OUTLINE FONT COMPRESSION METHOD AND OUTLINE FONT DECOMPRESSION METHOD

Abstract

A difference of coordinate values stored adjacent to each other is compressed by means of a statistical coding system when reading out outline font data storing coordinate values necessary for drawing a contour of a character in order of drawing the contour in a clockwise or counterclockwise direction and also a category of a line connecting a pair of coordinates simultaneously, followed by compressing the coordinate values of the outline font data. A value of a result of subtracting “A−1” from a difference of coordinate values is determined to be a difference value of coordinates if the difference of coordinate value is equal to or greater than a certain value A, and a code expressing the difference value of “0” is added in front of the codes of difference values that are smaller than the value A in the case of a category of line connecting adjacent coordinates to each other being a straight line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a configuration of a conventional outline font compression and decompression system;

FIG. 2 is a diagram showing a common outline font data description method;

FIG. 3 is a configuration diagram of an outline font compression system according to a first embodiment of the present invention;

FIG. 4 is a diagram exemplifying an appearance frequency distribution (of a gothic family font) of difference values related to a straight line and a curve according to the first embodiment of the present invention;

FIG. 5A is a flow chart for describing an operation of an outline font compression system according to the first embodiment of the present invention;

FIG. 5B is a flow chart for describing an operation of an outline font compression system according to the first embodiment of the present invention;

FIG. 5C is a flow chart for describing an operation of an outline font compression system according to the first embodiment of the present invention;

FIG. 5D is a flow chart for describing an operation of an outline font compression system according to the first embodiment of the present invention;

FIG. 6 is a configuration diagram of an outline font decompression system according to a first embodiment of the present invention;

FIG. 7A is a flow chart for describing an operation of an outline font decompression system according to the first embodiment of the present invention;

FIG. 7B is a flow chart for describing an operation of an outline font decompression system according to the first embodiment of the present invention;

FIG. 8 is a configuration diagram of an outline font compression system according to a second embodiment of the present invention;

FIG. 9 is a diagram exemplifying an appearance frequency distribution (of a brush style family font) of difference values related to a straight line and a curve according to the second embodiment of the present invention;

FIG. 10A is a flow chart for describing an operation of an outline font compression system according to the second embodiment of the present invention;

FIG. 10B is a flow chart for describing an operation of an outline font compression system according to the second embodiment of the present invention;

FIG. 10C is a flow chart for describing an operation of an outline font compression system according to the second embodiment of the present invention;

FIG. 10D is a flow chart for describing an operation of an outline font compression system according to the second embodiment of the present invention;

FIG. 10E is a flow chart for describing an operation of an outline font compression system according to the second embodiment of the present invention;

FIG. 11 is a block diagram showing a brief configuration of an outline font decompression system according to the second embodiment of the present invention;

FIG. 12A is a flow chart for describing an operation of an outline font decompression system according to the second embodiment of the present invention;

FIG. 12B is a flow chart for describing an operation of an outline font decompression system according to the second embodiment of the present invention;

FIG. 13 is a configuration diagram of an outline font compression system according to a third embodiment of the present invention;

FIG. 14A is a flow chart for describing an operation of an outline font compression system according to the third embodiment of the present invention;

FIG. 14B is a flow chart for describing a n operation of an outline font compression system according to the third embodiment of the present invention;

FIG. 14C is a flow chart for describing an operation of an outline font compression system according to the third embodiment of the present invention;

FIG. 15 is a configuration diagram of an outline font decompression system according to a third embodiment of the present invention;

FIG. 16A is a flow chart for describing an operation of an outline font decompression system according to the third embodiment of the present invention; and

FIG. 16B is a flow chart for describing an operation of an outline font decompression system according to the third embodiment of the present invention.

