Apparatus and method for enhancing color saturation in halftoned images
AssigneeSeiko Epson Corporation
InventorJoseph S. Shu
Life of this patent
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Abstract
Adaptive preprocessing is performed on the three primary color signals generated during the scanning of a color image in order to enhance the perceived saturation of the dominant primary color. This preprocessing is performed by removing a small increment from the least intense primary color and adding the same increment to the most intense primary color. In this manner the overall brightness of the pixel is preserved, but the perceived saturation is increased. The increment that is effectively transferred from the least intense primary color value to the most intense primary color value is based on the relations of the three primary color values to each other in order to avoid visible color artifacts.
Claims24
Apparatus for enhancing color saturation in a halftone image comprised of a plurality of pixels, each pixel having a color comprised of three primary color values, the apparatus processing each of the plurality of pixels and comprising:
- means responsive to the three primary color values of a pixel for selecting the maximum primary color value;
- means responsive to the three primary color values of a pixel for selecting the minimum primary color value;
- and
- means responsive to the maximum primary color value and the minimum primary color value for subtracting an incremental amount from the minimum primary color value and adding the incremental amount to the maximum primary color value, the incremental amount being dependent on the maximum primary color value and the minimum primary color value and being determined in order to minimize visual artifacts in the halftone image.
Apparatus for enhancing color saturation in a halftone image comprised of a plurality of pixels, each pixel having a color comprised of three primary color values, the apparatus processing each of the plurality of pixels and comprising:
- a minimum circuit responsive to the three primary color values of a pixel for selecting the maximum primary color value;
- a maximum circuit responsive to the three primary color values of the pixel for selecting the minimum primary color value;
- an averaging circuit responsive to the three primary color values of the pixel for calculating an average primary color value;
- means responsive to the maximum primary color value, the minimum primary color value and the average primary color value for calculating an incremental amount, the incremental amount being dependent on the maximum primary color value and the minimum primary color value and the average primary color value and being determined in order to minimize visual artifacts in the halftone image;
- a subtractor responsive to the incremental amount for subtracting the incremental amount from the minimum primary color value;
- and
- an adder responsive to the incremental amount for adding the incremental amount to the maximum primary color value.
A method for enhancing color saturation in a halftone image comprised of a plurality of pixels, each pixel having a color comprised of three primary color values, the method processing each of the plurality of pixels and comprising the steps of:
- A. selecting the maximum primary color value of the three primary color values of a pixel;
- B. selecting the minimum primary color value of the three primary color values of the pixel;
- and
- C. subtracting an incremental amount from the minimum primary color value and adding the incremental amount to the maximum primary color value, the incremental amount being dependent on the maximum primary color value and the minimum primary color value and being determined in order to minimize visual artifacts in the halftone image.
A method for enhancing color saturation in a halftone image comprised of a plurality of pixels, each pixel having a color comprised of three primary color values, the method processing each of the plurality of pixels and comprising the steps of:
- A. selecting the maximum primary color value of the three primary color values of a pixel;
- B. selecting the minimum primary color value of the three primary color values of the pixel;
- C. calculating an average primary color value of the three primary color values of the pixel;
- D. calculating an incremental amount based on the maximum primary color value, the minimum primary color value and the average primary color value, the incremental amount being dependent on the maximum primary color value and the minimum primary color value and the average primary color value and being determined in order to minimize visual artifacts in the halftone image;
- E. subtracting the incremental amount from the minimum primary color value;
- and
- F. adding the incremental amount to the maximum primary color value.
Dependencies are inferred from the claim text.