A method, and document scanner system, for correcting image values recorded by an optical document scanner with multiple color cameras arranged in a staggered configuration with overlap scan areas includes storing color correction values mapped to respective color index values, where a color correction value is computed from a color difference between a first color value and a second color value of the respective overlap sets, and correcting a third color value which is a color value from the second set of color image values by a color correction value which is looked up via a color index value determined from the third color value. Thereby color variations among staggered cameras are corrected.

According to an embodiment of the present invention, to improve processing performance, a printing apparatus that performs printing by using a printhead formed by a plurality of headchips includes one CPU, a table configured to store processing contents set by the CPU, and a plurality of processing units configured to process, in parallel, printing data to be used in each headchip by commonly using the table and in accordance with the processing contents set in the table. In addition, the apparatus includes a plurality of control units configured to wait for the completion of the processing of each processing unit, synchronize the plurality of processing units for next processing, and cause each of the processing units to execute the next processing in accordance with the processing contents set in the table.

An estimated image data calculator is configured to calculate, as estimated image data, for each of image data of respective colors outputted from an imaging element, on the basis of a pixel value of a first pixel on one of two lines adjacent to each other in the image data, and a pixel value of a second pixel on the other of the two lines and adjacent to the first pixel, image data of a non-reading region between a reading region in a document corresponding to the one of the two lines and a reading region in the document corresponding to the other of the two lines. A pixel value correcting unit is configured to correct at least one of the pixel value of the first pixel and the pixel value of the second pixel on the basis of the estimated image data.

A method, and document scanner system, for correcting image values recorded by an optical document scanner with multiple color cameras arranged in a staggered configuration with overlap scan areas includes storing color correction values mapped to respective color index values, where a color correction value is computed from a color difference between a first color value and a second color value of the respective overlap sets, and correcting a third color value which is a color value from the second set of color image values by a color correction value which is looked up via a color index value determined from the third color value. Thereby color variations among staggered cameras are corrected.

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.