Local contrast enhancement of IR images
Jerry Silverman · 1992
Low contrast details in wide-dynamic-range IR imagery may well be lost in global, monotonic map- pings from raw signal levels to 8-bit displays. Local contrast enhancement techniques can bring out such detail through mappings which are no longer global or monotonic. Three groups of algorithms for this purpose are described and compared with regard to degree of enhancement, artifacts, and computa- tional costs. The groups are: local implementations of histogram projection; "modulo" processing, which is a triangular-shaped many-to-one mapping; and high frequency enhancement as implemented in the spatial domain but designed in the spatial frequency domain. Results are illustrated by a representa- tive subset of the numerous IR images surveyed.