Claims
- 1 A method for compressing blocks of pixels comprising:
generating original pixels grouped into blocks of pixels, generating an image format signal associated with each block of pixels, the image format signal indicating whether there is one type of image format data within the block of pixels or whether the block of pixels contains a boundary between two types of image format data, selecting in response to the image format signal one of two compressors to use, one compressor being optimized for compression of a block of pixels containing a boundary between two types of image format data, and compressing the block of pixels using the selected compressor to yield a compressed block signal.
- 2. A method for compressing blocks of pixels according to claim 1 wherein at least one of the compressors uses hierarchical vector quantization.
- 3. A method for compressing blocks of pixels according to claim 1 wherein one of the types of image data comprises halftone image data.
- 4. A method for compressing blocks of pixels according to claim 1 wherein one of the types of image data comprises contone image data.
- 5. A method for compressing blocks of pixels according to claim 1 wherein one of the types of image format data comprises text image data.
- 6. A method for compressing blocks of pixels according to claim 1 wherein one of the types of image format data comprises graphic image format data.
- 7. A method for compressing blocks of pixels according further comprising generating an error signal.
- 8. Apparatus for compressing blocks of pixels, comprising:
a pixel block generator, said pixel block generator producing a pixel block signal and an image format data signal associated therewith which is indicative of the type of image format data contained in the block of pixels, a plurality of look-up tables, each table being optimized for compression of a particular of image format data, one of said tables being optimized for compression of a block of pixels containing more than one type of image format data, a look-up table selector responsive to the image format data signal to select one of the look-up tables, and a compressor using the selected look-up table and the pixel block signal to generate a code word indicative of at least a pair of pixels in the block of pixels.
- 9. Apparatus for compressing a block of pixels according to claim 8 wherein one of the look-up tables is optimized for compression of pixels containing text image format data.
- 10. Apparatus for compressing a block of pixels according to claim 8 wherein one of the look-up tables is optimized for compression of pixels containing halftone data.
- 11. Apparatus for compressing a block of pixels according to claim 8 wherein one of the look-up tables is optimized for compression of pixels containing contone data.
- 12. Apparatus for compressing a block of pixels according to claim 8 wherein one of the look-up tables is optimized for compression of pixels containing graphics image format data.
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is a continuation of copending U.S. application Ser. No. 09/106,732, filed Jun. 29, 1998, the contents of which are incorporated herein by reference.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09106732 |
Jun 1998 |
US |
Child |
10123786 |
Apr 2002 |
US |