Abstract: A panel drive circuit having an input interface to which an image signal is input, a gamma correction circuit that corrects an image processing signal generated by an image processing circuit performing image processing on the image signal input to the input interface, such that a gamma correction signal thus generated has predetermined gamma characteristics, an unevenness correction circuit that corrects the gamma correction signal generated through the correction by the gamma correction circuit, based on correction data for reducing unevenness of a display panel, and an D/A convertor that has a variable output voltage range, and performs D/A conversion on an unevenness correction signal generated through the correction by the unevenness correction circuit and outputs the signal thus generated to the display panel, and the unevenness correction circuit changes the correction method according to the output voltage range of the D/A convertor.

Abstract: An unevenness correction data generation device suppressing the appearance of color unevenness when turning on R, G and B together includes a pattern generation unit causing red, green and blue images, in which display panel subpixels are turned on at the same gray level, to be displayed, a monochrome camera, a control unit generating first red, green and blue luminance correction data based on shooting data of the monochrome camera, a pattern generation unit causing the display panel to display a white image by causing red, green and blue images corrected with the respective luminance correction data to be displayed simultaneously, a color camera shooting the white image in color, and a control unit generating color correction data for correcting color unevenness based on shooting data of the color camera and generates unevenness correction data based on the red, green and blue luminance correction data and the color correction data.

Abstract: An image processing device includes: a calculator that calculates a gray scale histogram for each color component of an image signal; a calculator that calculates, for each color component, a maximum and a minimum of classes having a frequency greater than zero in the gray scale histogram; a determiner that generates, for each color component, a histogram having classes each having an absolute difference value between the frequencies of adjacent classes in the gray scale histogram, and compares the absolute difference values in the histograms with a value to determine, from the presence or absence of an absolute difference value exceeding the value, an image type of the image; a generator that generates a gray scale correction curve from the calculated maximum and minimum for each color component; and a corrector that performs gray scale correction on the image signal using the gray scale correction curve.

Abstract: An image processing device includes: a calculator that calculates a gray scale histogram for each color component of an image signal; a calculator that calculates, for each color component, a maximum and a minimum of classes having a frequency greater than zero in the gray scale histogram; a determiner that generates, for each color component, a histogram having classes each having an absolute difference value between the frequencies of adjacent classes in the gray scale histogram, and compares the absolute difference values in the histograms with a value to determine, from the presence or absence of an absolute difference value exceeding the value, an image type of the image; a generator that generates a gray scale correction curve from the calculated maximum and minimum for each color component; and a corrector that performs gray scale correction on the image signal using the gray scale correction curve.

Abstract: An ink sheet damage calculating unit compares image element density data of each of areas into which an image is divided by an image area dividing unit with a first threshold to calculate the total number of pixels each having density data equal to or larger than the first threshold for each area, and then compares the total number of pixels calculated for each area with a second threshold. A printing operation selecting unit uses a remaining area of an already-used ink area for formation of a next print image when the total number of pixels is smaller than the second threshold in every one of all the areas, and uses an ink area in a new unit area for formation of a next print image when the total number of pixels is equal to or larger than the second threshold.

Abstract: An ink sheet damage calculating unit compares image element density data of each of areas into which an image is divided by an image area dividing unit with a first threshold to calculate the total number of pixels each having density data equal to or larger than the first threshold for each area, and then compares the total number of pixels calculated for each area with a second threshold. A printing operation selecting unit uses a remaining area of an already-used ink area for formation of a next print image when the total number of pixels is smaller than the second threshold in every one of all the areas, and uses an ink area in a new unit area for formation of a next print image when the total number of pixels is equal to or larger than the second threshold.

Abstract: The present invention provides a method of controlling a thermal head which is capable of maintaining high image sharpness even in high-speed printing. In the method of controlling a thermal head according to the present invention, resistors constituting the thermal head is energized and non-energized, thereby realizing an image with a predetermined gradation. Further, one line period includes one energizing period in which energization is performed and one non-energizing period in which non-energization is performed, and the resistors are energized during the energizing period after the non-energizing period in the one line period.

Abstract: An accumulated-heat correction apparatus for a thermal head, wherein print data of each line are outputted to the thermal head, and a conduction time of the thermal head is controlled on the basis of the print data, includes cumulative-data calculation means for calculating cumulative data which is ascribable to accumulated heat of the thermal head up to a previous line (n?1), next-line data calculation means for calculating print data of a next line (n+1), correction-data generation means for calculating correction data (?Ts) which corrects print data of a current line n, by using the cumulative data and the next-line data, and head control means for controlling the conduction time of the thermal head on the basis of the correction data (?Ts) which has been generated by the correction-data generation means.

Abstract: The present invention provides a method of controlling a thermal head which is capable of maintaining high image sharpness even in high-speed printing. In the method of controlling a thermal head according to the present invention, resistors constituting the thermal head is energized and non-energized, thereby realizing an image with a predetermined gradation. Further, one line period includes one energizing period in which energization is performed and one non-energizing period in which non-energization is performed, and the resistors are energized during the energizing period after the non-energizing period in the one line period.

Abstract: An accumulated-heat correction apparatus for a thermal head, wherein print data of each line are outputted to the thermal head, and a conduction time of the thermal head is controlled on the basis of the print data, includes cumulative-data calculation means for calculating cumulative data which is ascribable to accumulated heat of the thermal head up to a previous line (n?1), next-line data calculation means for calculating print data of a next line (n+1), correction-data generation means for calculating correction data (?Ts) which corrects print data of a current line n, by using the cumulative data and the next-line data, and head control means for controlling the conduction time of the thermal head on the basis of the correction data (?Ts) which has been generated by the correction-data generation means.