Patent ID: 7085427

Claim:
A computer system, comprising: a memory configured to temporarily store an output value as a filter processing result; a first calculator configured to calculate a difference between an input value of an image signal and the output value stored in said memory, the output value being the filter processing result of a previous input value; a lookup table configured to respectively store a plurality of differences and corresponding change values, and to output a change value corresponding to the difference calculated by said first calculator, the change value being a product of the difference and a value which is above “0” and below “1” if an absolute value of the difference is below a threshold, and the change value being a product of the difference and a value which is above “−1” and below “0” if the absolute value is above the threshold; and, a second calculator configured to output a difference between the input value and the change value and to store the difference being newly stored in said memory.