Provided is an image forming system including a first image forming device, a second image forming device; and an image reading device. A first hardware processor of the first image forming device causes a first image former of the first image forming device to form a first reference image on a first face of a sheet. A second hardware processor of the second image forming device causes a second image former of the second image forming device to form a second reference image different from the first reference image on the first face of the sheet. A third hardware processor of the image reading device determines whether an image positional deviation is present based on the first reference image and the second reference image that are formed on the first face of the sheet and that are read by the image reading device.

An image forming apparatus includes an image former configured to form a first image on a first recording medium; a feeder configured to feed the first recording medium to the image former; a reader configured to read the first image formed on the first recording medium; a process executor configured to execute a predetermined process based on a first read image that is obtained by the reader by reading the first image; and a corrector configured to correct the reader based on a second read image that is obtained by the reader by reading a second image formed on a second recording medium fed by the feeder, and a predetermined read reference image.

Certain examples relate to a method of color matching by confirming a color-rendering device. Color reproduction parameters are determined for a reference and target color-rendering device. A color matching parameter is determined for the target color-rendering device based on a comparison of the color reproduction parameter for the target color-rendering device with the corresponding color reproduction parameter of the reference color-rendering device. The color-rendering device is confirmed dependent on the color matching parameter. Color resources of the target color-rendering device are configured such that a rendering of a color image on the target color-rendering device replicates a rendering of the color image on the reference color-rendering device.

Provided is an image forming system including a first image forming device, a second image forming device; and an image reading device. A first hardware processor of the first image forming device causes a first image former of the first image forming device to form a first reference image on a first face of a sheet. A second hardware processor of the second image forming device causes a second image former of the second image forming device to form a second reference image different from the first reference image on the first face of the sheet. A third hardware processor of the image reading device determines whether an image positional deviation is present based on the first reference image and the second reference image that are formed on the first face of the sheet and that are read by the image reading device.

A color accuracy verification device includes: a hardware processor that: acquires a colorimetric value for each color patch of color accuracy verification charts generated by a plurality of printers; stores the colorimetric value in time series; sets a target printer to carry out color accuracy verification; and verifies color accuracy based on: the colorimetric value of the target printer stored in the hardware processor; and a verification reference value set in advance; and a display that displays a verification result by the hardware processor for the target printer.

In an example, a print target may be printed with a calibration target. The calibration target may comprise an first printing fluid figure printed on the print target and a second printing fluid figure printed on the print target. A geometric figure may be defined by the second printing fluid figure. The geometric figure may be negatively outlined in the second printing fluid figure. In an example, the calibration target may be processed to define a geometric relationship between an first printing fluid reference point and a second printing fluid reference point.

A display unit color-correction method includes: a first step of displaying a prescribed image on a display unit of a portable communication terminal that includes an imaging unit and the display unit; a second step of acquiring imaging data by imaging a color chart, which is a printed matter, and the display unit with the prescribed image displayed thereon together or individually by the imaging unit; and a third step of correcting a color of the display unit by using color information on the prescribed image in the imaging data and color information on a color in the color chart in the imaging data.

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.

An image forming apparatus includes an image forming device configured to form an image on a sheet using a rotating body under a predetermined image forming condition, a corrector configured to determine a correction amount for the image forming condition to adjust image density unevenness corresponding to a rotation cycle of the rotating body, and a controller configured to control the image forming device to form, on a single sheet, plural test images that are different in the correction amount.

In response to reception of instructions to print a color sample from a user, first, a printing unit is caused to perform calibration. Then, after the calibration is completed in the printing unit, control is performed so that print data is generated by execution of predetermined image processing for image data representing the color sample and printing processing of the print data is performed in the printing unit.