Image display unit, method of driving image display unit, signal generator, signal generation program, and signal generation method

A method of driving an image display unit with an image display section and a signal generating section,

• the image display section having pixels arranged two-dimensionally in a matrix pattern, the pixels each including a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel, and
• the signal generating section being configured to generate a red sub-pixel signal, a green sub-pixel signal, a blue sub-pixel signal, and a white sub-pixel signal, based on a red-display image signal, a green-display image signal, and a blue-display image signal that are provided in accordance with an image to be displayed,
• the method comprising:
• allowing the signal generating section to determine values of the red sub-pixel signal Rcvt, the green sub-pixel signal Gcvt, and the blue sub-pixel signal Bcvt, based on a first matrix and a second matrix, with use of a coefficient ‘Purity’, an additive-color-mixture matrix, and a purity coefficient ‘Ψ’, and
• allowing the signal generating section to employ a value of the white sub-pixel signal Wcvt as a value of min (RnL, GnL, BnL), where the min (RnL, GnL, BnL) represents a minimum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL that are linearized and normalized and are provided for each of the pixels,
• the coefficient ‘Purity’ being defined by a value obtained through subtracting the min (RnL, GnL, BnL) from max (RnL, GnL, BnL), where the max (RnL, GnL, BnL) represents a maximum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL,
• the additive-color-mixture matrix being defined in accordance with specification of the image to be displayed, a product of the additive-color-mixture matrix and a three-rows-one-column matrix sed of the signals (RnL, GnL, BnL) resulting in a three-rows-one-column matrix composed of tristimulus values,
• the purity coefficient ‘Ψ’ having a value that varies to approach a value ‘TH1’ with an increase in a value of the coefficient ‘Purity’ and varies to approach a value ‘1’ with a decrease in the value of the coefficient ‘Purity’, the value ‘TH1’ representing a ratio given by an expression of WR+G+B—max/(WR+G+B—max+WW—max), where the parameter ‘WR+G+B—max’ represents designed maximum white luminance that is realized with the red sub-pixel, the green sub-pixel, and the blue sub-pixel in a pixel of the pixels, and the parameter ‘WW—max’ represents designed maximum white luminance that is realized with the white sub-pixel in the pixel of the pixels,
• the first matrix being configured of a difference obtained through subtracting first tristimulus values from second tristimulus values, the first tristimulus values being a product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL) when all of the values of the signals (RnL, GnL, BnL) are min (RnL, GnL, BnL), and the second tristimulus values being obtained through multiplying the purity coefficient ‘Ψ’ by the product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL), and
• the second matrix being an inverse matrix of a matrix obtained through multiplying the additive-color-mixture matrix by ‘TH1’.

A non-transitory tangible recording medium having a computer-readable program embodied therein, the computer-readable program allowing, when executed by an signal generator, the signal generator to perform data processing, the signal generator being configured to generate a red sub-pixel signal, a green sub-pixel signal, a blue sub-pixel signal, and a white sub-pixel signal, based on a red-display image signal, a green-display image signal, and a blue-display image signal that are provided in accordance with an image to be displayed,

• the data processing comprising:
• allowing the signal generator to determine values of the red sub-pixel signal Rcvt, the green sub-pixel signal Gcvt, and the blue sub-pixel signal Bcvt, based on a first matrix and a second matrix, with use of a coefficient ‘Purity’, an additive-color-mixture matrix, and a purity coefficient ‘Ψ’, and
• allowing the signal generator to employ a value of the white sub-pixel signal Wcvt as a value of min (RnL, GnL, BnL), where the min (RnL, GnL, BnL) represents a minimum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL that are linearized and normalized and are provided for each of the pixels,
• the coefficient ‘Purity’ being defined by a value obtained through subtracting the min (RnL, BnL) from max (RnL, GnL, BnL), where the max (RnL, GnL, BnL) represents a maximum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL,
• the additive-color-mixture matrix being defined in accordance with specification of the image to be displayed, a product of the additive-color-mixture matrix and a three-rows-one-column matrix composed of the signals (RnL, GnL, BnL) resulting in a three-rows-one-column matrix composed of tristimulus values,
• the purity coefficient ‘Ψ’ having a value that varies to approach a value ‘TH1’ with an increase in a value of the coefficient ‘Purity’ and varies to approach a value ‘1’ with a decrease in the value of the coefficient ‘Purity’, the value ‘TH1’ representing a ratio given by an expression of WR+G+B—max/(WR+G+B—max+WW—max), where the parameter ‘WR+G+B—max’ represents designed maximum white luminance that is realized with the red sub-pixel, the green sub-pixel, and the blue sub-pixel in a pixel of the pixels, and the parameter ‘WW—max’ represents designed maximum white luminance that is realized with the white sub-pixel in the pixel of the pixels,
• the first matrix being configured of a difference obtained through subtracting first tristimulus values from second tristimulus values, the first tristimulus values being a product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL) when all of the values of the signals (RnL, GnL, BnL) are min (RnL, GnL, BnL), and the second tristimulus values being obtained through multiplying the purity coefficient ‘Ψ’ by the product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL), and
• the second matrix being an inverse matrix of a matrix obtained through multiplying the additive-color-mixture matrix by ‘TH1’.

