Stroke-to-stroke

• US 5,969,699 A
• Filed: 06/30/1997
• Issued: 10/19/1999
• Est. Priority Date: 10/08/1996
• Status: Expired due to Fees

• Current Assignee: Kaiser Aerospace & Electronics Corporation, Kaiser Electronics Co., Ltd.
• Original Assignee: Kaiser Aerospace & Electronics Corporation
• Inventors: Wilson, Michael R., Olson, William P., Balram, Nikhil
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Frenel, Vanel
• Application Number:
  US08/885,363
• Time in Patent Office: 841 Days
• Field of Search: 345/10, 345/16, 345/17, 345/136
• US Class Current: 345/10
• CPC Class Codes: G09G 5/393 Arrangements for updating the contents of the bit-mapped memory

Abstract

A digital address filter is provided which converts straight-line and arc analog stroke data into digitized images which comply with Bresenham raster display criteria and can be displayed on a raster scanned monitor or LCD. Data collected over a preselected (M pixel×M pixel) spatial window are repetitively matched against a set of pixel template patterns permitted by the Bresenham criteria. After each full-frame iteration, the display pixel(s) corresponding to the best-fit templates are lighted.

Claims

1. A method of converting stroke display data to raster scan display data comprising the following steps:

writing a selected pixel to a frame buffer;

locating an extended pixel matrix in a fixed relationship to said selected pixel;

sampling stroke display data to count occurrences of sample addresses within said extended pixel matrix; and

comparing a pattern of sample address counts against a predetermined set of acceptable address patterns to select a pixel to be a next selected pixel.

2. The method of claim 1 further comprising the step of:

repeating the preceding steps until a stroke segment end is detected, or raster mode is selected.

3. The method of claim 2 wherein:

the steps are done in real-time.

4. The method of claim 3 or claim 2 further comprising the step of:

monitoring the count of occurrences of sample addresses in the extended pixel matrix during sampling to determine when to begin comparing.

5. The method of claim 4 wherein the step of monitoring the count of occurrences of sample addresses in the extended pixel matrix during sampling further comprises the step of:

determining to begin comparing when the total sample address count in the pixel matrix reaches a first predetermined level or when a stroke segment end is detected.

6. The method of claim 5 wherein the step of determining to begin comparing when a stroke segment end is detected further comprises the step of:

monitoring the count of occurrences of sample addresses in a series of subsets of the extended pixel matrix.

7. The method of claim 6 wherein the step of determining to begin comparing when a stroke segment end is detected comprises the step of:

determining to begin comparing when the total count of occurrences of sample addresses in one of the series subsets of the extended pixel matrix reaches a second predetermined level.

8. The method of claim 7 wherein each subset is a pixel.

9. The method of claim 7 wherein the step of comparing a pattern of sample address counts against a predetermined set of acceptable address patterns to select a pixel to be the next selected pixel further comprises the steps of:

selecting an acceptable address pattern having the closest density match to said pattern of sample address counts; and

writing every pixel of said acceptable address pattern to said frame buffer.

10. The method of claim 9 further comprising the steps of:

clearing sample data from the extended pixel matrix; and

selecting a selected pixel to define the extended pixel matrix based on a preselected number of sample addresses.

11. The method of claim 4 further comprising the steps of:

locating an active pixel matrix in a fixed relationship to said selected pixel, such that said active pixel matrix contains a subset of extended pixel matrix sample addresses;

storing a sample address count for sample addresses within said active pixel matrix; and

comparing a pattern of sample address counts within said active pixel matrix against a predetermined set of acceptable address patterns to select a pixel to be a next selected pixel.

12. The method of claim 11 wherein the step of comparing said pattern of sample address counts within said active pixel matrix against a predetermined set of acceptable address patterns further comprises the step of:

analyzing the magnitude of sample address counts in said active pixel matrix to select a selected subset of said active pixel matrix to be compared against said predetermined set of acceptable address patterns.

13. The method of claim 12 wherein the step of analyzing the sample density in the active pixel matrix to select a selected subset further comprises the step of:

selecting said selected subset having the greatest magnitude of sample address counts.

14. The method of claim 13 wherein the step of selecting said selected subset having the greatest density further comprises the steps of:

analyzing sub-portions of each subset to determine which sub-portion or sub-portions have the greatest magnitude of sample address counts; and

selecting a selected subset including a sub-portion or sub-portions having the greatest magnitude of sample address counts.

15. The method of claim 12 wherein the step of comparing said pattern of sample address counts against a predetermined set of acceptable address patterns further comprises the step of:

transforming said selected subset of said active pixel matrix relative to said set of acceptable address patterns to reduce the comparing required.

16. The method of claim 15 wherein the step of comparing said pattern of sample address counts against a predetermined set of acceptable address patterns further comprises the step of:

selecting an acceptable address pattern having the closest density match to said selected subset.

17. The method of claim 16 wherein the step of selecting a subsequent selected pixel further comprises the step of:

retransforming said selected acceptable address pattern to match the original orientation of said selected subset or said selected hitmap.

