Ricoh Company, Ltd.

Makio Kondo

Hajime Tsukahara

Hayashi Taniguchi

Yoshiaki Ozeki

A correction-data generating unit divides, into a matrix of row blocks in a sub scanning direction and column blocks in a main scanning direction, white data on a transfer drum read by a reading unit during a predetermined time period that is shorter than a time period in which the read point of the transfer drum is returned to a position where the reading unit has started reading the first white reference member, calculates, for each column of the matrix, a correction-data candidate value corresponding to a variation ratio of a mean of data of the row blocks in the sub-scanning direction, and determines a minimum value of the calculated correction-data candidate values as the correction data. A shading-data correcting corrects the shading data by using the generated correction data. A shading correcting unit performs shading correction on image data of a document after the correction data is generated.

Image reading apparatus, image forming apparatus, and shading correction method

An encoding/decoding method for carrying out conversion between run lengths and corresponding run length codes is provided. The run length codes has a format including a first part for storing first information and a second part for storing second information. The first information indicates the length of the code and the second information indicates the corresponding run length. The total number of bits of each of the run length codes is set as an integral multiple of a predetermined number of bits. The present encoding/decoding method is suitable for use in an image processing system, such as a facsimile machine.

Growing community of inventors

Kanagawa, Japan

Makio Kondo