Method for variable contrast mapping of digital images
OwnerRobert E. Sobol, John J. McCanninventors
Life of this patent
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Abstract
A method of local contrast mapping that changes the dynamic range of an original image to more closely match the dynamic range of the medium used for the reproduction. The method variably compresses large contrast differences between different areas of an image while variably modifing small contrast differences between different areas of an image.
Claims41
A method of changing the dynamic range of an original image to more closely match the dynamic range of the medium used for a reproduction, comprising:
- modifying the contrast differences between different areas of the original image as a function of the distance between the different areas.
A method of changing the dynamic range of an original image to more closely match the dynamic range of the medium used for a reproduction, comprising:
- modifying the small contrast differences between different areas of the original image as a function of the distance between the different areas;
- limiting the maximum contrast differences between different areas of the original image, where the limit is a function of the distance between the different areas.
A method of changing the dynamic range of an original image to more closely match the dynamic range of the medium used for a reproduction, comprising:
- modifying the small contrast differences between different areas of the original image as a function of the distance between the different areas;
- limiting the maximum contrast differences between different areas of the original image.
A method of changing the dynamic range of an original image to more closely match the dynamic range of the medium used for a reproduction, comprising:
- preserving small contrast differences between different areas of the original image;
- limiting the maximum contrast differences between different areas of the original image, where the limit is a function of the distance between the different areas.
A method of improving an apparatus that sequentially determines a comparative measure of the radiance information for providing a new intermediate value of each such measure in response to the product of a ratio function of the radiance information associated with each of a first named segmental area and with each of a second named segmental area and of a like measure previously determined for the second named segmental area, and determining a sequentially new value of each said measure in response to a selectively weighted averaging of the new intermediate value and a like measure previously determined for the first named segmental area, comprising:
- modifying the small contrast differences of the ratio function as a function of the distance between the first named segmental area and the second named segmental area;
- limiting the maximum contrast differences of the ratio function, where the limit is a function of the distance between the first named segmental area and the second named segmental area.
A method of improving an apparatus that sequentially determines a comparative measure of the radiance information for providing a new intermediate value of each such measure in response to the product of a ratio function of the radiance information associated with each of a first named segmental area and with each of a second named segmental area and of a like measure previously determined for the second named segmental area, and determining a sequentially new value of each said measure in response to a selectively weighted averaging of the new intermediate value and a like measure previously determined for the first named segmental area, comprising:
- modifying the small contrast differences of the ratio function as a function of the distance between the first named segmental area and the second named segmental area;
- limiting the maximum contrast differences of the ratio function.
Dependencies are inferred from the claim text.