CONVERSION TABLE COMPRESSION METHOD AND PROGRAM

Abstract

This invention relates to a conversion table compression method of compressing a conversion table and storing the conversion table in a storage medium, including an axial difference creating step of creating an axial difference table by calculating, from data stored in the conversion table, the difference values between grid points adjacent in predetermined directions along a plurality of axes which define the input space of the conversion table, a compressing step of compressing the axial difference table to create compressed data, and a storing step of storing the compressed data in a recording medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing a triaxial LUT;

FIG. 2 is a two-dimensionally exploded view of the triaxial LUT;

FIG. 3 is a view of exploding the triaxial LUT into a one-dimensional table;

FIG. 4 is a view of exploding a triaxial LUT, which stores a plurality of output data, into a one-dimensional table;

FIG. 5A is a main flowchart of the first embodiment;

FIG. 5B is a main flowchart of LUT compression procedures;

FIG. 6 is a flowchart of partial processing of conversion processing in the first embodiment;

FIG. 7 is a flowchart of partial processing of conversion processing in the first embodiment;

FIG. 8 is a flowchart of partial processing of conversion processing in the first embodiment;

FIG. 9 is a view showing change of the grid point value by differential processing;

FIG. 10 a main flowchart of the second embodiment;

FIG. 11 is a flowchart of partial processing of conversion processing in the second embodiment;

FIG. 12 is a flowchart of partial processing of conversion processing in the second embodiment;

FIG. 13 is a view showing a reduced LUT in the first stage in the second embodiment;

FIG. 14 is a view showing difference data in the first stage in the second embodiment;

FIG. 15 is a view showing a reduced LUT in the second stage in the second embodiment;

FIG. 16 is a view showing difference data in the second stage in the second embodiment;

FIG. 17 is a view showing a reduced LUT in the third stage in the second embodiment;

FIG. 18 is a view showing difference data in the third stage in the second embodiment;

FIG. 19 is a view showing data to be compressed in the second embodiment;

FIG. 20 is a view showing data to be compressed in the second embodiment;

FIG. 21 is a main flowchart of the first processing in the third embodiment;

FIG. 22 is a partial flowchart of the first processing in the third embodiment;

FIG. 23 is a partial flowchart of the first processing in the third embodiment;

FIG. 24 is a view showing an LUT management table in the first processing;

FIG. 25 is a view showing list A in the first processing;

FIG. 26 is a view of exploding the difference between triaxial LUTs into a one-dimensional table;

FIG. 27 is a view of exploding the difference between triaxial LUTs, which store a plurality of output data, into a one-dimensional table;

FIG. 28 is a main flowchart of the second processing in the third embodiment;

FIG. 29 is a partial flowchart of the second processing in the third embodiment;

FIG. 30 is a partial flowchart of the second processing in the third embodiment;

FIG. 31 is a partial flowchart of the second processing in the third embodiment;

FIG. 32 is a view showing an LUT management table in the second processing;

FIG. 33 is a view showing list A in the second processing;

FIG. 34 is a block diagram of a computer;

FIG. 35A is a main flowchart of LUT restore procedures in the first embodiment;

FIG. 35B is a main flowchart of LUT decoding procedures;

FIG. 36 is a partial flowchart of restore processing in the first embodiment;

FIG. 37 is a partial flowchart of restore processing in the first embodiment;

FIG. 38 is a partial flowchart of restore processing in the first embodiment;

FIG. 39 is a flowchart of restore processing in the second embodiment; and

FIG. 40 is a flowchart of restore processing in the third embodiment.

Claims

1. A conversion table compression method of compressing a conversion table and storing the conversion table in a storage medium, comprising: an axial difference creating step of creating an axial difference table by calculating, from data stored in the conversion table, difference values between grid points adjacent in predetermined directions along a plurality of axes which define an input parameter space of the conversion table;a compressing step of compressing the axial difference table to create compressed data; anda storing step of storing the compressed data in a recording medium.

2. A conversion table compression method of compressing a conversion table and storing the conversion table in a storage medium, comprising: a thinning-out step of thinning out, from a first conversion table, an element which forms the first conversion table, thereby creating a second conversion table;a hierarchic difference creating step of creating a hierarchic difference table corresponding to the thinned-out element by calculating a difference between a value of the element thinned out from the first conversion table in the thinning-out step, and an interpolation value obtained from the second conversion table in correspondence with the thinned-out element;a compressing step of compressing concatenated data obtained by concatenating the second conversion table to the hierarchic difference table, thereby creating compressed data; anda storing step of storing the compressed data in a recording medium.

3. The method according to claim 2, wherein the second conversion table created in the hierarchic difference creating step is regarded as the first conversion table to repeat the thinning-out step and the hierarchic difference creating step until the numbers of grid points along all axes which define an input parameter space of the conversion table become 2, andin the compressing step, a second conversion table obtained by the finally performed thinning-out step, and the hierarchic difference table obtained by the hierarchic difference creating step are compressed.

4. A conversion table compression method of compressing a conversion table and storing the conversion table in a storage medium, comprising: a table difference creating step of creating an inter-table difference table by calculating difference data between data stored in a first conversion table and data stored in a second conversion table identical in structure to the first conversion table;a compressing step of compressing the inter-table difference table to generate compressed data; anda storing step of storing, in a recording medium, the compressed data and information representing that the first conversion table is converted into the inter-table difference table between the first conversion table and the second conversion table.

