Digital filter for executing a video emphasis process through mode selection.

摘要

A digital filter having a characteristic expressed by a rational function executes a signal processing in a predetermined sequence in accordance with a pre-emphasis mode or de-emphasis mode. A first digital filter (23) has a characteristic expressed by a denominator polynomial of the rational function and processes an input signal according to this characteristic to produce a first process signal. A second digital filter (25) has a characteristic expressed by a numerator polynomial of the rational function and processes an input signal according to this characteristic to produce a second process signal. A mode selector (30) selects one of the pre-emphasis and de-emphasis modes. A first switch (22) supplies the input signal to the first digital filter (23) in accordance with the pre-emphasis mode and supplies the second process signal from the second digital filter (25) to the first digital filter (23) in accordance with the de-emphasis mode. A second switch (24) supplies the first process signal from the first digital filter (23) to the second digital filter (25) in accordance with the pre-emphasis mode and supplies the input signal to the second digital filter (25) in accordance with the de-emphasis mode.