Gray scale correction circuit

Abstract

Abstract This invention relates to a gray level correction circuit for effective use of the cathode ray tube with a small dynamic range, and has as its object to make a gray level correction on the video signal which has passed the contrast circuit and on the video signal with any value of contrast without making the picture whitish. A gray level correction circuit comprising: a cumulative histogram circuit (1) for forming a cumulative histogram for each field of the input video signal, and outputting a result; a first multiplier circuit (2) for multiplying output of the cumulative histogram circuit (1) by a first constant; a normalizing circuit (3) for normalizing output of the first multiplier circuit (2) by diving by the total number of samples, and outputting a normalized signal; an interpolation circuit (4) for outputting a correction value for each pixel by using output of the normalizing circuit (3) and the input video signal; a second multiplier circuit (5) for multiplying output of the interpolation circuit (4) by a second constant; and an adder circuit (6) for adding output of the second multiplier circuit (5) to the input video signal.

Inventors

• 👤 Naoji Okumara
• 👤 Yosuke Izawa

Bibliographic Details