Graphics Gems III (IBM Version)

1.3

OPTIMIZATION OF BITMAP SCALING OPERATIONS

Dale Schumacher,     St Paul, Minnesota

Publisher Summary

This chapter describes a series of optimizations for bitmap-scaling operations and discusses several application-specific constraints that allow significant reductions in execution time: single-bit per pixel images, known source and destination-bitmap sizes, and bit-packed horizontal raster storage and display formats. The example application is the display of fax bitmap images on typical video monitors. The heart of the algorithm is the reduction lookup table. If there is a need to reverse black and white in the final image, one way to do it is to invert the bits stored in the lookup table. Then, instead of 00000000b mapping to 00000b, ...