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.
The invention relates to a method for applying colors by subdividing the colors according to percentages allocated to each of the printing points which are, for example, divided centesimally in accordance with a rule which defines the distribution of appropriately superimposed basic colors, thereby creating binaries and blacks according to the subtraction of the percentage of the basic color most used percentually from the sum of basic colors less used percentually. Thus, the totality of visible colors are optically generated. The background of the surface to be printed is previously analyzed and the percentage quantity in each point of the based colors is deducted in the proportion contained in the background. The application of pigments is carried out by addition of transparent substrate or medium or while, until the proportion of each color is completed.
An adjusting dot position method for overlapped dots in a printer is disclosed. The pixels of an image are first input. Then, it determines whether the pixel is an overlapped dot or not. If yes and a pixel on a left side is a blank dot, the magenta, cyan or yellow in the pixel is moved to the left side pixel. Then, it determines whether the pixel is an overlapped dot or not. If yes and a pixel on an upper side is a blank dot, the magenta, cyan or yellow dot in the pixel is moved to the upper side pixel.
A method for mapping a color specification to colorant amounts when a first and a second colorant have a similar hue involves the division of portions of color space into regions. Colors of the similar hue are rendered with a first colorant, a second colorant or a blend of the first and second colorants depending on which region of a color specification space the color specification is related. An image processor operative to map color descriptions via the method includes a colorant splitters operative to map a color description to colorant amounts for colorants of similar hue. In a xerographic environment, such an image processor includes a xerographic printer.
In a system for processing full-color image data, such as within a digital color printer or copier, a four-channel architecture is used. Three of the channels handle image data relating to primary color planes, such as CMY. In the other channel, values relating to the K value which goes with the CMY values for each pixel alternate with a B value, suitable for pure monochrome rendering of the pixel in the image. When it is desired to print or display the image in monochrome, the B values are isolated from the K values.
