the yellow sub-pixel with respect to the sum of the absolute luminance of the red sub-pixel and the absolute luminance of the green sub-pixel. The multi-primary color display device according to claim 1, wherein the multi-primary color display can be performed so that the absolute luminance ratio is substantially 1. When the one pixel in the input image indicates the specific color, the low-frequency multi-primary color signal generation unit is a color indicating chromaticity when the color represented by the low-frequency multi-primary color signal is viewed from the front direction. The color difference Δu′v ′ = ((u ′, v ′) and the chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) indicating the chromaticity when viewed obliquely from 60 °. The multi-primary color display device according to any one of claims 1 to 3, wherein the multi-primary color can be formed so that -u ₆₀ ') ² + (v'-v ₆₀ ') ² ) ^1/2 is 0.03 or less. . The specific color is a dark skin;
The low-frequency multi-primary color signal generation unit, when the one pixel in the input image indicates a dark skin, chromaticity coordinates indicating chromaticity when the color represented by the low-frequency multi-primary color signal is viewed from the front direction Color difference Δu′v ′ = ((u′−u) defined by (u ′, v ′) and chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) indicating chromaticity when viewed from an oblique 60 ° direction The multi-primary color display device according to claim 1, wherein the multi-primary color can be formed so that ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) ^1/2 is 0.03 or less. The specific color is light skin,
The low-frequency multi-primary color signal generation unit, when the one pixel in the input image indicates a light skin, chromaticity coordinates indicating chromaticity when the color represented by the low-frequency multi-primary color signal is viewed from the front direction Color difference Δu′v ′ = ((u′−u) defined by (u ′, v ′) and chromaticity coordinates (u ₆₀ ′, v ₆₀ ′) indicating chromaticity when viewed from an oblique 60 ° direction The multi-primary color display device according to claim 1, wherein the multi-primary color can be formed so that ₆₀ ′) ² + (v′−v ₆₀ ′) ² ) ^1/2 is 0.01 or less.   The multi-primary color display device according to any one of claims 1 to 6, wherein when one of the two adjacent pixels in the input image shows a specific color, the other pixel shows black.   Each of the two virtual pixels is configured by two or more subpixels of the red subpixel, the green subpixel, the blue subpixel, and the yellow subpixel. The multi-primary color display device described. A plurality of the pixels are arranged in a matrix including a plurality of rows and a plurality of columns,
9. The multi-pixel according to claim 1, wherein in each of the plurality of pixels, the red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel are arranged in one row and four columns. Primary color display device.   The multi-primary color display device according to claim 1, which is a liquid crystal display device. A multi-primary color display device having a pixel composed of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a yellow sub-pixel, and performing color display using four primary colors of red, green, blue, and yellow,
A multi-primary color display panel having the red sub-pixel, the green sub-pixel, the blue sub-pixel and the yellow sub-pixel in each pixel;
A signal conversion circuit that converts an input image signal corresponding to three primary colors into a multi-primary color image signal corresponding to the four primary colors;
The red sub-pixel, the green sub-pixel, the blue sub-pixel, and the yellow sub-pixel constituting the pixel are divided into two virtual pixels, and display of two adjacent pixels in the input image is performed by the two virtual pixels. It is possible,
The signal conversion circuit includes:
A low-frequency multi-primary color signal generation unit that generates a low-frequency multi-primary color signal based on the input image signal, wherein the low-frequency component of the input image signal is a multi-primary signal;
Based on the input image signal, a high-frequency luminance signal generating unit that generates a high-frequency luminance signal that is a signal obtained by luminance conversion of the high-frequency component of the input image signal;
A rendering processing unit that performs rendering processing on the two virtual pixels based on the low-frequency multi-primary color signal and the high-frequency luminance signal;
The low-frequency multi-primary color signal generation unit includes a magnitude relationship between luminances of one pixel and the other pixel of the two adjacent pixels in the input image, a virtual pixel corresponding to the one pixel, and the other pixel. A multi-primary color display device capable of performing multi-primary coloration of the low-frequency component so that the magnitude relationship of the luminance of the virtual pixels corresponding to is not reversed.

Images