Image compression device, image decompression device, image compression/decompression device, program for executing on a computer to perform functions of such devices, and recording medium storing such a program

• US 20030202581A1
• Filed: 03/14/2003
• Published: 10/30/2003
• Est. Priority Date: 03/15/2002
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Kodama, Taku
• Granted Patent: US 7,352,908 B2
• Time in Patent Office: Days
• US Class Current: 375/240.03
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/127 Prioritisation of hardware or computational resources
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/649 the transform being applied to non rectangular image segments

Abstract

An image compression device comprising an image division unit dividing an image into a plurality of regions, a region designation unit designating a region of interest in the image, a quantization rate determination unit determining quantization rate with respect to each region divided by the image division unit, and a compression control unit controlling compression with respect to each region based on the quantization rate determined by the quantization rate determination unit is disclosed. In the image compression device, the quantization rate determination unit can determine quantization rate for the region of interest different from the quantization rate for the regions other than the region of interest.

Claims

1. An image compression device comprising:

an image division unit to divide an image into a plurality of regions;

a region designation unit to desigate a region of interest in the image;

a quantization rate determination unit to determine a quantization rate with respect to each of the regions divided by the image division unit; and

a compression control unit to control compression with respect to each of the regions based on the quantization rate determined by the quantization rate determination unit, wherein the quantization rate determination unit is operable to determine the quantization rate for the region of interest different from the quantization rate for the regions other than the region of interest.

2. The image compression device as claimed in claim 1, further comprising:

a level of interest determination unit to determine a level of interest for the region of interest designated by the region designation unit, wherein the quantization rate determination unit determines a different quantization rate according to the level of interest determined for the region of interest by the level of interest determination unit.

3. The image compression device as claimed in claim 1, wherein the image division unit applies two or more from a group consisting of a tile, a precinct, a code block, and a pixel, in combination, to divide the image into the plurality of regions.

4. The image compression device as claimed in claim 1, wherein the image division unit applies a region determined according to an area of interest in the image to divide the image into the plurality of regions.

5. The image compression device as claimed in claim 1, wherein a boundary of the regions divided by the image division unit is a boundary of two or more from a group consisting of a tile boundary, a precinct boundary, and a code block boundary.

6. The image compression device as claimed in claim 1, further comprising:

a two-dimensional wavelet transformation unit,

a quantization unit coupled to the two-dimensional wavelet transformation unit, and

an entropy coding unit coupled to the quantization unit.

7. An image compression device comprising:

an image division unit to divide an image into a plurality of regions;

a region designation unit to designate a region of interest in the image;

a bit number determination unit to control the number of bits, which are available when quantization is made, with respect to each of the regions divided by the image division unit; and

a compression control unit to control compression with respect to each of the regions based on the number of bits determined by the bit number determination unit;

wherein the bit number determination is operable to determine the number of bits for the region of interest different from the number of bits for the regions other than the region of interest.

8. The image compression device as claimed in claim 7, further comprising a level of interest determination unit to determine a level of interest for the region of interest designated by the region designation unit, wherein the bit number determination unit determines a different number of bits according to the level of interest determined for the region of interest by the level of interest determination unit.

9. The image compression device as claimed in claim 7, wherein the image division unit applies two or more from a unit group consisting of a tile, a precinct, a code block, and a pixel, in combination, to divide the image into the plurality of regions.

10. The image compression device as claimed in claim 7, wherein the image division unit applies a region determined according to an area of interest in the image to divide the image into the plurality of regions.

11. The image compression device as claimed in claim 7, wherein a boundary of the regions divided by the image division unit is a boundary of two or more from a group consisting of a tile boundary, a precinct boundary, and a code block boundary.

12. The image compression device as claimed in claim 7, wherein the image compression device comprises:

a two-dimensional wavelet transformation unit,

a quantization unit coupled to the two-dimensional tranformation unit; and

an entropy coding unit coupled to the quantization unit.

