Horizontal image expansion system for flat panel displays

Abstract

A system for horizontal expansion of low resolution display modes onto high resolution displays including flat panels at a variable scaling factor is disclosed. The system may be combined with known methods for vertical expansion to allow low resolution display modes to be expanded onto any high resolution display. Two different methods are provided, one for graphics modes and one for text modes, to attain better screen image quality. In the first method, a first pixel data sequence to be expanded is first oversampled at a multiple of the frequency thereof to produce an intermediate oversampled data sequence. The oversampled data sequence is linearly decimated by a factor of less than unity to produce a replicated second data sequence longer than the first, which is then displayed. In the second method, the intermediate oversampled data sequence is filtered to provide an interpolated oversampled data sequence, which is then decimated instead of the intermediate oversampled data sequence, to further improve the screen image quality. No particular mechanism for the graphics controller or display logic is required, eliminating complicated image processing and enabling the size, complexity and cost of the video subsystem of a computer to be reduced.