Jeffrey Kempf - Dallas TX,
Rashmi Vijayaraghavan - Plano TX,
Donald Doherty - Richardson TX,
382274000, 353069000, 353070000
A digital circuit, system, and method for keystone correction of a projected image utilize a digital compensation engine to resize a digital image prior to projection. Preferred embodiments of the present invention utilize a compensation engine with a separable architecture in which the two-dimensional image-resizing task is partitioned to use two engines. Horizontal image resizing is performed first, followed by vertical image resizing. Two large polyphase, anti-aliasing, finite impulse response (“FIR”) filters are used to resize the data. A 639-tap filter is used for horizontal resizing, and a 383-tap filter for vertical resizing. Pixels in the corrected image can be positioned with arbitrary accuracy to avoid forming stair-stepped lines in the corrected image. The coefficients for the FIR filters can be stored with 10-bit precision to provide a resized image without loss of visible quality. The compensation engine can be readily configured with an ASIC device or in software.