A method for calibrating a printing process by applying a selected adjustment curve to an image input file to produce an output file. The adjustment curve is derived to match a target tonal response curve having a function value for 0 that is non-zero or has a discontinuity between 0 and 10%. The adjustment curve has a basic part selected from limited options and an intersecting highlight part derived using a 1-dimensional function having input parameters selected from limited options. The adjustment curve has a starting point (X1, Y1), a highlight curve part having a first slope at the starting point and a first intersection with the basic curve part at (X2, Y2). The first slope and first intersection are among the input parameters selected from limited options. The basic curve part has a second slope at a midrange point (X3>X2, Y3>Y2).

An image forming apparatus includes a conversion unit configured to convert image data based on a conversion condition, an image forming unit configured to form an image on a sheet based on the converted image data, a detection unit configured to detect a pattern image on a transfer member, a reading unit configured to read a test image formed on a sheet, a controller configured to perform calibration based on a reading result of the reading unit, and a reception unit. In a case where the calibration is performed, the controller determines an image forming condition based on a result of detection by the detection unit before the test image is formed. In a case where the reception unit receives the discontinuation instruction, the controller changes the image forming condition to an image forming condition before the pattern image is formed.

An image forming apparatus includes a forming unit, a generation unit, a storage unit, a correction unit, and a changing unit. The forming unit forms an image. The generation unit generates correction data for correcting density unevenness for each of a plurality of regions divided in a main scanning direction of an image formed by the forming unit. The storage unit stores the correction data generated by the generation unit. The correction unit corrects a density of an image to be formed by the forming unit for each of the plurality of regions based on the correction data stored by the storage unit. The changing unit changes an image formation density by the forming unit with a uniform amount of change for the plurality of regions after the correction data is generated by the generation unit.

An image forming apparatus includes a forming unit, a generation unit, a storage unit, a correction unit, and a changing unit. The forming unit forms an image. The generation unit generates correction data for correcting density unevenness for each of a plurality of regions divided in a main scanning direction of an image formed by the forming unit. The storage unit stores the correction data generated by the generation unit. The correction unit corrects a density of an image to be formed by the forming unit for each of the plurality of regions based on the correction data stored by the storage unit. The changing unit changes an image formation density by the forming unit with a uniform amount of change for the plurality of regions after the correction data is generated by the generation unit.

Disclosed is a method for converting image data. The method includes: acquiring image data of a target image, wherein the image data includes first pixel values of m pixels in the target image, each of the first pixel values includes a first color value of at least one color channel, the first color value being within a target color value interval of the at least one color channel; dividing the target color value interval into n color value partitions; determining a color value partition where the first color value falls from the n color value partitions; and converting the first color value into a second color value according to a position of the first color value in the color value partition, the number of bits occupied by the second color value being less than the number of bits occupied by the first color value.

A method for preparing digital image data from an analog image input by scanning, and reducing visibility of the scanning noise, may include estimating a visibility of scanning noise, and a number of scanning samples needed to reduce scanning noise to below a visible threshold. Related methods include scanning, by an analog-to-digital image scanner, an analog image for multiple iterations, resulting in digital image data for each of the iterations; calculating a noise statistic for individual pixels of digital image data across the iterations; determining true values of individual pixels of the digital image data based on the noise statistic for each of the individual pixels and generating scanner noise reduced digital image data wherein pixels are assigned their respective ones of the true values; and saving the scanner noise reduced digital image data in a computer memory.

A method for brightness and color correction of image data of a line camera is disclosed, wherein, for the detecting of image data with at least two line arrays of the line camera while illuminating a detection area of the line camera with an illumination module, a gray-scale image and at least two single-color images are recorded, and the image data is corrected with the help of a brightness function of the illumination module which is dependent on a line position of the line array and/or a distance of recorded objects. The brightness function is determined for the illumination module in advance and independent of the line camera and is stored in the illumination module, and the brightness function is read out by the line camera and used for the respective correction of the gray-scale image and the single-color images.

An image sensor and an image processing system in which the image sensor includes a sensing unit configured to generate a plurality of images having different luminances with respect to a same object, a pre-processor configured to merge n images (n is a natural number equal to or greater than 2) except for at least one of the plurality of images to generate a merged image, and an interface circuit configured to output the at least one image and the merged image to an external processor.

An image forming apparatus includes an image forming portion, a first acquisition processing portion, a second acquisition processing portion, and an adjustment processing portion. The image forming portion forms an image on a sheet. The first acquisition processing portion acquires a captured image of the sheet. The second acquisition processing portion acquires a specific value that indicates a difference between a gradation value of a pixel that, among pixels included in the captured image acquired by the first acquisition processing portion, corresponds to a higher part of an outer surface of the sheet, and a gradation value of a pixel that, among the pixels included in the captured image, corresponds to a lower part that is lower than the higher part. The adjustment processing portion adjusts an image forming condition of the image forming portion based on the specific value acquired by the second acquisition processing portion.

An image forming apparatus includes: a setting unit configured to set an operation mode; and a processing unit configured to perform image processing on image data according to the operation mode. In a case where a first mode is set, the image processing includes determining, in the image data, one or more target pixels having a gradation value equal to or higher than a first threshold value, and one or more adjacent pixels that are different from the one or more target pixels and adjacent to the one or more target pixels, setting a first gradation value lower than the first threshold value as a gradation value of the one or more target pixels, and setting a second gradation value higher than the first gradation value as a gradation value of the one or more adjacent pixels.