A processor causes a printing portion to execute, when first conveying processing is executed, test print processing for executing processing of forming a plurality of test toner images on a sheet under a print condition that differs for each of the plurality of test toner images. The processor acquires a plurality of first sensing densities when the first conveying processing is executed. The processor causes the printing portion to execute the test print processing when second conveying processing is executed. The processor acquires a plurality of second sensing densities when the second conveying processing is executed. The processor compares the plurality of first sensing densities and the plurality of second sensing densities to adjust the print condition in the print processing when the second conveying processing is executed.

A downtime relating to formation and detection of a detection image is reduced. An image forming apparatus includes a controller configured to calculate a first conversion unit to convert a gradation of input image data so that density output for the input image data becomes a first density output characteristic based on a first detection result of the detection image detected by a density sensor in a first mode. The controller generates a second conversion unit to convert the gradation of the input image data so that the density output for the input image data becomes a second density output characteristic in the second mode based on the detection result in the first mode and correction information, and further updates the correction information based on a second detection result of the detection image detected by the density sensor in the second mode and the first detection result.

An image forming apparatus includes an image processing unit configured to perform image processing corresponding to an image forming mode on image data; a controller configured to control the image processing unit to perform the image processing corresponding to the image forming mode on measurement image data, control an image forming unit to form the measurement image based on the measurement image data, to control a measurement unit to measure the measurement image, and to control an image forming condition based on a measurement result. In a case where the measurement image is formed while the image forming apparatus consecutively forms a plurality of images in the second image forming mode, the controller controls the image forming unit to form the measurement image without performing the image processing corresponding to the second image forming mode.

An image forming apparatus is capable of switching thresholds for deciding a color registration amount from a pattern image. A controller controls image forming units to form first and second color patterns of different colors on a rotational image bearing member. The second color pattern is formed at an upstream side of the first color pattern in a rotational direction of the image bearing member. The controller controls a sensor to detect the color patterns. A comparator compares a detection result by the sensor with a threshold, and outputs an output value according to a comparison result. The controller controls the color registration according to the output value. The controller sets a second threshold for the second color pattern based on an edge timing of the output value from the comparator according to the comparison result between the detection result about the first color pattern and a first threshold.

With reference to a correction value revision parameter table, a periodic non-uniformity correction value corresponding to changed rotational speed is obtained from the correction value revision parameter table, and set as a new periodic non-uniformity correction value corresponding to the rotational speed of a rotary component, and thereby a gradation which is an image formation parameter of image data is corrected.

An image forming apparatus includes a developing device that performs a developing process by using two-component developer; an image carrier that carries a toner image including a toner band developed by the developing device; a density detection unit that detects a density of the toner band; and a determining unit that determines whether or not to perform a density adjustment on the basis of the density of the toner band detected by the density detection unit.

An image forming device is provided. The image forming device may include a transfer belt to move in a preset direction, a plurality of image generators to respectively generate a toner image on the transfer belt, and a controller to output an image generation signal to each of the plurality of image generators such that the plurality of image generators respectively generate a toner image. A plurality of toner images generated using the plurality of image generators are arranged on the transfer belt in parallel to each other, and an arrangement order of the plurality of toner images is identical to an arrangement order of the plurality of image generators.

An image forming system includes: a density detecting section that detects the density of a toner image formed on an image bearing member by an image forming section, the density being detected as an output image density; a hardware processor which performs; tone correction in accordance with input-output characteristics data indicating the relationship between an input image density and an output image density, the input image density being the image density of a tone component included in the input image data, the output image density being detected by the density detecting section in accordance with the tone component; determining whether there is a missing tone component in the input image data; and complementing the input-output characteristics data corresponding to a missing tone component, when it is determined that there is the missing tone component.

An image forming apparatus includes a latent image bearer to bear a plurality of halftone images having a same image density and a high-density image located one cycle downstream of the latent image bearer from at least one of the plurality of halftone images, a transferor to apply a predetermined transfer voltage to transfer the plurality of halftone images and the high-density image, a transfer electric field forming target to bear the plurality of halftone images and the high-density image transferred from the latent image bearer, a detector to detect image densities of the plurality of halftone images on the transfer electric field forming target, and a controller to determine a primary transfer voltage applied at a time of image formation, based on image density variations of the plurality of halftone images detected by the detector.

Provided is an image forming apparatus, which is configured to form measurement images for detecting color misregistration exhibited in a main scanning direction on an intermediate transfer belt in the order of: a measurement image of a reference color, a measurement image of a second color, a measurement image of the reference color, a measurement image of a third color, a measurement image of the reference color, a measurement image of a fourth color, and a measurement image of the reference color in a sub-scanning direction. The image forming apparatus is also configured to detect the measurement images for detecting color misregistration over an entire area of the intermediate transfer belt in the main scanning direction by a line sensor unit, and to correct color misregistration exhibited in the main scanning direction based on detection results.