Patent ID: 7120294

Claim:
An image forming apparatus which reads a color image on an original and subjects a signal of the read color image to image processing, thus forming a color image, the apparatus comprising: an image reading section which reads a color image on an original; a first memory section which stores basic filter coefficients and decimal-point reference position information for subjecting a color image signal of the color image read by the image reading section to image processing; a second memory section which has a predetermined bit width and stores filter coefficients; a calculation section which re-calculates, when a degree of sharpness has been adjusted in the image processing, the basic filter coefficients stored in the first memory section in accordance with a value of the adjustment; a computing section which calculates a bit number between a lowest bit and a highest bit, which are obtained by expressing in binary form a coefficient with a maximum absolute value of the filter coefficients calculated by the calculation section; a first processing section which effects a bit shift of the filter coefficients calculated by the calculation section and stores the bit-shifted filter coefficients in the second memory section, on the basis of the bit number calculated by the computing section and the bit width of the second memory section; an altering section which alters the decimal-point reference position information on the basis of the decimal-point reference position information stored in the first memory section and the bit width of the second memory section; an arithmetic section which subjects the filter coefficients stored in the second memory section and the color image signal of the color image read by the image reading section to a matrix arithmetic operation in the processing of the first processing section; and a second processing section which effects a bit shift of the image signal produced by the arithmetic section, on the basis of the decimal-point reference position information altered by the altering section.