The present invention is directed to a system and method for processing an image. More specifically, the present invention is directed to a method of generating additive primary colors from PostScript code to drive a visual display.
A primary application of the PostScript language is to describe the appearance of text, graphical shapes, and sampled images on printed or displayed pages according to the Adobe imaging model. More specifically, a program in the PostScript language communicates a description of an image or document from a composition system to a printing system or control the appearance of text and graphics on a display. Within the PostScript language, colors are suitably specified in a variety of ways including: grayscale, red, green, and blue (RGB), cyan, magenta, yellow, and black (CMYK), and Commission Internationale de l'Eclairage-based (CIELab).
Furthermore, a duotone is the result of a method to colorize a grayscale image or to create a visual special effect. The term “duotone” refers to an image reproduced with two colorants. A duotone differs from a spot color. A spot color is defined by coordinates in a color space. In contrast, a duotone is defined by either a vector from a white point to the maximum saturation value defined by the spot color coordinates in that color space, a plane defined by the vector of two colors, or, in the case of three or more spot colors, a three dimensional gamut defined by the vector of the three spot colors from white to each saturation value.
Duotone use represents one of the more difficult color reproductions in image generation, particularly in the values of each colorant used. In addition to duoton, monotones, one color, tritons, three colors, and quadtones, four colors, are also known for image generation. The term quadtone is often times confusing. In some instances, a quadtone refers to an image reproduced with four spot colorants. In other instances, a quadtone is used by photographers to describe images produced in 4, 6, and 7 shades of black and gray colorants on an inkjet printer or offset press. As used herein, the term duotone will be used to refer to an image produced with any number of colorants.
As mentioned, an original intent of the PostScript language, and of a duotone, is to prepare data contained in a grayscale image for reproduction with user selected colorants, such as a number of black and spot or match colorants. However, it is also useful to prepare these images for reproduction on printers having cyan, magenta, yellow, and black (CMYK) colorants and for display on red, green, and blue (RGB) monitors. Therefore, a conversion from named colorants to device colorants is desirous. Moreover, there is a need for a system and method for generating additive primaries for visual display, such as in a monitor with red, green, and blue (RGB) data being generated from PostScript code.