Abstract
Digital photography systems often render an image from a scene-referred description with very wide dynamic range to an output-referred description of much lesser dynamic range. Global tone maps are often used for this purpose, but can fail when called upon to perform a large amount of range compression. A luminance formulation of the Retinex ratio-reset-product-average algorithm produces a smoothly changing contrast mask of great benefit, but it too can fail where high contrast edges are encountered. A slight but critical modification to the Retinex equation - introducing a ratio modification operator - changes the nature of the generated contrast mask so that it is simultaneously smooth in regions of small contrast ratios, but extremely sharp at high contrast edges. A mask produced in this way compresses large and undesirable contrast ratios while preserving, or optionally enhancing, small ratios critical to the sensation of image contrast. Processed images may appear to have a greater contrast despite having a shorter global contrast range. Adjusting the new operator prior to processing gives control of the degree of compression at high contrast edges. Changing the operator during processing gives control over spatial frequency response.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.