Color image encoding method and apparatus

• US 5,909,505 A
• Filed: 03/04/1997
• Issued: 06/01/1999
• Est. Priority Date: 02/06/1990
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kato, Shigeo, Uchio, Hirokazu, Katayama, Akihiro, Yasuda, Yasuhiko
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US08/811,286
• Time in Patent Office: 819 Days
• Field of Search: 382/164, 382/176, 382/239, 382/244, 382/245, 382/246, 382/247, 382/163, 358/539, 358/530, 358/515, 358/462, 358/426, 358/427, 358/261.1, 358/261.2, 358/430
• US Class Current: 382/164
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: H04N 1/642 Adapting to different types of images, e.g. characters, graphs, black and white image portions
• CPC Class Codes: H04N 11/044 involving transform coding
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence

Abstract

This invention relates to an image processing apparatus having a function of encoding or decoding image data and discloses a technique for extracting an image feature, especially a thin image portion of a specific color of an image, and for encoding the thin image portion with high efficiency to minimize degradation of image quality by selecting an appropriate encoding method.

Claims

1. A color image encoding apparatus, comprising:

input means for inputting a color image;

separation means for separating out from the input image, a color character image and an image other than the color character image;

first encoding means for encoding the color character image using a first encoding method suitable for a color character;

second encoding means for encoding the image other than the color character image using a second encoding method different from the first encoding method; and

transmission means for transmitting encoded data encoded by said first and second encoding means.

2. An apparatus according to claim 1, wherein said first encoding means performs binary encoding.

3. An apparatus according to claim 2, wherein said first encoding means performs arithmetic encoding.

4. An apparatus according to claim 2, wherein said first encoding means performs MH (modified Huffman), MR (modified READ) or MMR (modified modified READ) encoding.

5. An apparatus according to claim 1, wherein said second encoding means performs multivalue encoding.

6. An apparatus according to claim 4, wherein said second encoding means performs orthogonal transformation encoding.

7. A color image encoding method, comprising:

an input step of inputting a color image;

a separation step of separating out from the input image, a color character image and an image other than the color character image;

a first encoding step of encoding the color character image using a first encoding method suitable for a color character;

a second encoding step of encoding the image other than the color character image using a second encoding method different from the first encoding method; and

a transmission step of transmitting encoded data encoded in said first and second encoding steps.

8. A color image encoding apparatus, comprising:

input means for inputting a color character image and an image other than the color character image, both images contained in a same color image;

first encoding means for encoding the color character image using a first encoding method suitable for a color character;

second encoding means for encoding the image other than the color character image using a second encoding method different from the first encoding method; and

transmission means for transmitting encoded data encoded by said first and second encoding means.

9. An apparatus according to claim 8, wherein said first encoding means performs binary encoding.

10. An apparatus according to claim 9, wherein said first encoding means performs arithmetic encoding.

11. An apparatus according to claim 9, wherein said first encoding means performs MH (modified Huffman), MR (modified READ) or MMR (modified modified READ) encoding.

12. An apparatus according to claim 8, wherein said second encoding means performs multivalue encoding.

13. An apparatus according to claim 12, wherein said second encoding means performs orthogonal transformation encoding.

14. A color image encoding method, comprising:

an input step of inputting a color character image and an image other than the color character image, both images contained in a same color image;

a first encoding step of encoding the color character image using a first encoding method suitable for a color character;

a second encoding step of encoding the image other than the color character image using a second encoding method different from the first encoding method; and

a transmission step of transmitting encoded data encoded in said first and second encoding steps.

15. A color image decoding apparatus, comprising:

input means for inputting a color character image and an image other than the color character image, the color character image being encoded using a first encoding method and the image other than the color character image being encoded using a second encoding method different from the first encoding method;

decoding means for decoding the color character image and the image other than the color character image; and

synthesizing means for synthesizing the decoded color character image and the decoded image other than the color character image.

16. An apparatus according to claim 15, wherein said first encoding means performs binary encoding.

17. An apparatus according to claim 16, wherein said first encoding means performs arithmetic encoding.

18. An apparatus according to claim 16, wherein said first encoding means performs MH (modified Huffman), MR (modified READ) or MMR (modified modified READ) encoding.

19. An apparatus according to claim 15, wherein said second encoding means performs multivalue encoding.

20. An apparatus according to claim 19, wherein said second encoding means performs orthogonal transformation encoding.

21. A color image decoding method, comprising:

an input step of inputting a color character image and an image other than the color character image, the color character image being encoded using a first encoding method and the image other than the color character image being encoded using a second encoding method different from the first encoding method;

a decoding step of decoding the color character image and the image other than the color character image; and

a synthesizing step of synthesizing the decoded color character image and the decoded image other than the color character image.