18. The method of claim 17 wherein the step of selecting a pixel to be a next selected pixel further comprises the steps of:

selecting said next selected pixel to be a pixel of said acceptable address pattern adjacent to the selected pixel to which the extended pixel matrix and the active pixel matrix are related.

19. The method of claim 18 wherein the step of selecting a pixel to be the next selected pixel further comprises the step of:

clearing sample data from a portion of the extended pixel matrix and the active pixel matrix, based on the next selected pixel.

20. The method of claim 12 wherein the subset of the active pixel matrix comprises:

a hitmap of the active pixel matrix such that said hitmap includes said selected pixel.

21. The method of claim 20 wherein the step of analyzing said magnitude of sample address counts in said active pixel matrix to select a hitmap further comprises the step of:

selecting said hitmap having the greatest magnitude of sample address counts.

22. The method of claim 21 wherein the step of selecting said hitmap having the greatest density further comprises the steps of:

analyzing octants of said active pixel matrix to determine an octant or octants having the greatest magnitude of sample address counts; and

selecting a selected hitmap of said active pixel matrix including said octant or octants having the greatest magnitude of sample address counts.

23. The method of claim 22 wherein the step of comparing said pattern of sample address counts against a predetermined set of acceptable address patterns further comprises the step of:

transforming said selected hitmap relative to said set of acceptable address patterns to reduce the comparing required.

24. The method of claim 23 wherein the step of comparing said pattern of sample address counts against a predetermined set of acceptable address patterns further comprises the step of:

selecting an acceptable address pattern having the closest pattern match to said selected hitmap.

25. The method of claim 24 wherein the step of selecting a subsequent selected pixel further comprises the step of:

retransforming said selected acceptable address pattern to match the original orientation of said selected subset or said selected hitmap.

26. The method of claim 25 wherein the step of selecting a pixel to be a next selected pixel further comprises the steps of:

selecting said next selected pixel to be a pixel of said acceptable address pattern adjacent to the selected pixel to which the extended pixel matrix and the active pixel matrix are related.

27. The method of claim 26 wherein the step of selecting a pixel to be the next selected pixel further comprises the step of:

clearing sample data from a portion of the extended pixel matrix and the active pixel matrix, based on the next selected pixel.

28. The method of claim 11 wherein the step of monitoring the sample address count in the extended pixel matrix during sampling to determine when to begin comparing further comprises the step of:

copying said pattern of sample address counts from said extended pixel matrix to said active area pixel matrix prior to beginning comparing.

29. The method of claim 1 further comprising the step of:

selecting a selected pixel to define the extended pixel matrix based on a preselected number of sample addresses.

30. A stroke to raster display converter comprising:

means for converting an analog input data stream to a stream of digital pixel addresses;

an extended pixel matrix of pixel address counters;

means for sampling the stroke display data to count occurrences of sample addresses within said extended pixel matrix;

means for comparing a pattern of sample address counts against a predetermined set of acceptable address patterns to select a subsequent selected pixel;

raster frame buffer for storing each subsequent selected pixel; and

means for illuminating said subsequent selected pixels in said raster frame buffer.

31. The device of claim 30 further comprising:

means for monitoring the sample address count in the extended pixel matrix during sampling to determine when to begin comparing.

32. The device of claim 31 further comprising:

means for monitoring the sample address count in a series of subsets of the extended pixel matrix.

33. The device of claim 32 further comprising:

means for determining to begin comparing when the total sample address count in one of the series subsets of the extended pixel matrix reaches a second predetermined level.

34. The device of claim 31 further comprising:

an active pixel matrix of data registers in a fixed relationship to said selected pixel, such that said active pixel matrix contains fewer sample addresses than said extended pixel matrix; and

means for comparing a pattern of sample address counts within said active pixel matrix registers against a predetermined set of acceptable address patterns to select a subsequent selected pixel.

35. The device of claim 34 further comprising:

means for analyzing the magnitude of sample address counts in said active pixel matrix to select a selected subset of said active pixel matrix to be compared against said predetermined set of acceptable address patterns.

36. The device of claim 35 further comprising:

means for selecting said selected subset having the greatest magnitude of sample address counts.

37. The device of claim 36 further comprising:

means for analyzing sub-portions of each subset to determine which sub-portion or sub-portions have the greatest magnitude of sample address counts; and

means for selecting a selected subset including a sub-portion or sub-portions having the greatest magnitude of sample address counts.

38. The device of claim 37 further comprising:

means for transforming said selected subset of said active pixel matrix relative to said set of acceptable address patterns to reduce the comparing required.

39. The device of claim 38 further comprising:

means for selecting an acceptable address pattern having the closest density match to said selected subset.

40. The device of claim 31 further comprising:

means for clearing sample data from a portion of the extended pixel matrix and the active pixel matrix, based on the subsequent selected pixel.

41. The device of claim 31 further comprising:

means for selecting a selected pixel to define the extended pixel matrix based on a preselected number of sample addresses.