Patent ID: 6956975
Filing Date: 2005-10-18
Classification: G06T

Abstract:
1. A method of enhancing high contrast details of an input image for rendering it effectively on an output display medium comprising the steps of: constructing a tone scale curve from the input image; applying the tone scale curve to the input image to produce a tone-scaled image; applying a decomposition filter bank to the tone-scaled image to produce the low-pass tone-scaled image; applying the decomposition filter bank to the input image to produce the high-passed input image in each spatial scale; generating the contrast weight control signals from the high-passed input image in each spatial scale; adjusting the high-passed input image in each scale according to said contrast weight control signals; and applying a reconstruction filter bank to the low-pass tone-scaled image and the adjusted high-pass input image to produce a contrast enhancement presentation image for rendering on an output display medium, said step of generating the contrast weight control signals including the steps of: applying a decomposition filter bank to the input image to produce a high-passed input image at a coarse scale; computing a gradient amplitude of the high-passed input image at the coarse scale; creating a mapping function wherein an output value T is large when the gradient amplitude at the coarse scale is moderate and the output value T is small when the gradient amplitude at the coarse scale is very small and very large; and using the output value T as a mask image.