Image filter processing apparatus and method

摘要

A memory stores an output value as a filter processing result. A first calculator calculates a difference between an input value of an image signal and the output value stored in the memory. The output value is the filter processing result of a previous input value. A lookup table stores a plurality of difference values and change values, and outputs the change value corresponding to the difference calculated by the first calculator. The change value is 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 is a product of the difference and a value which is above "-1" and below "0" if the absolute value is above the threshold. A second calculator outputs a difference between the input value and the change value.