What is disclosed is an apparatus and method for calibrating an optical module of a document scanning device. In one embodiment, imaging sensors of an optical module of the scanning device are used to obtain an image scan of a calibration strip mounted on a surface of a platen on which a sheet to be scanned has been manually placed. The calibration strip has a first vertical line at a first distance from a right edge of the strip, a second vertical line at a second distance from a left edge of the strip, and a sloping horizontal line positioned between the first and second vertical lines. A slope of the horizontal line is non-zero. In a manner more fully disclosed herein, the image scan of the calibration strip is to obtain calibration measurements. The calibration measurements are, in turn, used to calibrate the scan head of the optical module.

A method of measuring a display delay includes a first step where a first display device performs a switching operation of switching a display pattern displayed on a display unit of the first display device, a second step where a first camera captures a first image and displays the first image in a live view mode, a third step where a second camera captures a second image containing the first image and records at least the first image contained in the captured second image while being correlated with information indicative of an imaging time when the second image is captured, and a fourth step where a display delay time of the first camera from the imaging of the first image to the display of the first image is deduced from the time indicated by the display pattern contained in the first image and the information indicative of the imaging time.

An image processing apparatus includes an acquisition unit that acquires, from image data acquired in such a manner that a chart formed by an image forming unit is read, a line signal value from pixel values of pixels for a line arranged in a first direction of the chart and a line representative value by using line signal values respectively acquired from a plurality of lines adjacent to each other in a second direction different from the first direction of the chart, and a determination unit that determines a portion where a streak is generated in the second direction by using a difference between a first representative value and a second representative value.

A method of measuring a shutter time lag of a camera includes: a first step of switching a display pattern of a display unit including i (i is a natural number greater than 2) display elements to a different display pattern at every time TP, and in the first step, the number of j (j is a natural number, and 1<j<i) display elements to be brought into a first display state among i display elements is switched at every time TP; a second step of capturing an image of the display unit in response to a shutter operation of the camera performed in synchronization with the switching operation; and a third step of deducing a shutter time lag taken from the shutter operation to the imaging of the display unit from the image captured by the camera.

Provided is an image reading device including an irradiation section that irradiates a reading position with light, a color chart that includes plural color patches, and that is provided on a curved surface of a rotatable roller, an image capturing section that captures an image of the color chart at the reading position, and that outputs image signals which express the captured image, a correction section that corrects the image signals using a correction coefficient corresponding to the curved surface, and a calibration section that performs calibration using the image signals, which are corrected by the correction section, and representative color values of the plural color patches, the representative color values being stored in advance.

An image reading apparatus includes: a conveyance roller; a plurality of line image sensors; a first obtainment means that obtains coordinates of a plurality of dot patterns on the basis of read data obtained by reading a chart printed a first dot column and a second dot column; a second obtainment means that obtains a distance between coordinates of adjacent dot patterns; and a third obtainment means that obtains a correction value for reading of an image. The chart, the dot patterns of the first dot column and the dot patterns of the second dot column are arranged to be offset from each other in the conveyance direction, and the third obtainment means obtains the correction value on the basis of a conveyance direction distance between coordinates of dot patterns in the first dot column and a conveyance direction distance between coordinates of dot patterns in the second dot column.

An image forming system includes: an image scanning portion that scans an image formed on a paper; and a processor that controls image forming based on a scanned image obtained through scanning of the image scanning portion, in which the processor is configured to: define, in an intermediate state in which a reference point of a mark for positional deviation detection is not included in an analysis region set with respect to the scanned image and a part of the mark is included in the analysis region, a temporary position in place of an actual position of the reference point based on the part of the mark; and correct an image forming position on the paper based on the temporary position.

A printing device includes a recording head, a main scanning unit, a conveyance unit, and a control unit. The conveyance unit includes an upstream drive roller including a first gear, a downstream drive roller including a second gear, and a rotary element meshing with the first gear and the second gear. The control unit performs control for ejecting droplets to a cantilevered print area from the recording head moving along a main scanning direction in a state where a phase of the rotary element is a first phase and thus forming a first test pattern, and ejecting droplets to the cantilevered print area from the recording head moving along the main scanning direction in a state where the phase of the rotary element is one or more second phases shifted from the first phase by k(n/m) cycles and thus forming a second test pattern.