A signal generator comprising a signal generating section configured to generate a red sub-pixel signal, a green sub-pixel signal, a blue sub-pixel signal, and a white sub-pixel signal, based on a red-display image signal, a green-display image signal, and a blue-display image signal that are provided in accordance with an image to be displayed,

• the signal generating section being configured to determine values of the red sub-pixel signal Rcvt, the green sub-pixel signal Gcvt, and the blue sub-pixel signal Bcvt, based on a first matrix and a second matrix, with use of a coefficient ‘Purity’, an additive-color-mixture matrix, and a purity coefficient ‘Ψ’, and being configured to employ a value of the white sub-pixel signal Wcvt as a value of min (RnL, GnL, BnL), where the min (RnL, GnL, BnL) represents a minimum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL that are linearized and normalized and are provided for each of the pixels,
• the coefficient ‘Purity’ being defined by a value obtained through subtracting the min (RnL, GnL, BnL) from max (RnL, GnL, BnL), where the max (RnL, GnL, BnL) represents a maximum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL,
• the additive-color-mixture matrix being defined in accordance with specification of the image to be displayed, a product of the additive-color-mixture matrix and a three-rows-one-column matrix composed of the signals (RnL, GnL, BnL) resulting in a three-rows-one-column matrix composed of tristimulus values,
• the purity coefficient ‘Ψ’ having a value that varies to approach a value ‘TH1’ with an increase in a value of the coefficient ‘Purity’ and varies to approach a value ‘1’ with a decrease in the value of the coefficient ‘Purity’, the value ‘TH1’ representing a ratio given by an expression of WR+G+B—max/(WR+G+B—max+WW—max), where the parameter ‘WR+G+B—max’ represents designed maximum white luminance that is realized with the red sub-pixel, the green sub-pixel, and the blue sub-pixel in a pixel of the pixels, and the parameter ‘WW—max’ represents designed maximum white luminance that is realized with the white sub-pixel in the pixel of the pixels,
• the first matrix being configured of a difference obtained through subtracting first tristimulus values from second tristimulus values, the first tristimulus values being a product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL) when all of the values of the signals (RnL, GnL, BnL) are min (RnL, GnL, BnL), and the second tristimulus values being obtained through multiplying the purity coefficient ‘Ψ’ by the product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL), and
• the second matrix being an inverse matrix of a matrix obtained through multiplying the additive-color-mixture matrix by ‘TH1’.

A signal generation method generating a red sub-pixel signal, a green sub-pixel signal, a blue sub-pixel signal, and a white sub-pixel signal, based on a red-display image signal, a green-display image signal, and a blue-display image signal that are provided in accordance with an image to be displayed,

• the signal generation method comprising:
• determining values of the red sub-pixel signal Rcvt, the green sub-pixel signal Gcvt, and the blue sub-pixel signal Bcvt, based on a first matrix and a second matrix, with use of a coefficient ‘Purity’, an additive-color-mixture matrix, and a purity coefficient ‘Ψ’;
• and
• employing a value of the white sub-pixel signal Wcvt as a value of min (RnL, GnL, BnL), where the min (RnL, GnL, BnL) represents a minimum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL that are linearized and normalized and are provided for each of the pixels,
• the coefficient ‘Purity’ being defined by a value obtained through subtracting the min (RnL, GnL, BnL) from max (RnL, GnL, BnL), where the max (RnL, GnL, BnL) represents a maximum value of the red-display image signal RnL, the green-display image signal GnL, and the blue-display image signal BnL,
• the additive-color-mixture matrix being defined in accordance with specification of the image to be displayed, a product of the additive-color-mixture matrix and a three-rows-one-column matrix composed of the signals (RnL, GnL, BnL) resulting in a three-rows-one-column matrix composed of tristimulus values,
• the purity coefficient ‘Ψ’ having a value that varies to approach a value ‘TH1’ with an increase in a value of the coefficient ‘Purity’ and varies to approach a value ‘1’ with a decrease in the value of the coefficient ‘Purity’, the value ‘TH1’ representing a ratio given by an expression of WR+G+B—max/(WR+G+B—max+WW—max), where the parameter ‘WR+G+B—max’ represents designed maximum white luminance that is realized with the red sub-pixel, the green sub-pixel, and the blue sub-pixel in a pixel of the pixels, and the parameter ‘WW—max’ represents designed maximum white luminance that is realized with the white sub-pixel in the pixel of the pixels,
• the first matrix being configured of a difference obtained through subtracting first tristimulus values from second tristimulus values, the first tristimulus values being a product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL) when all of the values of the signals (RnL, GnL, BnL) are min (RnL, GnL, BnL), and the second tristimulus values being obtained through multiplying the purity coefficient ‘Ψ’ by the product of the additive-color-mixture matrix and the matrix of the signals (RnL, GnL, BnL), and
• the second matrix being an inverse matrix of a matrix obtained through multiplying the additive-color-mixture matrix by ‘TH1’.