An image processing device includes: a first gradation-process determining unit that determines a type of gradation process for a process-color toner plate in accordance with halftone mode information; a second gradation-process determining unit that determines a type of gradation process for a special toner plate other than a process color in accordance with the type of gradation process determined by the first gradation-process determining unit; and a halftone processing unit that performs halftone processes in accordance with the types of gradation processes that are determined by the first gradation-process determining unit and the second gradation-process determining unit.

An electrophotographic image forming apparatus, which utilizes a line head in which a plurality of light-emitting elements is arranged as a light source, includes at least one controller having at least one processor and at least one memory. The controller is configured to obtain print data to perform printing, perform halftone processing for the obtained print data, generate a plurality of pieces of correction information for correcting variations of light amount on a photosensitive body by light radiated from the plurality of light-emitting elements, and correct the print data for which the halftone processing has been performed by using the correction information. The correction information includes various profiles for correcting the variations of light amount.

A computational halftoning process determines a halftoned image having halftoned pixel values by processing an array of input pixels. For each input pixel, an array of high-resolution printer coordinates is defined at a higher spatial resolution than the printer resolution, and a coordinate transformation is applied to determine a corresponding array of high-resolution dot coordinates. An array of high-resolution halftoned pixel values is then determined responsive to the code value of the input pixel by addressing a halftone dot function using the array of high-resolution dot coordinates. A halftoned pixel value is then determined by averaging the high-resolution halftoned pixel values.

Provided is a control unit that executes a first mode in which a developer bearing member rotates with respect to an image bearing member at a first circumferential speed ratio, and a second mode in which the developer bearing member rotates with respect to the image bearing member at a second circumferential speed ratio greater than the first circumferential speed ratio. In the second mode, in a case where information indicating that output image data includes acquiring only a first pattern of first gradation, the control unit controls to apply a first transfer voltage, and, in a case where information indicating acquiring output image data that includes the first pattern and a second pattern of second gradation with lower density than the first gradation, the control unit controls to apply a second transfer voltage having an absolute value less than the first transfer voltage.

An image forming system includes plural photoreceptors with surfaces on which electrostatic latent images attributable to a difference in charging potential are formed, plural development devices that are provided to face the photoreceptors, that respectively accommodate toners of different colors, and that develop the electrostatic latent images by means of the toners, plural developer accommodation portions that accommodate developers of different colors each of which contains a toner of a normal color, which is any one of yellow, magenta, cyan, or black, or a toner of a special color other than the normal color and a carrier, plural supply paths through which the developers from the developer accommodation portions are respectively supplied to the development devices, and at least one processor configured to execute a discharge mode in which, in a case where a cleaning developer accommodation portion accommodating a cleaning developer that is a replacement and that contains a toner of a new color and a larger number of carriers than a usual number of carriers is attached to a supply path, the cleaning developer is supplied so that a developer before replacement that is in the supply path and a development device is discharged, and a switch mode in which the developer in the supply path and the development device is switched with the cleaning developer.

An exposure head includes a substrate on which light sources are mounted, and a condensing optical system. A memory stores a profile indicating correction gains for exposure amounts. A sensor detects a temperature. A processor acquires a correction gain that corresponds to a position of a light source that reached an exposure timing, corrects, for each of the light sources, an exposure amount of the light source with the correction gain corresponding to the position of the light source, and adjusts, for each of the light sources, a reference position of the corresponding correction gain in the profile in accordance with the temperature detected by the sensor.