An image forming apparatus comprises: an image processor to convert image data based on a conversion condition; an image forming unit to form an image based on the converted image data using a replaceable member; a memory to store the image data and the converted image data; a sensor to perform measurement on a test image; and a controller. If the replacement of the replaceable member is detected while forming images, the controller controls the image forming unit to form the test image and generates the conversion condition based on a result of the measurement on the test image. If the replacement of the replaceable member is detected while forming the images, the controller further controls the image processor to convert the image data stored in the memory based on the generated conversion condition.

In some examples, a supply component for a printing device includes a memory device comprising a plurality of corrective data to produce a corresponding plurality of color tables each customized for a respective media type of a plurality of media types, wherein a respective corrective data of the plurality of corrective data corresponds to nodes of a reference color table for the printing device that is able to accept the plurality of media types for printing. The respective corrective data includes a plurality of residual values to transform the nodes of the reference color table to a customized color table for use with a selected media type of the plurality of media types.

An image processing apparatus is configured to: acquire a correction factor from a recording unit for recording, for each of a plurality of pixels, the correction factor for correcting a difference in pixel value corresponding to a difference between a spectral sensitivity and a preset reference spectral sensitivity in a predetermined wavelength range at a pixel of interest, based on image data generated by an image sensor, the image sensor having the plurality of pixels on which color filters of a plurality of colors with different spectral transmittances are respectively located, the color filters forming a predetermined array pattern; calculate a correction amount for correcting a pixel value of the pixel of interest based on the correction factor at the pixel of interest and pixel values of pixels surrounding the pixel of interest; and correct the pixel value of the pixel of interest by using the correction amount.

In some examples, a print cartridge includes a memory device comprising quantized coefficients derived from a compression of a difference table including a plurality of difference nodes in which each difference node represents a value that is a difference of a value of a node of a color table and a value of a corresponding node of a reference table, the quantized coefficients useable to produce a reconstructed difference table, and a plurality of residue nodes in which each residue node represents a value that is a difference of a value of a node of the color table and a value of a corresponding node of the reconstructed difference table.

A print system includes an image processing apparatus and a print apparatus that receives a print job processed by the image processing apparatus and prints an image on a sheet. The print apparatus determines whether or not a print job received from the image processing apparatus is a measurement target for measuring an image printed on a sheet, measures the image on the sheet printed by executing a print job that has been determined to be the measurement target, and transmits the result of measurement to the image processing apparatus. The image processing apparatus generates a print job serving as a measurement target, and upon receiving the result of measurement based on the transmitted print job, applies the result of measurement to a print job to be printed by the print apparatus.

Certain examples described herein relate to the control of colorants and treatments for printing. In certain examples image data, a colorant color mapping and one or more treatment color mappings is obtained. The colorant color mapping may be used to map the image data to colorant application values. The one or more treatment color mappings may be used to map the image data to treatment application values. The colorant application values and treatment application values may be used to generate discrete print control instructions to apply the set of colorants and set of treatments to a printing substrate.

A method of adapting a Lab setpoint color value of multicolored printed products, wherein a special color is replaced by process colors using an ICC color profile. A measurement point that is assigned to the replaced special color on the printed product is metrologically acquired using a color measuring system and a Lab actual color value of the measurement point is calculated. The ICC color profile or a standardized ICC color profile is used for computing the color composition of the Lab setpoint color value from the participating process colors. Changes of the layer thicknesses of the participating process colors are ascertained to achieve a predetermined Lab setpoint color value of the measurement point using a digital tool or a digital model. The participating process colors are adapted using the ascertained changes of their layer thicknesses.

A color expression conversion apparatus includes a color expression conversion rule storage unit that stores a rule for converting a textual expression of a specific color into another textual expression, and a color expression conversion control unit that converts a textual expression of a color included in document data into another textual expression in accordance with the rule.

A transform wrapper is stored on a memory device and the memory device may be included in a printer cartridge. The transform wrapper may dynamically build a transform map for a printer based on metadata stored at the memory device. The metadata may indicate at least one of a type of depositing material, transform map, print media and printer.

Described are methods and devices for applying a color gamut mapping process on a first image to generate a second image, where the content of the first and second images is similar but the respective color spaces of the first and second images are different. The color gamut mapping process may be controlled using a color gamut mapping mode obtained from a bitstream where the color gamut mapping mode belongs to a set comprising at least two preset modes and an explicit parameters mode. If the obtained color gamut mapping mode is the explicit parameters mode and the color gamut mapping process is not enabled for the explicit parameters mode, the color gamut mapping process may be controlled by a substitute color gamut mapping mode determined from additional data.