| 摘要 |
PROBLEM TO BE SOLVED: To obtain a favorable image by eliminating influence due to variations in illumination depth characteristics of a contact image sensor. SOLUTION: An image reading device reads an image having a uniform density chart by the contact image sensor device 100, and stores a read picture signal output from the contact image sensor device 100 to an image memory 34. A target value TA is set from the read picture signal of a central portion in a main scanning direction out of the read picture signal stored in the image memory 34. An operation of an operation expression (I):α(i)=TA/PX(i) (PX(i) is a value of the read picture signal for adjustment at i-th main scanning position.) for the read picture signal at each main scanning position of the read picture signal stored in the image memory 34 is performed to obtain a correction coefficientα(i) (i is the main scanning position) for correcting variations in illumination depth in the main scanning direction. Characteristics are deteriorated at a constant ratio due to the illumination depth regardless of thickness of the manuscript. Variations in output level of the read picture signal can be corrected by multiplying the read picture signal of each main scanning position obtained in reading a document by the correction coefficientα(i). COPYRIGHT: (C)2011,JPO&INPIT |