13. An image compression device comprising:

an image division unit to divide an image into a plurality of regions;

a region designation unit to designate a region of interest in the image;

a bit plane allocation unit to allocate one or a plurality of bit planes to a layer with respect to each of the regions divided by the image division unit; and

a compression control unit to control compression with respect to each of the regions based on the layer allocated with one or a plurality of bit planes, wherein the bit plane allocation unit is operable to allocate the number of bit planes to the layer for the region of interest different from the number of bit planes to the layer for the regions other than the region of interest.

14. The image compression device as claimed in claim 13, further comprising:

a level of interest determination unit to determine a level of interest for the region of interest designated by the region designation unit, wherein bit plane allocation unit allocates a different number of bit planes to the layer according to the level of interest determined for the region of interest by the mid level of interest determination unit.

15. The image compression device as claimed in claim 13, wherein image division unit applies two or more from a unit group consisting of a tile, a precinct, a code block, and a pixel, in combination, to divide the image into the plurality of regions.

16. The image compression device as claimed in claim 13, wherein image division unit applies a region determined according to an area of interest in the image to divide the image into the plurality of regions.

17. The image compression device as claimed in claim 13, wherein a boundary of the regions divided by the image division unit is a boundary of two or more from a group consisting of a tile boundary, a precinct boundary, and a code block boundary.

18. The image compression device as claimed in claim 13, wherein the image compression device comprises:

a two-dimensional wavelet transformation unit;

a quantization unit coupled to the two-dimensional wavelet transformation unit; and

an entropy coding unit coupled to the quantization unit.

19. An image compression device comprising:

an image division unit to divide an image into a plurality of regions;

a resolution determination unit to determine the resolution with respect to each of the regions divided by the image division unit; and

a compression control unit to control compression with respect to each of the regions based on the resolution determined for each of the regions by the resolution determination unit.

20. The image compression device as claimed in claim 19, wherein the image division unit applies more than two from a group consisting of a tile, a precinct, a code block, and a pixel, in combination, to divide the image into the plurality of regions.

21. The image compression device as claimed in claim 19, wherein the image division unit applies a region determined according to an area of interest in the image to divide the image into the plurality of regions.

22. The image compression device as claimed in claim 19, wherein a boundary of the regions divided by the image division unit is a boundary of two or more from a group consisting of a tile boundary, a precinct boundary, and a code block boundary.

23. The image compression device as claimed in claim 19, wherein image compression device comprises:

a two-dimensional wavelet transformation unit;

a quantization unit coupled to the two-dimensional wavelet transformation unit; and

an entropy coding unit coupled to the quantization unit.

24. An image compression device comprising:

an image division unit to divide an image into a plurality of regions;

a bit plane decomposition unit to decompose each of the plurality of regions divided by the image division unit into bit planes;

a level of interest determination unit to determine a level of interest for the decomposed bit planes; and

a compression control unit to control compression with respect to each of the regions based on the level of interest determined for the decomposed bit planes by the level of interest determination unit wherein a compressed image is generated according to the level of interest determined for the decomposed bit planes.

25. An image compression device comprising:

an image division unit to divide an image into a plurality of regions;

a bit plane decomposition unit to decompose each of the plurality of regions divided by the image division unit into bit planes;

a level of interest determination unit to determine a level of interest for the decomposed bit planes;

a compression control unit to control compression with respect to each of the regions based on the level of interest determined for the decomposed bit planes by the said level of interest determination unit; and

a tag processing control unit to control tag processing based on the level of interest determined for the decomposed bit planes, wherein a compressed image is generated according to the level of interest determined for the decomposed bit planes.

26. An image decompression device for decompressing an image compressed by an image compression device, wherein the image compression device comprises

an image division unit to divide an image into a plurality of regions,

a region designation unit to designate a region of interest in the image,

a quantization rate determination unit to determine a quantization rate with respect to each of the regions divided by the image division unit, and

a compression control unit to control compression with respect to each of the regions based on the quantization rate determined by the quantization rate determination unit, wherein the quantization rate determination unit is operable to determine the quantization rate for the region of interest different from the quantization rate for the regions other than the region of interest, and further wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information is contained in the compressed image.

27. The image decompression device as claimed in claim 26, wherein the image decompression device comprises:

a two-dimension inverse wavelet transformation unit;

an inverse quantization unit coupled to the two-dimensional wavelet transformation unit; and

an entropy decoding unit coupled to the quantization unit.

28. An image decompression device for decompressing an image compressed by an image compression device, wherein the image compression device comprises

an image division unit to divide an image into a plurality of regions,

a region designation unit to designate a region of interest in the image,

a bit number determination unit to determine the number of bits, which are available when quantization is made, with respect to each of the regions divided by the image division unit, and

a compression control unit to control compression with respect to each of the regions based on the number of bits determined by the bit number determination unit, wherein the bit number determination unit is operable to determine the number of bits for the region of interest different from the number of bits for the regions other than the region of interest, wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information is contained in the compressed image.

29. The image decompression device as claimed in claim 28, wherein the image decompression device comprises:

a two-dimension inverse wavelet transformation unit;

an inverse quantization unit coupled to the two-dimensional wavelet transformation unit; and

an entropy decoding unit coupled to the quantization unit.

30. An image decompression device for decompressing an image compressed by an image compression device, wherein the image compression device comprises

an image division unit to divide an image into a plurality of regions,

a region designation unit to designate a region of interest in the image,

a bit plane allocation unit to allocate one or a plurality of bit planes to a layer with respect to each of the regions divided by the image division unit, and

a compression control unit to control compression with respect to each of the regions based on the layer allocated with one or a plurality of bit planes, wherein the bit plane allocation unit is operable to allocate the number of bit planes to the layer for the region of interest different from the number of bit planes to the layer for the regions other than the region of interest, and wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information is contained in the compressed image.

31. The image decompression device as claimed in claim 30, wherein said image decompression device comprises:

a two-dimension inverse wavelet transformation unit;

an inverse quantization unit coupled to the two-dimensional wavelet transformation unit; and

an entropy decoding unit coupled to the quantization unit.

32. An image decompression device for decompressing an image compressed by an image compression device, wherein the image compression device comprises an image division unit to divide an image into a plurality of regions,;

a resolution determination unit to determine the resolution with respect to each of the regions divided by the image division unit; and

a compression control unit to control compression with respect to each of the regions based on the resolution determined for each of the regions by the resolution determination unit, wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information contained in the compressed image.

33. The image decompression device as claimed in claim 32, wherein image decompression device comprises:

a two-dimension inverse wavelet transformation unit;

an inverse quantization unit coupled to the two-dimensional wavelet transformation unit, and

an entropy decoding unit coupled to the quantization unit.

34. An image compression/decompression device comprising:

an image compression device comprising

an image division unit to divide an image into a plurality of regions,

a region designation unit to designate a region of interest in the image,

a quantization rate determination unit to determine a quantization rate with respect to each of the regions divided by the image division unit, and

a compression control unit to control compression with respect to each of the regions based on the quantization rate determined by the quantization rate determination unit, wherein the quantization rate determination unit is operable to determine the quantization rate for the region of interest different from the quantization rate for the regions other than the region of interest; and

an image decompression device to decompress an image compressed by an image compression device, wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information is contained in the compressed image, and further wherein functions of the image compression device and the image decompression device are realized by a combination of a two-dimensional wavelet transformation/inverse transformation unit, a quantization/inverse quantization unit, and an entropy coding/decoding unit.

35. An image compression/decompression device comprising:

an image compression device comprising

an image division unit to divide an image into a plurality of regions,

a region designation unit to designate a region of interest in the image,

a bit number determination unit to determine the number of bits, which are available when quantization is made, with respect to each of the regions divided by the image division unit, and

a compression control unit to control compression with respect to each of the regions based on the number of bits determined by the bit number determination unit, wherein the bit number determination unit is operable to determine the number of bits for the region of interest different from the number of bits for the regions other than the region of interest; and

an image decompression device to decompress an image compressed by an image compression device, wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information is contained in the compressed image, and further wherein functions of the image compression device and the image decompression device are realized by a combination of a two-dimensional wavelet transformation/inverse transformation unit, a quantization/inverse quantization unit, and an entropy coding/decoding unit.

36. An image compression/decompression device comprising:

an image compression device comprising

an image division unit to divide an image into a plurality of regions,

a region designation unit to designate a region of interest in the image,

a bit plane allocation unit to allocate one or a plurality of bit planes to a layer with respect to each of the regions divided by the image division unit, and

a compression control unit to control compression with respect to each of the regions based on the layer allocated with one or a plurality of bit planes, wherein the bit plane allocation unit is operable to allocate the number of bit planes to the layer for the region of interest different from the number of bit planes to the layer for the regions other than the region of interest; and

an image decompression device to decompress an image compressed by the image compression device, wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information is contained in the compressed image, and further wherein functions of the image compression device and the image decompression device are realized by a combination of a two-dimensional wavelet transformation/inverse transformation unit, a quantization/inverse quantization unit, and an entropy coding/decoding unit.

37. An image compression/decompression device comprising:

an image compression device comprises

an image division unit to divide an image into a plurality of regions,

a resolution determination unit to determine the resolution with respect to each of the regions divided by the image division unit, and

a compression control unit to control compression with respect to each of the regions based on the resolution determined for each of the regions by the resolution determination unit; and

an image decompression device to decompress an image compressed by the image compression device, wherein the compressed image is decompressed based on information of each of the regions divided by the image division unit, which information contained in the compressed image, and further wherein functions of the image compression device and the image decompression device are realized by a combination of a two-dimensional wavelet transformation/inverse transformation unit, a quantization/inverse quantization unit, and an entropy coding/decoding unit.

38. A method comprising:

dividing an image into a plurality of regions;

designating a region of interest in the image;

determining a quantization rate with respect to each of the regions, where the quantization rate for the region of interest is different from the quantization rate for the regions other than the region of interest; and

controlling compression with respect to each of the regions based on the quantization rate.

39. A method comprising:

dividing an image into a plurality of regions;

designating a region of interest in the image;

determining the number of bits that are available when quantization is made, with respect to each of the regions, where the number of bits for the region of interest is different from the number of bits for the regions other than the region of interest; and

controlling compression with respect to each of the regions based on the number of bits.

40. A method comprising:

dividing an image into a plurality of regions;

designating a region of interest in the image;

allocating one or a plurality of bit planes to a layer with respect to each of the regions, wherein the number of bit planes to the layer for the region of interest is different from the number of bit planes to the layer for the regions other than the region of interest; and

controlling compression with respect to each of the regions based on the layer allocated with one or a plurality of bit planes.

41. A method comprising:

dividing an image into a plurality of regions;

determining the resolution with respect to each of the regions; and

controlling compression with respect to each of the regions based on the resolution determined for each of the regions.

42. An article of manufacture having one or more computer readable recording media which, when executed by a system, causes the system to:

divide an image into a plurality of regions;

designate a region of interest in the image;

determine a quantization rate with respect to each of the regions, where the quantization rate for the region of interest is different from the quantization rate for the regions other than the region of interest; and

control compression with respect to each of the regions based on the quantization rate.

43. An article of manufacture having one or more computer readable recording media which, when executed by a system, causes the system to:

divide an image into a plurality of regions;

designate a region of interest in the image;

determine the number of bits that are available when quantization is made, with respect to each of the regions, where the number of bits for the region of interest is different from the number of bits for the regions other than the region of interest; and

control compression with respect to each of the regions based on the number of bits.

44. An article of manufacture having one or more computer readable recording media which, when executed by a system, causes the system to:

divide an image into a plurality of regions;

designate a region of interest in the image;

allocate one or a plurality of bit planes to a layer with respect to each of the regions, wherein the number of bit planes to the layer for the region of interest is different from the number of bit planes to the layer for the regions other than the region of interest; and

control compression with respect to each of the regions based on the layer allocated with one or a plurality of bit planes.

45. A computer readable recording medium which, when executed by a system, causes the system to:

divide an image into a plurality of regions;

determine the resolution with respect to each of the regions; and

control compression with respect to each of the regions based on the resolution predetermined for each of the regions.