Vector-based color difference metric for color mapping

A color mapping module which performs image color mapping of an original image represented as an array of a plurality of pixels, the color mapping module comprising:

• a transforming module constructed to transform the original image using a color mapping algorithm to generate a color mapped image;
• and
• a correction module constructed to:
• identify pixels in smooth areas in the original image by applying an edge-detection algorithm that detects pixels in edge areas and pixels in smooth areas of the original image;
• generate a color difference map between the color mapped image and the original image, wherein the color difference map is comprised of color difference vectors for each of the plurality of pixels of the original image, wherein the color difference vector for each pixel includes both a magnitude and a directionality representing a difference for color data in each pixel in the original image, relative to color data in a corresponding mapped pixel in the color mapped image;
• identify pixels in the color difference map having large color differences in color movement relative to nearby pixels in the color difference map, by applying an edge-detection algorithm to the color difference map to identify edge areas of the color difference map for which pixels in the color difference map have large differences of color movement relative to nearby pixels, and smooth areas of the color difference map for which pixels do not have large differences of color movement relative to nearby pixels;
• and
• apply, for each pixel that is identified in a smooth area in the original image and is identified as having a large color difference in the color difference map, a correction algorithm, so as to provide a corrected color mapped image.

A color mapping apparatus comprising:

• a computer-readable memory constructed to store computer-executable process steps;
• and
• a processor constructed to execute the computer-executable process steps stored in the memory;
• wherein the process steps stored in the memory cause the processor to perform image color mapping of an original image represented as an array of a plurality of pixels, and include computer-executable process steps to:
• transform the original image using a color mapping algorithm to generate a color mapped image;
• identify pixels in smooth areas in the original image by applying an edge-detection algorithm that detects pixels in edge areas and pixels in smooth areas of the original image;
• generate a color difference map between the color mapped image and the original image, wherein the color difference map is comprised of color difference vectors for each of the plurality of pixels of the original image, wherein the color difference vector for each pixel includes both a magnitude and a directionality representing a difference for color data in each pixel in the original image, relative to color data in a corresponding mapped pixel in the color mapped image;
• identify pixels in the color difference map having large color differences in color movement relative to nearby pixels in the color difference map, by applying an edge-detection algorithm to the color difference map to identify edge areas of the color difference map for which pixels in the color difference map have large differences of color movement relative to nearby pixels, and smooth areas of the color difference map for which pixels do not have large differences of color movement relative to nearby pixels;
• and
• for each pixel that is identified in a smooth area in the original image and is identified as having a large color difference in the color difference map, apply a correction algorithm, so as to provide a corrected color mapped image.

A computer-readable memory medium on which is stored computer-executable process steps for causing a computer to perform image color mapping of an original image represented as an array of a plurality of pixels, said process steps comprising:

• transforming the original image using a color mapping algorithm to generate a color mapped image;
• identifying pixels in smooth areas in the original image by applying an edge-detection algorithm that detects pixels in edge areas and pixels in smooth areas of the original image;
• generating a color difference map between the color mapped image and the original image, wherein the color difference map is comprised of color difference vectors for each of the plurality of pixels of the original image, wherein the color difference vector for each pixel includes both a magnitude and a directionality representing a difference for color data in each pixel in the original image, relative to color data in a corresponding mapped pixel in the color mapped image;
• identifying pixels in the color difference map having large color differences in color movement relative to nearby pixels in the color difference map, by applying an edge-detection algorithm to the color difference map to identify edge areas of the color difference map for which pixels in the color difference map have large differences of color movement relative to nearby pixels, and smooth areas of the color difference map for which pixels do not have large differences of color movement relative to nearby pixels;
• and
• for each pixel that is identified in a smooth area in the original image and is identified as having a large color difference in the color difference map, applying a correction algorithm, so as to provide a corrected color mapped image.