Abstract: An image processing apparatus includes circuitry that acquires a colorimetric value for each of a plurality of patches on a first chart printed out by an image forming apparatus and read by a colorimeter. Each of the patches has a monochromatic color. The circuitry further acquires a maximum tone value previously set in accordance with a sheet, and converts each of the colorimetric value, the maximum tone value, and a color system value of a first target into a particular color value. The first target represents an ideal characteristic of the color system value corresponding to a tone value. The circuitry further determines, as a second target, a characteristic passing through a point determined by a color value corresponding to the maximum tone value. The characteristic is generated based on the color system value of the first target converted into the particular color value.

Abstract: An image processing device includes: a first contamination detection circuit to detect contamination on an image reading device using a first relative threshold value calculated from a standard deviation of pixel values of a same-density region in a read image obtained by the image reading device, the image reading device reading a reference image formed on a recording medium by a line head including a plurality of inkjet heads and that has density regions of a plurality of gradations; a second contamination detection circuit to detect contamination on the image reading device using a second relative threshold value calculated from a standard deviation of pixel values of an area in the read image, the area being divided for each of the plurality of inkjet heads; and a contamination processing circuit to eliminate an influence of the contamination on the read image when at least one of the first contamination detection circuit or the second contamination detection circuit determines the contamination.

Abstract: An image processing apparatus includes control circuitry. The control circuitry is configured to: acquire first image data to be subjected to color conversion; and convert the first image data acquired, into second image data in which a dot area ratio of a target process color of process colors indicated by the first image data is distributed into a distributed dot area ratio of a fluorescent color different from the target process color and a distributed dot area ratio of the target process color.

Abstract: An image processing apparatus includes circuitry that acquires a colorimetric value for each of a plurality of patches on a first chart printed out by an image forming apparatus and read by a colorimeter. Each of the patches has a monochromatic color. The circuitry further acquires a maximum tone value previously set in accordance with a sheet, and converts each of the colorimetric value, the maximum tone value, and a color system value of a first target into a particular color value. The first target represents an ideal characteristic of the color system value corresponding to a tone value. The circuitry further determines, as a second target, a characteristic passing through a point determined by a color value corresponding to the maximum tone value. The characteristic is generated based on the color system value of the first target converted into the particular color value.

Abstract: An image processing apparatus includes control circuitry. The control circuitry is configured to: acquire first image data to be subjected to color conversion; and convert the first image data acquired, into second image data in which a dot area ratio of a target process color of process colors indicated by the first image data is distributed into a distributed dot area ratio of a fluorescent color different from the target process color and a distributed dot area ratio of the target process color.