Forward look ahead techniques for tracking background and noise levels in scanned video images

摘要

Apparatus, and an accompanying method, for use in an image enhancement system for providing background and noise values which, in many instances, are more representative of background and noise levels occurring in a scanned video image than those values previously obtainable in the art. This apparatus, which in its general form can be used to implement both a noise tracking circuit and/or a background tracking circuit, includes a two-dimensional non-linear, preferably infinite impulse response, filter that provides an output filtered value based upon the value of an incoming pixel situated on a current scan line and to first and second prior output values. The first prior output value is the output filtered value that is associated with a pixel located on a pre-determined one of a plurality of prior scan lines and situated to the right of the current pixel. The second prior output value is the output filtered value that is associated with a pre-selected pixel situated on the current scan line and located to the left of said current pixel.