An image processing apparatus comprises a storage unit configured to store image data read by scanning, with a linear sensor including pixels arranged in a main-scanning direction, an original in a sub-scanning direction orthogonal to the main-scanning direction, an acquisition unit configured to acquire inclination information indicating inclination of the image data; and a readout unit configured to read out the image data from the storage unit, with shifting, in accordance with the inclination information, a line position in the sub-scanning direction by each predetermined number of pixels in the main-scanning direction, wherein the readout unit reads out the image data from the storage unit, based on the inclination information, differentiating the predetermined number of pixels between an edge in the main-scanning direction and other parts.

An object of the present invention is to detect the home position with a high accuracy without being affected by temperature. The present invention is an image reading apparatus having a reading portion, and the apparatus includes: an acquisition unit configured to acquire first data obtained by the reading portion reading a main scanning line in a state where a light source of the reading portion is turned on in a first light quantity, and second data obtained by the reading portion reading the main scanning line in a state where the light source of the reading portion is turned on in a second light quantity smaller than the first light quantity; a generation unit configured to generate difference data by subtracting the value of the second data from the value of the first data; and a determination unit configured to determine whether a mark arranged at a position corresponding to a home position of the reading portion has been detected on the main scanning line based on the difference data.

A read sensor generates front side image information indicating an image on a front side of an object to be read, and front side measurement information indicating a line of an image in a main scanning direction on the front side of a correction chart. A read sensor generates back side image information indicating an image on a back side of the object to be read, and back side measurement information indicating a line of an image in the main scanning direction on the back side of the correction chart. The image correction device calculates an amount of misalignment of read positions based on the front side measurement information and the back side measurement information, and corrects misalignment of images on the front side and the back side of the object to be read, indicated by the front side image information and the back side image information.

An image reading apparatus includes a front-side reader, which includes a white LED configured to irradiate an original with light and a CMOS sensor configured to receive light that is reflected by the original. The front-side reader is configured to generate read data that represents a luminance value of an image on the original from the result of receiving light with the CMOS sensor. The image reading apparatus stores, in a non-volatile memory, a condition for determining whether there is a sub-scanning color shift, and uses a sub-scanning color shift detector to determine whether there is a sub-scanning color shift based on the read data obtained from the front-side reader and the condition stored in the non-volatile memory. When there is a sub-scanning color shift, the image reading apparatus corrects the sub-scanning color shift by correcting the read data with a color shift corrector.

An image processing device includes a modulation clock generator, a line synchronization signal generator, a line image sensor, and an image processor. The modulation clock generator is configured to generate the modulation clock by modulating a frequency of a reference clock at a predetermined modulation cycle. The line synchronization signal generator is configured to generate, on the basis of the modulation clock, a line synchronization signal whose line cycle varies from line to line. The line image sensor is configured to sequentially read an image of one line of a document at a timing corresponding to the line synchronization signal and to output image data. The image processor is configured to process the image data on the basis of the modulation clock.

An image processing device includes: a compression unit that compresses original image data in units of a block; a first position correction unit that shifts positions of respective pixels contained in the original image data compressed by the compression unit such that the positions are shifted in a sub scanning direction; an expansion unit that expands the original image data shifted by the first position correction unit; and a second position correction unit that converts resolution of the original image data into higher resolution, and shifts the positions of the respective pixels of the converted original image data, wherein the first shift amount is a shift amount set in units of a shift corresponding to an integral multiple of the block, and the second shift amount is a shift amount set in units of a shift corresponding to one pixel with high resolution converted by the second position correction unit.

An image forming apparatus including: a drive motor configured to rotate a rotary polygon mirror to deflect light beam; a signal generation unit configured to generate a rotation synchronous signal; and a rotation control unit configured to control a rotation speed of the rotary polygon mirror, wherein the rotation control unit executes a disabling processing of disabling control of the drive motor based on the rotation synchronous signal, wherein a term of a first disabling processing for a first rotation speed is shorter than a term of a second disabling processing for the second rotation speed, and wherein when the rotation speed of the rotary polygon mirror is changed from the first rotation speed to the second rotation speed, the rotation control unit switches the disabling processing from the first disabling processing to the second disabling processing after reduction of the rotation speed of the rotary polygon mirror is started.

A scanner include a scan section configured to intermittently move and perform an intermittent scan, a stop-state analyzing section configured to compare a stop-time image obtained by a scan of an identification pattern on a medium in a stop position where the movement of the scan section temporarily stops and scan results before and after the stop and determine, based on a comparison result, whether the medium moved, and a scan control section configured to cause the scan section to suspend the temporarily-stopped intermittent scan when the medium moved and cause the scan section to continue the temporarily-stopped intermittent scan when the medium did not move.

In an image processing system, an image reading apparatus determines whether an error occurs on a read image that is an image read by an image sensor, and generates and transmits data including the read image and error information that is information indicating presence or absence of occurrence of the error, and an image processing apparatus receives the data and performs, on the read image, image processing corresponding to the presence or absence of occurrence of the error, based on the error information.

An outer peripheral member disposed at an outer periphery of a platen glass includes first and second reference surfaces. The first reference surface is a lower surface of an area extending along a side edge portion of the platen glass at an end in a main scanning direction. The second reference surface is located adjacent to the first reference surface in a second direction and differs in light reflectance from the first reference surface. An image processing portion determines whether outer periphery pixel data of an outer periphery area in line image data acquired successively while a scanning unit is moving, satisfies a border condition. A unit driving portion positions the scanning unit to a home position by moving the scanning unit a predetermined distance from where the scanning unit is located when it is determined that the outer periphery pixel data satisfies the border condition, and stops it.