| 摘要 |
A method is described for printing a colorant controlled neutral black object in a bitmap-based digital color printing system. The method is useful in systems where the black colorant is not sufficiently opaque to hide non-neutral combinations of non-black colorants mixed into the black color. Black colors in a color printing system can be composed either of black colorant only or of black plus non-black colorants such as cyan, magenta, and yellow. If the non-black colorants are not mixed in nearly equal quantities, they will add hue to the black color. A sufficiently opaque black colorant can hide this objectionable non-black hue. However, in cases where the black colorant is not opaque enough, it is important to use equal or nearly equal combinations of cyan, magenta, and yellow so that little net hue will be introduced into the black color. Equally important in some printing systems is the ability to control the amount of total colorant used in forming a process black color. The invention proposes an efficient method for producing a colorant controlled, neutral black color when merging a black object into a color background for printing. The method involves reading the existing non-black background bits into a buffer, mixing them together and masking them to reduce the total colorant amount, or counting the ON bits and choosing a table entry based on this total, and outputting them again to the bitmap for printing.
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