Image processing method and apparatus

• US 5,841,904 A
• Filed: 01/23/1995
• Issued: 11/24/1998
• Est. Priority Date: 03/29/1991
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sugiura, Susumu
• Primary Examiner(s): Couso, Yon J.
• Application Number:
  US08/376,371
• Time in Patent Office: 1,401 Days
• Field of Search: 382/244, 382/245, 382/246, 382/248, 382/250, 382/251, 382/252, 382/240, 382/233, 382/253, 358/426, 358/261.2, 358/427
• US Class Current: 382/233
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform
• CPC Class Codes: H04N 1/64 Systems for the transmission or the storage of the colour picture signal; Details therefor, e.g. coding or decoding means therefor H04N19/00 takes precedence

Abstract

In coding color still image data into multi-valued image data, the image quality deteriorates when a large compression ratio is used. In the present invention, a transmitted image is classified using a parameter transmitted from the transmitting station, and the deterioration of image quality caused by compression at the transmitting station is estimated from the image classification. In an image reproduction, a quantization table is used in the case of an adaptive discrete cosine transform (ADCT) method to select an optimum neural network suitable for image reproduction and improve the image quality.

Claims

1. An image processing method comprising the steps of:

inputting coded image data and a coding parameter for use in processing the coded image data, wherein the coding parameter includes a quantizing parameter and is transmitted together with the coded image data;

decoding the coded image data to produce decoded image data in accordance with the coding parameter;

estimating a deterioration factor based on the coding parameter;

selecting a suitable correction parameter in accordance with the deterioration factor; and

correcting the decoded image data in accordance with the correction parameter.

2. A method according to claim 1, wherein the coded image data is data coded by an irreversible compression method.

3. A method according to claim 2, wherein the irreversible compression method quantizes image data.

4. A method according to claim 1, wherein, in said correcting step, the decoded image data is corrected by using a neural network.

5. A method according to claim 1, wherein the image data is color image data.

6. A method according to claim 1, wherein the coded image data is data coded by means of a DCT method.

8. A method according to claim 3, wherein the parameter is a parameter used in the quantization.

7. An image processing method comprising the steps of:

discriminating at a receiving station characteristics of coded image data transmitted from a transmitting station, including a deterioration factor of the coded image data, in accordance with a quantization table representing quantization characteristics or a Huffman coding table transmitted from the transmitting station, wherein the quantization table is transmitted together with the coded image data; and

determining an image correcting method to be used after the coded image data is decoded at the receiving station, in accordance with the discriminated characteristics,

wherein the image correcting method selects suitable correction parameters to correct the decoded image data.

10. A method according to claim 7, wherein the coded image data is data coded in accordance with the quantization table or the Huffman coding table.

11. A method according to claim 7, further comprising the step of performing image correction using a neural network.

12. A method according to claim 7, wherein the image data is color image data.

14. A method according to claim 7, wherein the coded image data is data coded by means of a DCT method.

9. An image processing apparatus comprising:

inputting means for inputting coded image data and a coding parameter for use in processing the coded image data, wherein the coding parameter includes a quantizing parameter and is transmitted together with the coded image data;

decoding means for decoding the coded image data to produce decoded image data in accordance with the coding parameter;

estimating means for estimating a deterioration factor based on the coding parameter;

selecting means for selecting a suitable correction parameter in accordance with the deterioration factor; and

correcting means for correcting the decoded image data in accordance with the correction parameter.

13. An apparatus according to claim 9, wherein the coded image data is coded according to a predetermined Huffman table.

15. An apparatus according to claim 13, wherein the coding parameter is the Huffman table.

16. A method according to claim 9, wherein the coded image data is data coded by an irreversible compression method.

17. An apparatus according to claim 9, further comprising means for reproducing the image data corrected by said correcting means, as a visual image.

18. An apparatus according to claim 17, wherein said reproducing means comprises a printer.

19. An apparatus according to claim 9, wherein said correcting means operates by using a neural network.

20. An apparatus according to claim 9, wherein the image data is color image data.

21. A method according to claim 9, wherein the coded image data is data coded by means of a DCT method.

22. An apparatus according to claim 9, wherein the coded image data is quantized according to a predetermined quantization table.

23. An apparatus according to claim 22, wherein the coding parameter is the quantization table.