A FILTER FOR ADAPTIVELY EXTRACTING A LOCAL ILLUMINATION

摘要

A filter (1) for retracting an local adaptation luminance component (IL) from an image signal (IS) comprising samples of an image composed of pixels (Pi j). The filter (1) comprises a footprint (FP) covering a group of neighboring pixels (Pi j). An edge detector (12) detects edges in an image part of the image within the footprint (FP). An accumulator (16) accumulates sample values of a set of neighboring pixels (Pi j) within the footprint (FP) to obtain a sum (A), the set comprising a central pixel (P22) positioned centrally in the footprint (FP) and pixels (Pi j) not being separated from the central pixel (P22) by an edge in the image. A normalizer (15, 17) normalizes the sum (A) with respect to a number of pixels in the set (B).