Apparatus and method for selecting encoding schemes based upon image content

• US 6,215,904 B1
• Filed: 11/30/1994
• Issued: 04/10/2001
• Est. Priority Date: 11/30/1994
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Lavallee, Pierre A.
• Primary Examiner(s): Au, Amelia
• Assistant Examiner(s): Johnson, Timothy M.
• Application Number:
  US08/351,102
• Time in Patent Office: 2,323 Days
• Field of Search: 382/234, 382/239, 382/180, 382/282, 382/176, 382/177, 382/306, 358/453, 358/462, 358/467
• US Class Current: 382/234
• 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 1/41 Bandwidth or redundancy reduction by scanning H04N1/17 ; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00

Abstract

An image scanner apparatus scans a document and provides image data in digital form representing the scanned document. The compression apparatus detects characteristics of the image data and compresses the image data using parallel compressors, each employing a different encoding scheme. The apparatus then selects compressed image data encoded by one of the compressors in accordance with the detected characteristics and stores the selected data.

Claims

1. An image compression apparatus comprising:

means for generating a first set of control signals indicating whether image data contains pictorial image data or text image data based upon image characteristics;

first encoding means for encoding the image data in accordance with a first encoding scheme optimized for pictorial image data;

second encoding means for encoding the image data in accordance with a second encoding scheme optimized for text image data, as the first encoding means encodes the image data; and

control means for receiving encoded image data from both the first encoding means and the second encoding means and for selecting encoded image data from one of the first and second encoding means based upon the first set of control signals.

2. The image compression apparatus according to claim 1, wherein the first and second encoding means are arranged in parallel with respect to each other.

3. The image compression apparatus according to claim 1, wherein the generating means includes means for determining that the image data contains pictorial data.

4. The image compression apparatus according to claim 1, wherein the generating means includes means for determining that the image data contains text data.

5. The image compression apparatus according to claim 1, further comprising means for obtaining image data.

6. The image compression apparatus according to claim 5, wherein the obtaining means includes a scanner.

7. The image compression apparatus according to claim 1, further comprising means for selectively storing encoded image data from one of the first and second encoding means in accordance with user selected information.

8. The image compression apparatus according to claim 1, wherein the pictorial image data includes at least one of continuous and halftone image data.

13. The apparatus according to claim 1, wherein the control means comprises means for receiving a second set of control signals and for selecting encoded image data from one of the first and second encoding means based upon the first and second sets of control signals.

14. The apparatus according to claim 13, wherein the second set of control signals represents the selection of a user selection mode.

15. The apparatus according to claim 13, wherein the second set of control signals represents the selection of an auto line mode.

16. The apparatus according to claim 13, wherein the second set of control signals represents the selection of an auto area mode.

9. A method of data compression, comprising the steps of:

receiving image data;

detecting image characteristics in the received image data;

generating a first set of control signals indicating whether the received image data contains pictorial image data or text image data based upon the detected image characteristics;

compressing the received image data using a first compressor;

compressing the received image data using a second compressor, as the first compressor compresses the received image data;

receiving compressed image data from both the first compressor and the second compressor;

selecting compressed image data from one of the first and second compressors based upon the first set of control signals; and

storing the selected image data in memory.

10. The method of data compression according to claim 9, further comprising the step of:

storing a tag associated with the stored image data indicating a method in which the stored image data was compressed.

11. The method data compression according to claim 10, further comprising the steps of:

reading the compressed image data and associated tag from memory; and

decompressing the read image data using a decompression method corresponding to the associated tag.

12. The method of data compression according to claim 9, wherein the step of detecting image characteristics includes determining whether received image data includes at least one of pictorial data and text data.

17. The method according to claim 9, further comprising the step of receiving a second set of control signals, and wherein the step of selecting compressed image data comprises the substep of selecting compressed image data from one of the first and second compressors based upon the first and second sets of control signals.

18. The apparatus according to claim 17, wherein the second set of control signals represents the selection of a user selection mode.

19. The apparatus according to claim 17, wherein the second set of control signals represents the selection of an auto line mode.

20. The apparatus according to claim 17, wherein the second set of control signals represents the selection of an auto area mode.