Filtering by repeated integration
SIGGRAPH '86 Proceedings of the 13th annual conference on Computer graphics and interactive techniques
Digital image processing
A language for bitmap manipulation
ACM Transactions on Graphics (TOG)
Heuristics for minimum edge length rectangular partitions of rectilinear figures
Proceedings of the 6th GI-Conference on Theoretical Computer Science
SIGGRAPH '83 Proceedings of the 10th annual conference on Computer graphics and interactive techniques
Filtering high quality text for display on raster scan devices
SIGGRAPH '81 Proceedings of the 8th annual conference on Computer graphics and interactive techniques
The use of grayscale for improved raster display of vectors and characters
SIGGRAPH '78 Proceedings of the 5th annual conference on Computer graphics and interactive techniques
A tutorial on compensation tables
SIGGRAPH '79 Proceedings of the 6th annual conference on Computer graphics and interactive techniques
The display of characters using gray level sample arrays
SIGGRAPH '80 Proceedings of the 7th annual conference on Computer graphics and interactive techniques
Human vision, anti-aliasing, and the cheap 4000 line display
SIGGRAPH '80 Proceedings of the 7th annual conference on Computer graphics and interactive techniques
Summed-area tables for texture mapping
SIGGRAPH '84 Proceedings of the 11th annual conference on Computer graphics and interactive techniques
Antialiased ray tracing by adaptive progressive refinement
SIGGRAPH '89 Proceedings of the 16th annual conference on Computer graphics and interactive techniques
Antialiasing of curves by discrete pre-filtering
Proceedings of the 24th annual conference on Computer graphics and interactive techniques
Constant-time filtering with space-variant kernels
SIGGRAPH '88 Proceedings of the 15th annual conference on Computer graphics and interactive techniques
Perceptually Tuned Generation of Grayscale Fonts
IEEE Computer Graphics and Applications
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While the race towards higher-resolution bitmap displays is still on, many grayscale displays have appeared on the scene. To fully utilize their capabilities, grayscale fonts are needed, and these can be produced by filtering bi-level masters. Most of the efficient filtering techniques cannot directly be applied. For example, prefiltering is impractical, due to the number of character masters and the requirement of sub-pixel positioning. Furthermore, we would like to impose as few restrictions as possible on the characteristics of the filter, in order to facilitate exploration into the quality of various filters.We describe a fast filtering technique especially adapted to this task. The characters are decomposed into rectangles, and a summed-area representation of the filter is efficiently convolved with each individual rectangle to construct the grayscale character. For a given filter, the number of operations is O (linear size of the grayscale character), which is optimal.We give an analysis of the efficiency of this technique, and examples of its implementation applied to various families of fonts and point sizes. The performance of the implementation is such that filtering characters for grayscale displays is feasible in realtime on personal workstations.