Method for generating vector data for a hand-drawn curve

• US 7,116,844 B2
• Filed: 08/09/2002
• Issued: 10/03/2006
• Est. Priority Date: 08/09/2002
• Status: Active Grant

• Current Assignee: CELSYS, Inc. (ArtSpark Holdings, Inc.), TEAC Corporation
• Original Assignee: CELSYS, Inc. (ArtSpark Holdings, Inc.)
• Inventors: Ono, Hiroshi, Kawakami, Yosuke
• Primary Examiner(s): WERNER, BRIAN P
• Application Number:
  US10/215,642
• Publication Number:
  US 20040028274A1
• Time in Patent Office: 1,516 Days
• Field of Search: 382/119, 382/120, 178/19.04
• US Class Current: 382/314
• CPC Class Codes: G06V 30/1423 the instrument generating sequences of position coordinates corresponding to handwriting preprocessing or recognising digital ink G06V30/32

Abstract

The present invention relates to obtaining vector data for a hand-drawn curve having coordinate values input from a pointing device and a thickness and/or density in accordance with pen pressure values. In order to reduce the amount of data input from the pointing device and obtain vector data therefor in real time, the coordinate data and pen pressure data are extracted independently of each other so as to reduce the amount of data stored in a memory and used for plotting or display.

Claims

1. A method for obtaining vector data for a hand-drawn curve, comprising:

a step of receiving and storing in a temporary memory coordinate data and pen pressure data representing points of a hand-drawn path obtained from a pointing device;

a first extraction step of extracting from the coordinate data stored in the temporary memory coordinate characteristic points indicating characteristics of the path;

a coordinate data storage step of storing the coordinate characteristic points into a first storage means;

a second extraction step of extracting pen pressure characteristic points characterizing changes in pen pressure from the pen pressure data stored in the temporary memory;

a pen pressure data storage step of storing the pen pressure characteristic points into a second storage means; and

a plotting processing step of using the coordinate characteristic points stored in the first storage means and the pen pressure characteristic points stored in the second storage means to calculate a curve along which the thickness or density thereof changes in response to the pen pressure,

wherein the first and second extraction steps are carried out independently of each other.

2. The method according to claim 1, further comprising a step, performed before the first and second extraction steps, of performing jitter reduction processing with respect to the coordinate data and pen pressure data stored in the temporary memory.

3. The method according to claim 2, wherein the jitter reduction processing is performed for a given point of the path represented by the coordinate data and the pen pressure data by obtaining a weighted average of the coordinates of a plurality of points including the given point, weighted based on distance between each point of the plurality of points and the given point.

4. The method according to claim 1, wherein the second extraction step includes determining that a current pen pressure point of the path represented by the coordinate data and the pen pressure data is a pen pressure characteristic point when a difference between the current pen pressure point and a previous pen pressure characteristic point is greater than a threshold.

5. The method according to claim 4, wherein the first extraction step includes determining that a current coordinate point of the path represented by the coordinate data and the pen pressure data is a coordinate characteristic point when a distance between the current coordinate point and a previous coordinate characteristic point exceeds a criterion.

6. The method according to claim 5, wherein the coordinate characteristic points and the pen pressure characteristic points are related to one another by way of distances among extracted characteristic points.

7. The method according to claim 1, further comprising a third extraction step whereby with respect to one of the coordinate characteristic points obtained by the first extraction step, a further characteristic point extraction operation is performed, the third extraction step being performed before the coordinate data storage step.

8. The method according to claim 1, further comprising additional extraction step whereby with respect to one of the pen pressure characteristic points obtained by the second extraction step, a further characteristic point extraction operation is performed, the additional extraction step being performed before the pen pressure data storage step.

9. The method according to claim 1, wherein the plotting processing step further includes a step of performing interpolation with respect to the coordinate characteristic points and the pen pressure characteristic points, using a spline curve to obtain a curve for plotting or screen display.

10. The method according to claim 1, wherein the plotting processing step further includes a step of performing interpolation with respect to the coordinate characteristic points and the pen pressure characteristic points, using a spline curve to obtain at least one of a line thickness or a density of a curve for plotting or screen display.

11. The method according to claim 1, further comprising the step of, when a capacity of the temporary memory is full, replacing oldest data stored in the temporary memory with newest data, the oldest data and the newest data each including data selected from the group consisting of the pen pressure data and the coordinate data.

12. A computer-readable recording medium having a program encoded thereon, the program being executable by an image processing apparatus, information processing apparatus or a computer to perform a method, said method comprising:

a step of receiving and storing in a temporary memory coordinate data and pen pressure data representing points of a hand-drawn path obtained from a pointing device;

a first extraction step of extracting from the coordinate data stored in the temporary memory coordinate characteristic points indicating characteristics of the path;

a coordinate data storage step of storing the coordinate characteristic points into a first storage means;

a second extraction step of extracting pen pressure characteristic points characterizing changes in pen pressure from the pen pressure data stored in the temporary memory;

a pen pressure data storage step of storing the pen pressure characteristic points into a second storage means; and

a plotting processing step of using the coordinate characteristic points stored in the first storage means and the pen pressure characteristic points stored in the second storage means to calculate a curve along which the thickness or density thereof changes in response to the pen pressure,

wherein the first and second extraction steps are carried out independently of each other.

13. An information processing apparatus, comprising:

a temporary memory operable to store coordinate data and pen pressure data representing points of a hand-drawn path obtained from a pointing device;

means for extracting from the coordinate data stored in the temporary memory coordinate characteristic points indicating characteristics of the path;

first storage means operable to store the coordinate characteristic points;

means f or extracting pen pressure characteristic points characterizing changes in pen pressure from the pen pressure data stored in the temporary memory;

second storage means operable to store the pen pressure characteristic points; and

means for calculating a curve along which the thickness or density thereof changes in response to the pen pressure using the coordinate characteristic points stored in the first storage means and the pen pressure characteristic points stored in the second storage means,

wherein extraction of the coordinate characteristic points by the means for extracting coordinate characteristic points is independent of extraction of the pen pressure characteristic points by the means for extracting pen pressure characteristic points.