Page buffer system for an electronic gray-scale color printer

Abstract

A data storage system for an electronic color printer which stores data according to the type of information the data represents. When the data represents area fill and image information, the data is stored in the page buffer according to mode A of the invention wherein a plurality of pixels are all defined to have the same color with varying luminance levels. This color is defined in the memory in a uniform color space format. When the data to be stored is representing text or line graphics information, the data is stored in the page buffer according to mode B of the invention. In mode B, two-bit binary values in the page buffer are assigned to each pixel of a multiple-pixel cell. These two-bit values point to additional bytes in the memory block of the page buffer which in turn point to discrete colors in spectrums of 256 colors. Additional data indicates whether the output device is to reproduce the colors by halftoned or non-halftoned techniques. Thus, each pixel within the pixel cell can be printed in a color selected by the color portion of the page buffer. According to mode C of the invention, three separate color maps are defined in binary form by the bit patterns stored in the page buffer memory. Also in mode C, the method used to produce blacks in the output page is specified. By standardizing on the memory allocated to the page and utilizing this memory in different ways according to the nature of the inputted information, the printed page can be accurately stored with a minimum of memory space and without a reduction in perceived printing quality.