IMAGE OUTLINE ENHANCING CIRCUIT, PARTICULARLY CONCERNED WITH AMPLIFYING A CERTAIN FREQUENCY BAND TO BE ENHANCED AMONG INPUT IMAGE SIGNALS ACCORDING TO LEVELS OF THE IMAGE SIGNALS AND PROPERLY PROCESSING THE IMAGE SIGNALS

摘要

PURPOSE: An image outline enhancing circuit is provided to amplify a certain frequency band to be enhanced among input image signals according to levels of the input image signals, and to properly process the amplified image signals, thereby enhancing image outlines at more than a certain level. CONSTITUTION: A level controller(30) detects levels of image signals having a certain frequency band to compare the levels with a reference level, generates a control signal to maintain outline enhancement levels of image signals whose levels are less than the reference level, and maintains outline enhancement levels of image signals whose levels are more than the reference level at more than a certain level by controlling amplifying gains. A selective input unit(10) selectively inputs image signals having the same frequency band as the image signals detected from the level controller(30) among plural frequency bands. A selective output unit(40) amplifies and processes the image signals inputted through the input unit(10) as many as the amplifying gains, and selectively outputs either maximum values or minimum values of original image signals delayed for a certain time and the image signals whose outlines are enhanced.