The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 22, 1992
Filed:
Dec. 26, 1990
Jon A Fairhurst, Grass Valley, CA (US);
The Grass Valley Group, Inc., Nevada City, CA (US);
Abstract
A chrominance filtering system reduces chrominance detail when sufficient luminance detail is present, but limits how much chrominance detail is reduced when insufficient luminance detail is present. The chrominance input signal is applied to a high pass filter and a suitable delay circuit. The output of the high pass filter, C.sub.hp, is a signal indicative of chrominance detail. It is applied to the input of a bipolar clipping circuit that also receives a control signal, .vertline.Y.sub.hp '.vertline..sub.clipped indicative of luminance detail. The control signal is derived by high pass filtering, rectifying and low pass filtering the luminance signal to produce a signal, .vertline.Y.sub.hp .vertline., that is absolute value of high pass filtered luminance activity. This signal is then scaled by multiplication by a first constant and then offset by addition to a second constant to produce .vertline.Y.sub.hp '.vertline.. .vertline.Y.sub.hp '.vertline. is then clipped to be between a minimum and a maximum value to produce the control signal .vertline.Y.sub.hp '.vertline..sub.clipped. The bipolar clipping circuit constrains C.sub.hp to produce C.sub.hpc according to the following relationships: If C.sub.hp is > or =0, then C.sub.hpc is > or = to .vertline.Y.sub.hp '.vertline..sub.clipped ; or if C.sub.hp is <0, then C.sub.hpc is < or = to -.vertline.Y.sub.hp '.vertline..sub.clipped. The first and second constants and the minimum and maximum values are optimized empirically.