Method for determining the color of a scene illuminant from a color image
First Claim
1. A method for determining the color of a scene illuminant from a color photographic image, of a scene containing a plurality of differently colored specularly reflecting surfaces, comprising the steps of:
- scanning the color photographic image to produce a digital color image;
transforming the digital color image to a chromaticity space; and
processing the transformed digital color image to detect the color of specularly reflected light in the scene, the color of the specularly reflected light corresponding to the color of the scene illuminant.
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Abstract
A method of determining the color of light employed to illuminate the scene in a color image from the image itself, relies upon detecting the color of the specularly reflected light in the image. In a preferred mode of practicing the invention, the color of specularly reflected light is detected by detecting a plurality of sets of points having constant hue and varying saturation on a plurality of differently colored surfaces in the scene, and determining the locus of the intersection of straight lines fit through the color values of the sets of points. The locus of the intersection of the straight lines indicates the color of the scene illuminant. In an application of the method in a color printer, the determined illuminant color is employed as the aim point in the photographic printing process.
122 Citations
13 Claims
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1. A method for determining the color of a scene illuminant from a color photographic image, of a scene containing a plurality of differently colored specularly reflecting surfaces, comprising the steps of:
- scanning the color photographic image to produce a digital color image;
transforming the digital color image to a chromaticity space; and
processing the transformed digital color image to detect the color of specularly reflected light in the scene, the color of the specularly reflected light corresponding to the color of the scene illuminant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- scanning the color photographic image to produce a digital color image;
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10. A method of reproducing a color photographic image of a scene containing a plurality of different colored specularly reflective surfaces comprising the steps of:
scanning the color photographic image to produce a digital color image;
transforming the digital color image to a chromaticity space;
processing the transformed digital color image to determine the color of a scene illuminant by determining the color of specularly reflected light in the scene;
printing the photographic image using a printing process employing color correction toward an aim point; and
employing the illuminant color as the aim point.- View Dependent Claims (11)
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12. A method of scan printing a color photographic image of a scene containing a plurality of differently colored specularly reflective surfaces comprising the steps of:
scanning the color photographic image to produce a digital color image;
transforming the digital color image to a chromaticity space;
processing the transformed digital color image to determine the color of a scene illuminant by determining the color of specularly reflected light in a plurality of local areas of the digital color image;
processing the digital color image, employing the color of scene illuminant determined for local areas of the image to color correct the digital color image in said local areas; and
scan printing the digital color image.- View Dependent Claims (13)
Specification