| 摘要 |
<p>This relates to apparatus for modifying colours in image reproduction systems. Digital signals are generated for each pixel of an image to be reproduced, the digital signals corresponding to the values of colour components in each pixel. The respective colour component values of each pixel are applied to a set of look-up tables (30) which are so loaded that they recognise whether the colour component values of a pixel fall within a colour range or colour ranges for which a processing operation is to be carried out. The look-up tables (30) 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 (22) to an operation select table (36) which converts the operation number into a specific processing operation for each colour component. The processing operations may be retouching, image retention (no change), replacement by a tint value or dropout. Means are provided (44, 42, 38 and 40) for carrying out these operations under the control of the operation select table and transferring the resulting pixel values to an output buffer.
<??>The look-up tables (30) may define the colour ranges within which processing operations are required in terms of a range of a single colour component or coinciding ranges of 2, 3 or 4 colour components. </p> |
