Varying hand-drawn line width for display

• US 7,697,002 B2
• Filed: 01/25/2007
• Issued: 04/13/2010
• Est. Priority Date: 01/25/2007
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: McCall, M. Kim, Piersol, Kurt W.
• Primary Examiner(s): Lay; Michelle K
• Application Number:
  US11/626,995
• Publication Number:
  US 20080180410A1
• Time in Patent Office: 1,174 Days
• Field of Search: 715/263, 715/268, 345/467
• US Class Current: 345/467
• CPC Class Codes: G06T 11/203 Drawing of straight lines or curves

Abstract

The present invention overcomes the deficiencies of the prior art with a system for varying hand-drawn line width as a function of geometric or temporal properties such as curvature or time of the strokes as the user draws them. In one embodiment, the system of the present invention includes a stroke control module, a velocity adjustment module, a curvature adjustment module, a smoothing module, an adjacency verification module and a stroke dominance module. A stroke control module is operable on a processor to modify the width of input strokes and adjust them based on their curvature and/or the velocity at which they were received. The stroke control module cooperates with and controls the velocity adjustment module, a curvature adjustment module, the smoothing module and the other modules to provide overall width adjustment of strokes input by the user automatically to reflect the needs and intentions of the user and provide a natural-feeling drawing experience similar to that provided by paper.

Claims

1. A system for varying hand-drawn line width for display, the system comprising:

a processor for receiving a plurality of strokes and processing the plurality of strokes for display;

a display device for displaying hand-drawn lines, the display device coupled to the processor; and

a stroke control module, coupled to the processor, for partitioning the plurality of strokes into a first group of long strokes and a second group of short strokes, the first group of long strokes having a first characteristic and the second group of short strokes having a second characteristic, the first characteristic being different from the second characteristic, the stroke control module partitioning the second group of short strokes into at least one adjacency group, determining a dominance of the at least one adjacency group, and assigning a width to the short strokes in the at least one adjacency group as a function of an average length of the short strokes in the at least one adjacency group.

2. The system of claim 1 wherein the stroke control module is configured for retrieving a selected stroke having a width from the first group of long strokes, and modifying the width of the selected stroke as a function of the first characteristic to provide a desired effect, and consistent with other strokes in the first group of long strokes.

3. The system of claim 2 wherein the stroke control module modifies the width of the selected stroke by varying amounts along a length of the selected stroke.

4. The system of claim 2 wherein the desired effect is that the selected stroke has a paper-like effect.

5. The system of claim 2 wherein the first characteristic is a geometric or temporal property of the selected stroke.

6. The system of claim 2 further comprising a velocity adjustment module for adjusting the width of the selected stroke based on an input velocity at which the selected stroke was input, the velocity adjustment module coupled to the processor.

7. The system of claim 2 further comprising a curvature adjustment module for adjusting the width of the selected stroke based on a curvature of the selected stroke, the curvature adjustment module coupled to the processor.

8. The system of claim 2 wherein the selected stroke includes an interior segment and an end segment, and the system comprising a smoothing module for modifying the selected stroke width to smooth a transition between the end segment and the interior segment, the smoothing module coupled to the processor.

9. The system of claim 1 wherein the stroke control module adaptively modifies the width of the long strokes in the first group or short strokes in the second group based on user context.

10. The system of claim 1 further comprising an adjacency identification module for identifying a first stroke adjacent to a second stroke and adjusting widths of the first and second stroke to be similar, the adjacency identification module coupled to the processor.

11. A method for varying hand-drawn line width for display, the method using a computer to perform steps comprising:

receiving a plurality of strokes;

partitioning using a stroke control module, the plurality of strokes into a first group of long strokes and a second group of short strokes, the first group of long strokes having a first characteristic and the second group of short strokes having a second characteristic, the first characteristic being different from the second characteristic;

partitioning using a stroke control module, the second group of short strokes into at least one adjacency group;

determining a dominance of the at least one adjacency group; and

assigning a width to the short strokes in the at least one adjacency group as a function of an average length of the short strokes in the at least one adjacency group.

12. The method of claim 11 comprising:

retrieving a selected stroke having a width from the first group of long strokes; and

modifying the width of the selected stroke as a function of the first characteristic to provide a desired effect, and consistent with other strokes in the first group of long strokes.

13. The method of claim 12 wherein modifying the width of the selected stroke includes varying the width of the selected stroke by amounts along a length of the selected stroke.

14. The method of claim 12 wherein the desired effect is that the selected stroke has a paper-like effect.

15. The method of claim 12 wherein the first characteristic is a geometric or temporal property of the selected stroke.

16. The method of claim 12, further comprising tapering an end of the selected stroke.

17. The method of claim 12, wherein modifying the width of the selected stroke to provide a desired effect includes modifying the width of the selected stroke as a function of its curvature.

18. The method of claim 12, wherein modifying the width of the selected stroke to provide a desired effect includes modifying the width of the selected stroke as a function of a velocity at which the selected stroke was input.

19. The method of claim 12, wherein modifying the width of the selected stroke to provide a desired effect includes modifying the width of the selected stroke as a function of a velocity at which the selected stroke was input and as a function of its curvature.

20. The method of claim 12, comprising a step of smoothing at least one segment forming the selected stroke.

21. The method of claim 12, wherein the steps of retrieving and modifying are performed in real time with the step of receiving.

22. The method of claim 12, wherein the steps of retrieving and modifying are performed at a predetermined time after the step of receiving.

23. The method of claim 11, comprising:

determining a width of at least one long stroke in an area near the at least one adjacency group; and

assigning a width equal to a width of the long stroke to the group of short strokes in the at least one adjacency group.

24. The method of claim 23, wherein the step of determining the width comprises determining widths of a plurality of long strokes and determining an average of widths of the plurality of long strokes;

and wherein the assigning a width uses the average of the widths.

25. The method of claim 11, wherein partitioning the second group of short strokes into at least one adjacency group is performed by identifying strokes that are temporally or physically nearby other strokes.

26. The method of claim 11, wherein determining dominance of the at least one adjacency group includes:

determining a first total length of the strokes in the at least one adjacency group;

determining a second total length of long strokes in an area near the at least one adjacency group;

setting the at least one adjacency group as dominant if the first total length is greater than the second total length.

27. The method of claim 11, comprising storing the plurality of strokes and re-computing and re-assigning the width of the short strokes based on more complete information about other segments and strokes.