An image reading device that efficiently performs shading correction that flexibly responds to changes in the diffusion properties of reflected light on the surface of a reading target efficiently performing same as a result of including: controlling a plurality of light sources so as to cause only a specific light source among the light sources to be lit; obtaining the diffusion state of a first reflected light generated by the specific light source being lit, in a state in which general shading correction data not dependent on the image reading target is generated; obtaining a diffusion state for a second reflected light generated by light being irradiated on to the reading target by the specific light source; and generating dedicated shading correction data that relies on the reading target, based on the first reflected light diffusion state, the second reflected light diffusion state, and the general shading correction data.

An image reading device includes a background unit, a reading unit, and circuitry. The background unit is configured to be a background in reading of a recording medium and includes a first region that is black and a second region that is different from the first region. The reading unit is configured to read an image with the background unit as the background, and generate a read value based on a result of reading the image with the background unit. The circuitry is configured to correct the read value based on a reference value generated by the reading unit by reading the second region of the background unit.

An image reading apparatus includes: a reader that reads an image on a print medium, and is arranged at a reading position of a conveyance path for conveying the print medium that is continuous and has a long length; a shading unit including a reference color member to perform shading correction of correcting a read value of an image sensor in the reader; a mover that moves the shading unit between the reading position of the reader and a retreated position; and a retractor that retracts the print medium from the reading position of the reader, wherein the retractor arranges the print medium at the reading position of the reader at a time of reading by the reader, and retracts the print medium from the reading position of the reader at an end of reading by the reader, to secure a predetermined space between the reader and the print medium.

An image forming apparatus includes a printer, a first reader, a second reader, and a processor. The printer is configured to print an image having diagnostic information on a sheet of paper. The first reader is configured to read a first image from the sheet of paper. The second reader is configured to read a second image from the sheet of paper. The processor is configured to cause a display to display a diagnosis result of a defect based on the first image and the second image.

A color measurement apparatus comprising: a color measurement unit configured to perform color measurement of an image on a sheet, the color measurement unit including a light source; a reference member used for calibration of the color measurement unit; a moving unit configured to move the color measurement unit to a first position at which the light source irradiates a region other than the reference member with light and a second position at which the light source irradiates the reference member with light; and a control unit configured to, after causing the light source to emit light when the color measurement unit is positioned at the first position, and then moving the color measurement unit to the second position, execute the calibration based on data obtained by causing the light source to irradiate the reference member with light.

An image reading apparatus includes a stacking unit, a conveyance unit to convey stacked sheets, a reading unit, a white reference plate provided in a second position, and a processor. The reading unit is movable and, at a first position, reads a conveyed sheet image to obtain image data and, at the second position, reads the white reference plate. The processor generates, based on a plate reading result, a shading correction value and corrects the image data using the shading correction value. Based on whether the number of times in which reading the white reference plate has been performed is less than a predetermined number of times, the reading unit changes a time interval in a reading period that is from a first timing to a second timing. The processor generates, each time the white reference plate is read, the shading correction value based on the plate reading results.

An image reading device includes: an FB glass; a sensor module having a light source and a plurality of sensors; and an image processor that generates correction data to be used for shading correction and performs the shading correction on image signals by using the correction data. The plurality of sensors is arranged in a main scanning direction and is configured to form an image signal on a single line. The image processor acquires second black data by causing the plurality of sensors to acquire an image signal of a reference sheet placed on the FB glass with the light source turned on, and generates black correction data based on the second black data. By performing the shading correction by using the black correction data, the image processor corrects density unevenness, in an image, caused by interference between image signals from the plurality of sensors.

An image reading apparatus according to an embodiment of the present invention includes: an image sensor to read a document; a movement unit configured to relatively move the document and the image sensor by using a motor as a drive source; an output unit configured to output data of a plurality of colors based on accumulated light-receiving signals by accumulating the light-receiving signals from the image sensor for each color in order for each line in a direction of the movement based on an encoder pulse output from an encoder in accordance with rotation of the motor; and a correction unit configured to perform shading correction for each piece of data of the plurality of colors output by the output unit by using a correction value to correct influence on data of the plurality of colors due to a dark current in the image sensor based on shading data.

An image reading apparatus includes a stacking unit, a conveyance unit to convey stacked sheets, a reading unit, a white reference plate provided in a second position, and a processor. The reading unit is movable and, at a first position, reads a conveyed sheet image to obtain image data and, at the second position, reads the white reference plate. The processor generates, based on a plate reading result, a shading correction value and corrects the image data using the shading correction value. Based on whether the number of times in which reading the white reference plate has been performed is less than a predetermined number of times, the reading unit changes a time interval in a reading period that is from a first timing to a second timing. The processor generates, each time the white reference plate is read, the shading correction value based on the plate reading results.

A colorimetric device and a colorimetric method according to the present invention extract a chart region candidate, which is a candidate for a chart region, from an image of a color chart, obtain an evaluation value of this chart region candidate, determine whether or not the chart region candidate is the chart region based on this obtained evaluation value, obtain each position of a plurality of patches for the chart region candidate determined as the chart region as a result of the determination and colorimetrically measure each of the patches at each obtained position of the plurality of the patches.