IMAGE PROCESSING APPARATUS, CONTROL METHOD, AND COMPUTER-READABLE MEDIUM

• US 20110317232A1
• Filed: 06/13/2011
• Published: 12/29/2011
• Est. Priority Date: 06/24/2010
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Aoyagi, Takeshi
• Granted Patent: US 8,570,627 B2
• Time in Patent Office: Days
• US Class Current: 358/518
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression

Abstract

An image processing apparatus comprises: an unit configured to compress image data based on values of pixels and a layout of the pixels for each tile including the predetermined number of pixels; an unit configured to calculate a representative value from the values of the pixels included in the tile; an unit configured to determine based on a distribution of the representative values of tiles included in a first area including the first number of tiles whether or not a tile of interest included in the first area is to be corrected; an unit configured to calculate a correction value for the tile of interest based on the representative values of tiles included in a second area including the second number of tiles; and an unit configured to add representative values of the tiles, determination results of the tiles, and the correction value to the image data compressed.

Claims

1. An image processing apparatus, which applies correction processing to input image data, comprising:

a compression unit configured to compress the image data based on values of pixels and a layout of the pixels for each tile including the predetermined number of pixels;

a representative value calculation unit configured to calculate a representative value from the values of the pixels included in the tile;

a determination unit configured to determine based on a distribution of the representative values of tiles included in a first area including the first number of tiles whether or not a tile of interest included in the first area is to be corrected;

a correction value calculation unit configured to calculate a correction value for the tile of interest based on the representative values of tiles included in a second area including the second number of tiles; and

an addition unit configured to add representative values of the tiles, determination results of the tiles by said determination unit, and the correction value to the image data compressed by said compression unit.

2. The apparatus according to claim 1, further comprising an expansion unit configured to expand the compressed image data,

wherein said expansion unit corrects the image data when said expansion unit expands the compressed image data using the representative values, the determination results by said determination unit, and the correction value, which are added to the compressed image data by said addition unit.

3. The apparatus according to claim 1, wherein said representative value calculation unit calculates, as the representative value, an average value of the values of the pixels included in the tile.

4. The apparatus according to claim 1, wherein said representative value calculation unit selects, as the representative value, a mode value from the values of the pixels included in the tile.

5. The apparatus according to claim 1, wherein when the distribution of the representative values of the tiles included in the first area falls within a predetermined range, said determination unit determines that the tile of interest is to be corrected.

6. The apparatus according to claim 1, further comprising a region determination unit configured to determine a gradation region in the input image data,

wherein when the tile of interest is included in the gradation region, said determination unit determines that the tile of interest is not to be corrected.

7. The apparatus according to claim 6, wherein when representative values of tiles included in a region to be determined are always increasing, are always decreasing, or are constant in both a main scan direction and a sub-scan direction, said region determination unit determines that the region is the gradation region.

8. The apparatus according to claim 1, wherein the first area to be determined by said determination unit and the second area used in calculations of said correction value calculation unit are areas having the same range.

9. The apparatus according to claim 1, wherein the first area to be determined by said determination unit and the second area used in calculations of said correction value calculation unit are areas having different ranges.

10. The apparatus according to claim 1, wherein said correction value calculation unit calculates, as the correction value, an average value of representative values of tiles included in the second area.

11. The apparatus according to claim 1, wherein said correction value calculation unit calculates, as the correction value, a mode value of representative values of tiles included in the second area.

12. The apparatus according to claim 2, further comprising a receiving unit configured to receive the correction value,

wherein said expansion unit executes expansion processing using the correction value received by said receiving unit in place of the correction value calculated by said correction value calculation unit.

13. The apparatus according to claim 1, wherein the input image data is color image data,

said representative value calculation unit calculates representative values of respective color attributes from the values of the pixels included in the tile, and

said correction value calculation unit calculates correction values for the respective color attributes in the tile of interest.

14. The apparatus according to claim 1, wherein the predetermined number of pixels which configure the tile is configured by 32×

32 pixels.

15. A control method of an image processing apparatus, which applies correction processing to input image data, comprising:

a compression step of controlling a compression unit to compress the image data based on values of pixels and a layout of the pixels for each tile including the predetermined number of pixels;

a representative value calculation step of controlling a representative value calculation unit to calculate a representative value from the values of the pixels included in the tile;

a determination step of controlling a determination unit to determine based on a distribution of the representative values of tiles included in a first area including the first number of tiles whether or not a tile of interest included in the first area is to be corrected;

a correction value calculation step of controlling a correction value calculation unit to calculate a correction value for the tile of interest based on the representative values of tiles included in a second area including the second number of tiles; and

an addition step of controlling an addition unit to add representative values of the tiles, determination results of the tiles by the determination unit, and the correction value to the image data compressed in the compression step.

16. A computer-readable medium storing a program for controlling a computer to function as:

a compression unit configured to compress image data based on values of pixels and a layout of the pixels for each tile including the predetermined number of pixels;

a representative value calculation unit configured to calculate a representative value from the values of the pixels included in the tile;

a determination unit configured to determine based on a distribution of the representative values of tiles included in a first area including the first number of tiles whether or not a tile of interest included in the first area is to be corrected;

a correction value calculation unit configured to calculate a correction value for the tile of interest based on the representative values of tiles included in a second area including the second number of tiles; and

an addition unit configured to add representative values of the tiles, determination results of the tiles by said determination unit, and the correction value to the image data compressed by said compression unit.