Image content based improvements to locally adaptive video enhancement

Three classes of adaptations to systems for video processing are presented. These three techniques are special purpose modifications to commonly used algorithms. The first technique limits excursions of peak white and black with minimum compromise of edge enhancement. The second is a method of preserving perceived chroma when processing luminance. The third is an adaptive contrast term to control the enhancement level in black regions of an image such that noise often associated with dark scene material is not enhanced. All three techniques have been installed on various real-time image processors made by DigiVision for specialty tasks such as night vision and medical endoscopy