The embodiments herein relate to a method performed by a system (100) for handling variations in a mark (110) printed by a group (105) of industrial printers (101). The system (100) obtains images of the printed mark (110) printed by each of the printers (101) in the group (105). The system (100) creates a composite image from the obtained images. The printed marks (110) appear as a repeating pattern in the composite image. The system (100) compares the printed marks (110) in the composite image to each other or to another mark. The system (100) detects variations with a first resolution in the printed marks (110) in the composite image as a result of the comparison. The system (100) creates an augmented image in which the detected variations are augmented to a second resolution. The first resolution is lower than the second resolution.

In an image reading device, a controller is configured to perform: calculating a ratio between first and second reference data as evaluation data; designating a target light receiving element from a plurality of light receiving elements one by one sequentially; calculating average evaluation data of the target light receiving element by averaging the evaluation data of a second number of light receiving elements located at positions apart every predetermined distance equal to a length of a first number of consecutively arranged light receiving elements; setting an evaluation range of the target light receiving element by adding/subtracting a predetermined value to/from the average evaluation data; determining whether the evaluation data falls within the evaluation range; in response to determining that the evaluation data is out of the evaluation range, revising the second reference data of the target light receiving element; and generating correction data using the second reference data after revision.

Embodiments of the present disclosure provide an image calibration method, an image forming apparatus, and a storage medium. The method includes outputting a calibration image in response to a calibration instruction, where the calibration image includes a calibration pattern and a calibration mark; according to the calibration mark of the calibration image, determining whether a calibration event corresponding to the calibration image matches a calibration event corresponding to a current calibration operation, or determining whether a calibration event type corresponding to the calibration image matches a calibration event type corresponding to a current calibration operation; and performing image calibration according to the calibration pattern in the calibration image if the calibration event corresponding to the calibration image matches the calibration event corresponding to the current calibration operation, or if the calibration event type corresponding to the calibration image matches the calibration event type corresponding to the current calibration operation.

A method for testing the reliability of an error detection of an image inspection method by using a computer includes producing a defective test image by superposing specific error elements on an error-free reference image, carrying out the image inspection method with the defective test image, comparing the errors found by the image inspection method with the error set to be expected with the aid of the known errors added to the test image, and evaluating the reliability of the image inspection method with the aid of the difference between found and expected errors.

A lighting device (23) irradiates a web under conveyance with light. The lighting device includes a light source (43), and an irradiation port (61) configured to open linearly in a widthwise direction of the web at an end portion facing the web. The irradiation port (61) is formed between first and second parallel portions (62b, 63b) where a first plate member (62) and a second plate member (63) parallelly face each other. The web under conveyance is irradiated with linear light. It is possible to provide a lighting device capable of irradiating only an inspection region of a sheet or a web with light.

A chart includes a plurality of area images. Each area image of the plurality of area images includes a figure. The figure indicates positional information of each area image of the plurality of area images in the chart. An image forming apparatus includes an image forming device configured to form an image on a sheet to create the chart, and an image reading device configured to read the image in the chart.

A first surface of a first sheet has a second image formed in advance. An image forming system generates reference data based on a result of reading an image on the first surface of the first sheet on which a first image is not formed, generates first image data that represents a result of reading an image on the first surface of the first sheet having the first image formed on the first surface, and determines, based on the reference data and the first image data, a relative position between the first image and the second image on the first surface of the first sheet.

An image evaluation device includes: a reading unit that reads a sample image included in a sample printout recognized as a non-defective printout and that reads an inspection object image included in an inspection object printout obtained by printing an image corresponding to the sample image on a recording medium using a printing device based on image data representing the image; an extraction unit that extracts a line defect including a linear pattern formed in a specific direction from the inspection object image represented by inspection object image data, based on a difference value between sample image data obtained by reading the sample image and the inspection object image data; and an evaluation unit that evaluates a visibility of the line defect extracted by the extraction unit.

An image forming apparatus includes: an image forming unit configured to form an image on a sheet; a conveyance unit configured to convey the sheet having the image formed thereon to a conveyance path; a reading unit configured to read a test image of a sheet conveyed to the conveyance path; and a controller configured to: determine an adjustment value for adjusting a geometric characteristic of an image to be formed by the image forming unit based on a reading result of the reading unit; control the image forming unit to form the test image; control the reading unit to read the sheet having the test image formed thereon; determine an adjustment value for adjusting a geometric characteristic of an image to be formed by the image forming unit based on a reading result of the reading unit.

A method for reducing image burn-in artifacts in an electrophotographic printing system, includes receiving a print job including image data for a set of pages to be printed. The pages are analyzed to determine that the image data for a sequence of pages in the print job are similar. The similar pages are printed using a pattern of lateral translations wherein the image data is laterally translated such that it is printed at a different lateral position on the printed page.