Claims

1. An outline font compression method that compresses a difference of coordinate values stored adjacent to each other by means of a statistical coding system when reading out outline font data storing coordinate values necessary for drawing a contour of a character in order of drawing the contour in a clockwise or counterclockwise direction and also a category of a line connecting a pair of coordinates simultaneously, followed by compressing the coordinate values of the outline font data, determining, to be a difference value of coordinates, a value of a result of subtracting “A−1” from a difference of coordinate values if the difference of coordinate values is equal to or greater than a certain value A, andadding a code expressing the difference value of “0” in front of the codes of difference values that are smaller than the value A, in the case of a category of line connecting adjacent coordinates to each other being a straight line.

2. The outline font compression method according to claim 1, determining said certain value A to be a difference value of the highest appearance frequency related to difference values of coordinates of which a category of a line connecting the coordinates to each other is a straight line, and describing the certain value A in a certain spot of outline font data storing the difference value.

3. An outline font decompression method that obtains a coordinate value from data compressed by the outline font compression method according to the claim 1, determining, to be a coordinate value forming a contour, a coordinate value of a result of adding a difference value of decompressed coordinates to one-previous coordinate value if a category of a line is not a straight line;adding a value of a result of adding a value, which is a conversion of a difference value of decompressed coordinates into one prior to being subtracted by “A−1”, to one-previous coordinate value and determining the resultant value to be a coordinate value forming a contour if a category of a line is a straight line and if a difference value of decompressed coordinates is not “0”; anddecompressing a difference value of coordinates stored next in order, adding one-previous coordinate value to the difference value and determining the resultant value to be a coordinate value forming a contour if a category of a line is a straight line and if a difference value of decompressed coordinates is “0”.

4. An outline font compression method that compresses a difference of coordinate values stored adjacent to each other by means of a statistical coding system when reading out outline font data storing coordinate values necessary for drawing a contour of a character in order of drawing the contour in a clockwise or counterclockwise direction and also a category of a line connecting a pair of coordinates simultaneously, followed by compressing the coordinate values of the outline font data, determining, to be a difference value of coordinates, a value of a result of subtracting a value of A from a difference of coordinate values if the difference of coordinate values is greater than a certain value A, andadding a code expressing a difference value of “0” in front of the codes of the difference values in the case of a category of line connecting adjacent coordinates to each other being a straight line.

5. The outline font compression method according to claim 4, wherein said certain value A is determined by a condition of a code length as a result of adding a code length of “0” to a code length corresponding to a value that is a result of subtracting a value A from a value X exceeding the value A being smaller than a code length corresponding to a value X before subtracting the value A therefrom, and describing the value A in a certain spot of outline font data.

6. An outline font decompression method that obtains a coordinate value from data compressed by the outline font compression method according to the claim 4, determining, to be a coordinate value forming a contour, a coordinate value of a result of adding a difference value of a decompressed coordinate to one-previous coordinate value if a category of a line is not a straight line;determining, to be a coordinate value forming a contour, a result of adding a difference value of a decompressed coordinate to one-previous coordinate value if a category of a line is a straight line and if a difference value of decompressed coordinates is not “0”; andadding one-previous coordinate value to a value converted into a value before being subtracted by A by decompressing a difference value of coordinates stored next in order and determining the resultant value to be a coordinate value forming a contour if a category of a line is a straight line and if a difference value of decompressed coordinates is “0”.

7. An outline font compression method that compresses a difference of coordinate values stored adjacent to each other by means of a statistical coding system when reading out outline font data storing coordinate values necessary for drawing a contour of a character in order of drawing the contour in a clockwise or counterclockwise direction and also a category of a line connecting a pair of coordinates simultaneously, followed by compressing the coordinate values of the outline font data, making a first code table in the case of a category of a line connecting adjacent coordinates to each other being a straight line and a second code table in the case of a category of a line connecting adjacent coordinates to each other being the other than a straight line, and retaining these code tables in font data.

8. An outline font decompression method that obtains a coordinate value from data compressed by the outline font compression method according to the claim 7, determining, to be a coordinate value forming a contour, a value as a result of adding a difference value of coordinates decompressed by using said first code table to one-previous coordinate value if a category of a line is a straight line, anddetermining, to be a coordinate value forming a contour, a value as a result of adding a difference value of coordinates decompressed by using said second code table to one-previous coordinate value if a category of a line is not a straight line.