Patent ID: 7161626

Claim:
An image reading apparatus, comprising: photoelectrically converting means for photoelectrically converting image information obtained from optically reading an original image, line by line, and outputting an image signal, said photoelectrically converting means having optically shielding means provided at a portion thereof; and black shading correcting means for correcting the image signal using a black reference level, said black reference level being obtained from said portion of said photoelectrically converting means for each line during an operation of the reading of the original image, wherein the black reference level used by said black shading correcting means for each line is obtained using black reference values, each of the black reference values being data of said portion of said photoelectrically converting means for a respective one of a plurality of lines, wherein the black reference level is a moving average of averages of the black reference values for the plurality of lines, wherein each black reference value for a respective line is an average of pixel values in a main scan direction, the moving average being obtained from moving-averaging, in a sub-scan direction, the black reference values.