Image encoding/decoding apparatus

• US 5,600,374 A
• Filed: 09/02/1994
• Issued: 02/04/1997
• Est. Priority Date: 09/17/1993
• Status: Expired due to Term

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Shikakura, Akihiro
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/300,460
• Time in Patent Office: 886 Days
• Field of Search: 348/398, 348/423
• US Class Current: 375/240.11
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/1883 the unit relating to sub-band structure, e.g. hierarchical level, directional tree, e.g. low-high [LH], high-low [HL], high-high [HH]
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/645 by grouping of coefficients into blocks after the transform
• CPC Class Codes: H04N 19/65 using error resilience
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder

Abstract

An image encoding/decoding apparatus in which on the transmission side, image information is divided into at least two or more signal groups by a frequency band, the plurality of signal groups are individually high efficiency encoded, an error correction code is added to each of the plurality of encoded signal groups. The resultant signal groups are then multiplexed and transmitted. On the reception side, the transmitted multiplexed signal is divided into the signal groups for every frequency band divided on the transmission side, the error correction and the decoding of the high efficient encoded data are executed for every signal group, and the plurality of signal groups after decoding are frequency band synthesized, thereby reproducing the image information. At least two kinds of error correction codes of different error correcting abilities are used as error correction codes which are added to the plurality of signal groups on the transmission side.

Claims

1. An image encoding apparatus comprising:

a) input means for inputting an image signal;

b) dividing means for dividing the image signal input by said input means into signal groups of a plurality of frequency bands;

c) encoding means for encoding the plurality of signal groups divided by said dividing means; and

d) adding means for adding error correction check codes weighted in accordance with the frequency band to the image signal encoded by said encoding means.

2. An apparatus according to claim 1, wherein as an error correction check code to be added to the signal of a low frequency band among the signal groups divided every frequency band, said adding means adds the error correction check code of a correcting ability higher than that of the error correction check code that is added to the signal of a high frequency band.

3. An apparatus according to claim 1, wherein said encoding means executes a block encoding using an orthogonal transformation.

4. An apparatus according to claim 1, further having multiplexing means for multiplexing said plurality of encoded signal groups.

5. An apparatus according to claim 1, wherein said encoding means executes a compression encoding weighted in accordance with the frequency band.

6. An apparatus according to claim 4, wherein, in said encoding means, a compression ratio for the signal of a low frequency band among the signal groups divided every frequency band is set to be smaller than that for the signal of a high frequency band.

7. An image decoding apparatus comprising:

a) input means for inputting a plurality of encoded image signal groups, the plurality encoded image signal groups being formed by dividing an image signal into a plurality of signal groups of a plurality of frequency bands, encoding the plurality of divided signal groups and adding error correction check codes weighted according to the frequency bands to the plurality of encoded signal groups;

b) error code correcting means for correcting error codes of the plurality of encoded image signal groups by using the error correction check codes; and

c) decoding means for decoding the plurality of encoded image signal groups processed by said error code correcting means.

8. An apparatus according to claim 7, wherein an error correction check code added to the signal of a low frequency band among the image signal groups divided every frequency band has a correcting ability higher than that of the error correction check code added to the signal of a high frequency band.

9. An image encoding/decoding apparatus comprising:

a) input means for inputting an image signal;

b) dividing means for dividing the image signal input by said input means into signal groups of a plurality of frequency bands;

c) encoding means for encoding the plurality of signal groups divided by said dividing means;

d) adding means for adding error correction check codes weighted in accordance with the frequency band;

e) error code correcting means for correcting error codes in the encoded data of the plurality of encoded signal groups by using the error correction check codes; and

f) decoding means for decoding the encoded data of the plurality of encoded signal groups processed by said error code correcting means.

10. An apparatus according to claim 9, wherein as an error correction check code to be added to the signal of a low frequency band among the signal groups divided every frequency bands, said adding means adds the error correction check code of a correcting ability higher than that of the error correction check code which is added to the signal of a high frequency band.

11. An apparatus according to claim 9, wherein said encoding means executes a block encoding using an orthogonal transformation.

12. An apparatus according to claim 9, further having:

multiplexing means for multiplexing the encoded data of the plurality of signal groups encoded by said encoding means; and

dividing means for dividing the multiplexed encoded data into the plurality of signal groups.

13. An apparatus according to claim 9, wherein said encoding means executes a compression encoding weighted in accordance with the frequency band.

14. An apparatus according to claim 12, wherein a compression ratio for the signal of a low frequency band among the signal groups divided every frequency band in said encoding means is set to be smaller than that for the signal of a high frequency band.