Method and apparatus for bezier curve approximation data compression
OwnerJaehwa Park, Manjirnath Chatterjee +1inventors
InventorsJaehwa Park, Manjirnath Chatterjee, Charles Wang
Life of this patent
Estimating the term…
Abstract
A method (400) and apparatus (1000) for compressing digital ink such as a hand-drawn object (104) are provided. The hand-drawn object is first prepared (406, 1010) and then Bezier curves based upon the hand-drawn object are generated (408, 1012). The Bezier curve representation (202) of the hand-drawn object (104) is further compressed (418, 1018) by modifying Bezier control points to produce a compressed Bezier curve representation (302) of the hand-drawn object (104).
Claims27
A method in an electronic device for compressing digital ink, the digital ink comprising a plurality of digital ink points representing a drawn object on a display, the method comprising:
- dividing the digital ink into a plurality of digital ink strokes;
- representing each of the plurality of digital ink strokes with a corresponding approximation element based upon quadratic Bezier curve approximation, the corresponding approximation element comprising an element identification and Bezier control points;
- separating the corresponding approximation elements of the plurality of digital ink strokes into first and second groups of approximation elements based upon a first predetermined condition, the first group of approximation elements satisfying the first predetermined condition and the second group of approximation elements not satisfying the first predetermined condition;
- converting each approximation element of the first group of approximation elements into a corresponding line approximation segment to obtain a converted first group of elements;
- and
- re-representing each approximation element of the second group of approximation elements based upon a second predetermined condition to obtain a re-represented second group of elements.
An electronic device capable of compressing digital ink representing a drawn object, the electronic device comprising:
- a display configured to display the drawn object;
- a processor coupled to the display, the processor configured to capture the drawn object on the display as digital ink;
- and
- a memory circuit coupled to the processor,
- wherein the processor comprises:
- a digital ink stroke generator configured to divide the digital ink into a plurality of digital ink strokes;
- a Bezier curve generator coupled to the digital ink stroke generator, the Bezier curve generator configured to generate Bezier control points based upon quadratic Bezier curve approximation, the Bezier control points representing approximation elements, each approximation element having a unique corresponding digital ink stroke in the plurality of digital ink strokes;
- an element separator coupled to the Bezier curve generator, the element separator configured to separate the approximation elements into first and second groups based upon a first predetermined condition;
- a line converter coupled to the element separator, the line converter configured to convert each approximation element of the first group into a corresponding line approximation segment;
- a modifier coupled to the element separator, the modifier configured to re-represent each approximation element of the second group based upon a second predetermined condition;
- and
- a data compressor coupled to the line converter and the modifier, the data compressor configured to compress a combined data of the converted first group and the re-represented second group.
A method in an electronic device for compressing a Bezier curve approximation, the Bezier curve approximation having a plurality of approximation elements, each approximation element represented by corresponding Bezier control points comprising first and second on-line control points and an off-line control point, each approximation element identified by an element identification, the method comprising:
- separating the plurality of approximation elements into first and second groups of approximation elements based upon a first predetermined condition, the first group of approximation elements satisfying the first predetermined condition and the second group of approximation elements not satisfying the first predetermined condition;
- converting each approximation element of the first group of approximation elements into a corresponding line approximation segment to obtain a converted first group of elements;
- re-representing each approximation element of the second group of approximation elements based upon a second predetermined condition to obtain a re-represented second group of elements;
- and
- compressing losslessly the converted first group of approximation elements and the re-represented second group of approximation elements.
Dependencies are inferred from the claim text.