Abstract: An improvement to an image processing system for enhancing the contrast of digital images using a local-area contrast enhancement of the digital images. For each digital image, a contrast factor is computed which is a measure of how well exposed the digital image is based on a normalized intensity value for each of the image pixels. A gain value for each of the image pixels is determined, and scaled by the contrast factor. A surround image based on a filtered version of the digital image is formed and using in conjunction with the scaled gain values to perform opponent contrast filtering to the digital image to produce an output image.

Abstract: An improvement to an image processing system for enhancing the contrast of digital images using a local-area contrast enhancement of the digital images. For each digital image, a contrast factor is computed which is a measure of how well exposed the digital image is based on a normalized intensity value for each of the image pixels. A gain value for each of the image pixels is determined, and scaled by the contrast factor. A surround image based on a filtered version of the digital image is formed and using in conjunction with the scaled gain values to perform opponent contrast filtering to the digital image to produce an output image.