| 摘要 |
A process for producing a skeleton from a raster image by overlaying a plurality of tiles on the raster image, wherein each of the tiles identifies a sub-region of the raster image comprised of a plurality of pixels. The sub-regions are selectively skeletonized and then cached for subsequent access. Some or all of the cache is invalidated when one or more of the sub-regions are modified. Only those sub-regions that have been modified are re-skeletonized, on an "as needed" basis.
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