An apparatus prints images for a density adjustment on a plurality of sheets, reads the image on a sheet printed later among the plurality of printed sheets, determines a representative value by carrying out a calculation from at least a first density value read from an image at a predetermined position on a first sheet and a second density value read from an image at the predetermined position on a second sheet, which are printed later, and performs a print density adjustment using the determined representative density and a target density.

A grayscale adjustment method of a display panel, a grayscale adjustment device and a display device using the same are provided. The grayscale adjustment method includes steps of capturing an image of the display panel to obtain a current image; identifying a non-uniform block in the current image, and detecting an original output brightness value and an original input grayscale of the non-uniform block; determining a target input grayscale corresponding to a preset target brightness value according to an actual gamma curve value, wherein the actual gamma curve value is obtained by testing the display panel; and setting a difference between the original input grayscale and the target input grayscale as a grayscale compensation value of the non-uniform block.

There are provided a printing system, a method of generating a halftone processing rule, a method of acquiring a characteristic parameter, image processing device and method, a halftone processing rule, a halftone image, a method of manufacturing a printed material, an ink jet printing system, and a program which are capable of reducing an operation load of a user and acquiring a halftone processing rule appropriate for the printing system. A characteristic parameter acquisition chart including a pattern for acquiring characteristic parameters related to characteristics of the printing system is output, and the output characteristic parameter acquisition chart is read by image reading means. The characteristic parameters are acquired by analyzing the read image of the characteristic parameter acquisition chart, and halftone processing rules that define the processing contents of halftone processes used in the printing system are generated based on the acquired characteristic parameters.

On a recording sheet of a first size, an image combined with gradation patches of a plurality of colors is printed, on a recording sheet of a second size smaller than the first size, images combined with the gradation patches of the plurality of colors are divided and printed into a plurality of recording sheets, color measurement is performed on each of the gradation patches, and gradation correction data is generated.

The present disclosure provides processing for performing highly-accurate density nonuniformity correction while saving the number of patches. A chart generation unit obtains measurement data of the latest test chart. A patch tone calculation unit obtains an output characteristic expressing measurement values for input tone values based on the obtained measurement data and calculates selected tone values to be used as the input tone values for a test chart from the obtained output characteristic. A chart image generation unit generates the test chart by using the calculated selected tone values as the input tone values and not using at least one initial tone value as the input tone value.

A method of printing improved printed products using defect-free printing machine nozzles and compensated defective nozzles includes printing products and a test chart with test fields onto a transported substrate, the test fields having tonal values, every test field including an unprinted line from a nonactivated, nonprinting nozzle compensated by a neighboring nozzle having a compensation value, pairs of tonal value and compensation value being specified and used for the chart, recording an image of the chart, computer-analyzing the image and determining the compensation value. Every pair of tonal value and compensation value is used multiple times in the chart and a corresponding number of spaced apart test fields is created. A characteristic value representing test field homogeneity and determining compensation value quality is assigned to every measuring field. The best characteristic value regarding a specified criterion and the compensation value is determined for every tonal value.

An image processing apparatus obtains a plurality of measured values obtained by measuring a measurement image; and replaces a first measured value with a value based on a second measured value. The first measured value being included in the plurality of measured values and being unsuitable for identifying the density characteristic, and the second measured value being included in the plurality of measured values and being suitable for identifying the density characteristic.

An example operation method of an image forming apparatus includes forming a test image with respect to a pattern used for diagnosing an image-quality state of a printout output by the image forming apparatus, obtaining a test signal corresponding to the test image via a sensor of the image forming apparatus, obtaining image-quality state information indicating an image-quality state of the test image based on the test signal corresponding, identifying a type of a screen corresponding to halftone information indicating a resolution of the printout based on the image-quality state information, and performing a first image forming operation according to the type of the screen.

A method of printing improved printed products using defect-free printing machine nozzles and compensated defective nozzles includes printing products and a test chart with test fields onto a transported substrate, the test fields having tonal values, every test field including an unprinted line from a nonactivated, nonprinting nozzle compensated by a neighboring nozzle having a compensation value, pairs of tonal value and compensation value being specified and used for the chart, recording an image of the chart, computer-analyzing the image and determining the compensation value. Every pair of tonal value and compensation value is used multiple times in the chart and a corresponding number of spaced apart test fields is created. A characteristic value representing test field homogeneity and determining compensation value quality is assigned to every measuring field. The best characteristic value regarding a specified criterion and the compensation value is determined for every tonal value.

An image forming apparatus comprises an image forming unit; a sensor that measures a measurement image; and a controller. The controller controls the image forming condition based on a measurement result of measuring a first measurement image; acquires information having a correlation to density variation of images to be formed by the image forming unit; controls the image forming condition based on the information; determines a first value regarding a density of an image to be formed, based on a measurement result of measuring a second measurement image; determines a second value regarding a density of the image to be formed by the image forming unit, based on the information; and controls a timing at which the image forming unit next forms the first measurement image, based on the first value and the second value.