Method and apparatus for improving the definition of black and white text and graphics on a color matrix digital display device

Abstract

A digital signal processing (DSP) method to process rendered text in order to achieve up to 300% of the horizontal resolution on any suitable digital display devices such as LCD, PDP and DLP. When the text is rendered, a single picture element (a “pixel”) of a matrix display screen is actually composed of three “sub-pixels”: one red, one green, and one blue (RGB or BGR). Taken together this sub-pixel triplet makes up what has been traditionally thought of as a single pixel. By staggering and processing the sub-pixel elements horizontally, font resolution is effectively increased to the maximum of 300%. There are three processing steps involved. First, the color image is expanded to a gray scale image having triple the number of horizontal pixels as the original image by interleaving the sub-pixels. Next, a black and white text/graphics (TG) detector is deployed to identify the TG of interest in the gray scale image. Then, the, detected TG and only the detected TG is subject to a morphological thinning operation so that the TG approximates fonts (or graphics) that would be generated from a sub-pixel rendering engine. Finally, the processed TG display data is filtered to minimize color fringing while maximizing its resolution. The resulting display data including the processed TG data and the unprocessed color signals are converted back to the sub-pixels (e.g., RGB or BGR) domain and displayed.