5. A conversion table compression method of compressing a conversion table and storing the conversion table in a storage medium, comprising: an axial difference creating step of creating axial difference tables for a plurality of conversion tables by calculating, from data stored in the conversion tables, difference values between grid points adjacent in predetermined directions along a plurality of axes which define an input parameter space of the conversion table;a table difference creating step of creating an inter-table difference table by calculating difference data between data stored in a first axial difference table and data stored in a second axial difference table identical in structure to the first axial difference table among the axial difference tables created in the axial difference creating step;a compressing step of compressing the inter-table difference table to create compressed data; anda storing step of storing, in a recording medium, the compressed data and information representing that the first axial difference table is converted into difference data between the first axial difference table and a second axial difference table.

6. A conversion table compression method of compressing a conversion table and storing the conversion table in a storage medium, comprising: a thinning-out step of thinning out, from a first conversion table, an element which forms the first conversion table, thereby creating a second conversion table;a hierarchic difference creating step of creating a hierarchic difference table corresponding to the thinned-out element by calculating a difference between a value of the element thinned out from the first conversion table in the thinning-out step, and an interpolation value obtained from the second conversion table in correspondence with the thinned-out element;a concatenating step of creating concatenated data by concatenating the second conversion table to the hierarchic difference table;a table difference generating step of generating an inter-table difference table by calculating difference data between first concatenated data created in the concatenating step and second concatenated data identical in structure to the first concatenated data;a compressing step of compressing the inter-table difference table to generate compressed data; anda step of storing, in a recording medium, the compressed data and information representing that the first concatenated data is converted into the inter-table difference table between the first concatenated data and the second concatenated data.

7. The method according to claim 6, wherein the second conversion table created in the hierarchic difference creating step is regarded as the first conversion table to repeat the thinning-out step and the hierarchic difference creating step until the numbers of grid points along all axes which define an input parameter space of the conversion table become 2, andin the concatenating step, a second conversion table obtained by the finally performed thinning-out step, and the hierarchic difference table obtained by the hierarchic difference creating step are concatenated.

8. A conversion table compression method of compressing a conversion table and storing the conversion table in a storage medium, comprising: a thinning-out step of thinning out, from a first conversion table, an element which forms the first conversion table, thereby creating a second conversion table;a hierarchic difference creating step of creating a hierarchic difference table corresponding to the thinned-out element by calculating a difference between a value of the element thinned out from the first conversion table in the thinning-out step, and an interpolation value obtained from the second conversion table in correspondence with the thinned-out element;an axial difference creating step of creating an axial difference table by calculating, from data stored in the second conversion table, difference values between grid points adjacent in predetermined directions along a plurality of axes which define an input parameter space of the second conversion table;a step of concatenating the axial difference table and the hierarchic difference table into concatenated data;a compressing step of creating compressed data; anda storing step of storing the compressed data in a recording medium.

9. The method according to claim 8, wherein the second conversion table created in the hierarchic difference creating step is regarded as the first conversion table to repeat the thinning-out step and the hierarchic difference creating step until a data amount when concatenating and compressing an axial difference table of the second conversion table and the hierarchic difference table becomes larger than a data amount when compressing an axial difference table of the first conversion table, andin the concatenating step, a second conversion table obtained by the finally performed thinning-out step, and the hierarchic difference table obtained by the hierarchic difference creating step are concatenated.

10. The method according to claim 1, wherein an input parameter space of the conversion table is defined by three axes.

11. The method according to claim 1, wherein three axes which define an input parameter space of the conversion table have red, green, and blue luminance component values, and the conversion table has yellow, magenta, cyan, and black density component values in correspondence with the red, green, and blue luminance component values.

12. A recording medium which records compressed data obtained by compressing a conversion table by a conversion table compression method defined in claim 1.

13. A program which is recorded on a computer-readable recording medium and causes a computer to execute a method defined in claim 1.

14. A conversion table restoring method of restoring a conversion table which is compressed and stored in a storage medium by a computer, comprising: a decompressing step of reading compressed data from a recording medium and decoding the compressed data;a restoring step of restoring a conversion table from the data decoded in the decompressing step by adding values of grid points adjacent in predetermined directions along a plurality of axes which define an input parameter space of the conversion table; anda storing step of storing the conversion table restored in the restoring step in a storage medium.

15. A conversion table restoring method of restoring a conversion table which is compressed and stored in a storage medium by a computer, comprising: a decompressing step of reading compressed data from a recording medium and decoding the compressed data;a restoring step of restoring a conversion table by interpolating a thinned-out conversion table contained in the data decoded in the decompressing step, and adding an element of a hierarchic difference table contained in the decoded data to a corresponding element of the interpolated conversion table; anda storing step of storing the conversion table restored in the restoring step in a storage medium.

16. A conversion table restoring method of restoring a conversion table which is compressed and stored in a storage medium by a computer, comprising: a decompressing step of reading compressed data from a recording medium and decoding the compressed data;a restoring step of, when the data decoded in the decompressing step contains information representing that a first conversion table is converted into an inter-table difference table between the first conversion table and a second conversion table, restoring the first conversion table by adding an element of the second conversion table to a corresponding element of the inter-table difference table contained in the decompressed data; anda storing step of storing the conversion table restored in the restoring step in a storage medium.

17. A conversion table restoring method of restoring a conversion table which is compressed and stored in a storage medium by a computer, comprising: a decompressing step of reading compressed data from a recording medium and decoding the compressed data;a first restoring step of, when the data decoded in the decompressing step contains information representing that a first axial difference table for all axes is converted into an inter-table difference table between the first axial difference table for all axes and a second axial difference table for all axes, restoring the first axial difference table for all axes by adding an element of the second axial difference table for all axes to a corresponding element of the inter-table difference table contained in the decompressed data;a second restoring step of restoring a first conversion table for the first axial difference table for all axes decoded in the first restoring step by adding values of grid points adjacent in predetermined directions along a plurality of axes which define an input parameter space of the conversion table; anda storing step of storing the first conversion table restored in the restoring step in a storage medium.