Pixel color modification using look-up tables in image reproduction system
First Claim
1. Apparatus for modifying colours in image reproduction systems, including:
- means for providing digital signals corresponding to the values of colour components of an image to be reproduced;
a set of look-up tables to which the respective colour component signal values of each pixel are applied and which, according to the colour component signal values, provide digital output signals indicating whether a processing operation is to be carried out for that pixel, said digital output signals defining one of a plurality of possible processing operations;
and control means capable of carrying out any one of the said plurality of possible processing operations, said control means being responsive to the output signals from the look-up tables for selecting and carrying out the defined processing operation on the current pixel colour component signals.
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Accused Products
Abstract
Digital signals are generated for each pixel of an image to be reproduced, corresponding to the values of color components in each pixel. The respective color component values of each pixel are applied to a set of look-up tables (30) so loaded that they recognize whether the color component values of a pixel fall within a color range(s) for which a processing operation is to be carried out. The look-up tables provide an output signal representing one of a number of possible processing operations for that pixel, in the form of an operation number. The operation number signal is applied through a processor (32) to an operation select table (36) which converts the operation number into a specific processing operation for each color component. The processing operations may be retouching, image retention (no change), replacement by a tint value, or dropout. They are carried out by components (44, 42, 38 and 40) under the control of the operation select table, and the resulting pixel values are transferred to an output buffer (24). The look-up tables may define the color ranges within which processing operations are required in terms of a range of a single color component or coinciding ranges of 2, 3 or 4 color components.
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Citations
10 Claims
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1. Apparatus for modifying colours in image reproduction systems, including:
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means for providing digital signals corresponding to the values of colour components of an image to be reproduced; a set of look-up tables to which the respective colour component signal values of each pixel are applied and which, according to the colour component signal values, provide digital output signals indicating whether a processing operation is to be carried out for that pixel, said digital output signals defining one of a plurality of possible processing operations; and control means capable of carrying out any one of the said plurality of possible processing operations, said control means being responsive to the output signals from the look-up tables for selecting and carrying out the defined processing operation on the current pixel colour component signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification