Image compression with tile alignment

• US 7,158,679 B2
• Filed: 05/29/2002
• Issued: 01/02/2007
• Est. Priority Date: 05/29/2001
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Sakuyama, Hiroyuki, Kodama, Taku, Sano, Yutaka
• Primary Examiner(s): Chen; Wenpeng
• Application Number:
  US10/156,093
• Publication Number:
  US 20020196970A1
• Time in Patent Office: 1,679 Days
• Field of Search: None
• US Class Current: 382/232
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform

Abstract

An image compression apparatus includes a tile size determiner, an image divider and an image compression processor. The tile size determiner determines an arbitrary size of a rectangular tile for each component of a still image having a plurality of components. The image divider divides the image using the rectangular tiles the sizes of which are determined by the tile size determiner. The image compression processor performs an irreversible compression process on the image divided by said image divider.

Claims

1. An image compression apparatus, comprising:

a tile size determiner that determines a size of a rectangular tile for each component of a still image having a plurality of components, said size being determined arbitrarily;

an image divider that divides the still image using the rectangular tiles, the sizes of said rectangular tiles being determined by said tile size determiner; and

an image compression processor that performs a compression process on the still image divided by said image divider,

wherein the tile size determiner includes a part that determines borders of the rectangular tiles for each of the components such that the borders do not overlap with a horizontal line and a vertical line included in the still image.

2. The image compression apparatus as claimed in claim 1, wherein the image compression processor includes a two-dimensional reversible discrete wavelet transformer, a quantization part and an entropy coder, and performs a compression process on the still image divided by the image divider.

3. An image decompression apparatus decompressing a compressed image compressed by the image compression apparatus as claimed in claim 1, comprising:

an image decompression processor that decompresses the compressed image based on information of the rectangular tiles included in the compressed image, the sizes of said rectangular tiles being determined by the tile size determiner.

4. The image decompression apparatus as claimed in claim 3, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and an inverse discrete cosine transformer.

5. The image decompression apparatus as claimed in claim 3, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and a two-dimensional reversible discrete wavelet inverse transformer.

6. An image compression apparatus, comprising:

a tile size determiner that determines a size of a rectangular tile for each component of a still image having a plurality of components, said size being determined arbitrarily;

an image divider that divides the still image using the rectangular tiles, the sizes of said rectangular tiles being determined by said tile size determiner; and

an image compression processor that performs a compression process on the still image divided by said image divider,

wherein the tile size determiner includes a part that determines borders of the rectangular tiles such that the borders of at least one of the components do not match a horizontal line and a vertical line included in the still image.

7. The image compression apparatus as claimed in claim 6, wherein the image compression processor includes a two-dimensional reversible discrete wavelet transformer, a quantization part and an entropy coder, and performs a compression process on the still image divided by the image divider.

8. The image decompression apparatus decompressing a compressed image compressed by the image compression apparatus as claimed in claim 6, comprising:

an image decompression processor that decompresses the compressed image based on information of the rectangular tiles included in the compressed image, the sizes of said rectangular tiles being determined by the tile size determiner.

9. The image decompression apparatus as claimed in claim 8, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and an inverse discrete cosine transformer.

10. The image decompression apparatus as claimed in claim 8, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and a two-dimensional reversible discrete wavelet inverse transformer.

11. An image compression apparatus, comprising:

a tile size determiner that determines a size of a rectangular tile for each component of a still image having a plurality of components, said size being determined arbitrarily;

an image divider that divides the still image using the rectangular tiles, the sizes of said rectangular tiles being determined by said tile size determiner; and

an image compression processor that performs a compression process on the still image divided by said image divider,

wherein the plurality of components include a R (red) component, a G (green) component and a B (blue) component, and the tile size determiner includes a part that determines borders of the rectangular tiles such that at least the borders of the rectangular tiles in the G component do not match a horizontal line and a vertical line included in the still image.

12. The image compression apparatus as claimed in claim 11, wherein the image compression processor includes a two-dimensional reversible discrete wavelet transformer, a quantization part and an entropy coder, and performs a compression process on the still image divided by the image divider.

13. The image decompression apparatus decompressing a compressed image compressed by the image compression apparatus as claimed in claim 11, comprising:

an image decompression processor that decompresses the compressed image based on information of the rectangular tiles included in the compressed image, the sizes of said rectangular tiles being determined by the tile size determiner.

14. The image decompression apparatus as claimed in claim 13, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and an inverse discrete cosine transformer.

15. The image decompression apparatus as claimed in claim 13, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and a two-dimensional reversible discrete wavelet inverse transformer.

16. An image compression apparatus, comprising:

a tile size determiner that determines a size of a rectangular tile for each component of a still image having a plurality of components, said size being determined arbitrarily;

an image divider that divides the still image using the rectangular tiles, the sizes of said rectangular tiles being determined by said tile size determiner; and

an image compression processor that performs an irreversible compression process on the still image divided by said image divider,

wherein the plurality of components include a Y component, a U component and a Y component, and the tile size determiner includes a part that determines borders of the rectangular tiles such that at least the borders of the rectangular tiles in the Y component do not match a horizontal line and a vertical line included in the still image.

17. The image compression apparatus as claimed in claim 16, wherein the image compression processor includes a two-dimensional reversible discrete wavelet transformer, a quantization part and an entropy coder, and performs a compression process on the still image divided by the image divider.

18. The image decompression apparatus decompressing a compressed image compressed by the image compression apparatus as claimed in claim 16, comprising:

an image decompression processor that decompresses the compressed image based on information of the rectangular tiles included in the compressed image, the sizes of said rectangular tiles being determined by the tile size determiner.

19. The image decompression apparatus as claimed in claim 18, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and an inverse discrete cosine transformer.

20. The image decompression apparatus as claimed in claim 18, wherein the image decompression processor includes an entropy decoder, a reverse quantization part and a two-dimensional reversible discrete wavelet inverse transformer.