Fast method for fax encoded data conversion

• US 6,950,213 B1
• Filed: 12/20/2000
• Issued: 09/27/2005
• Est. Priority Date: 12/20/2000
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Systems, Inc.
• Inventors: Gurevich, Vladimir Alexandrovich
• Primary Examiner(s): Williams, Kimberly
• Assistant Examiner(s): Worku, Negussie
• Application Number:
  US09/742,552
• Time in Patent Office: 1,742 Days
• Field of Search: 358/401, 358/539, 358/426.07, 358/426.04, 358/426.16, 358/426.13, 358/407, 358/1.15, 358/442, 382/232, 382/245, 382/233, 382/176, 379/100.09
• US Class Current: 358/401
• CPC Class Codes: H04N 1/33323 transmission mode only, e.g. speed
• 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
• CPC Class Codes: H04N 2201/33357 Compression mode

Abstract

In accordance with an embodiment of the present invention, a fax decoding/re-encoding system for transferring fax images between a sending fax machine and a receiving fax machine includes a decoder responsive to an encoded fax image defined by rows of scan lines. The decoder decodes the scan lines of the encoded fax image and generates run-length representation of the encoded fax image. A scanline manipulation device is responsive to the run-length representation for manipulating the same and generating a manipulated fax image without generating a bitmap of the encoded fax image. The fax decoding/re-encoding system further including a re-encoder responsive to said manipulated fax image and adaptive to generate a re-encoded fax image that is substantially the same as the encoded fax image, wherein the fax decoding/re-encoding system avoids the need for a bitmap for generating a re-encoded fax image thereby substantially reducing re-encoding time.

Claims

1. A fax decoding/re-encoding system for transferring fax images between a sending fax machine and a receiving fax machine comprising:

a decoder responsive to an encoded fax image defined by rows of scan lines, said decoder for decoding the scan lines of the encoded fax image and generating run-length representation of said encoded fax image;

a scanline manipulation device responsive to said run-length representation for manipulating the same and generating a manipulated fax image without generating a bitmap of the encoded fax image; and

a re-encoder responsive to said manipulated fax image and adaptive to generate a re-encoded fax image that is substantially the same as the encoded fax image.

2. A fax decoding/re-encoding system as recited in claim 1 wherein Group 3 is used for transmission of fax images between the sending fax machine and the receiving fax machine.

3. A fax decoding/re-encoding system as recited in claim 1 wherein the decoder, scanline manipulator and re-encoder are part of an access server.

4. A fax decoding/re-encoding system as recited in claim 1 wherein the decoder further includes a one-dimensional decoder and a one-dimensional run-length representation block coupled to the one-dimensional decoder, said one-dimensional decoder responsive to the encoded fax image and for one-dimensional decoding of at least one of the scan lines of the encoded fax image and said one-dimensional run-length representation block for providing a one-dimensional run-length representation of the decoded fax image to the scan line manipulation device.

5. A fax decoding/re-encoding system as recited in claim 4 wherein the decoder further includes a two-dimensional decoder responsive to the encoded fax image for two-dimensional decoding of the same.

6. A fax decoding/re-encoding system as recited in claim 5 wherein the decoder further includes a two-dimensional run-length representation block for providing a two-dimensional run-length representation of the decoded fax image to the scan line manipulation device.

7. A fax decoding/re-encoding system as recited in claim 6 wherein the decoder further includes a reference line buffer responsive to the decoded scan lines wherein each of the decoded scan lines is stored within the buffer and used to compare the stored scan line, a reference scan line, to the encoded fax image scan line for two-dimensional decoding.

8. A fax decoding/re-encoding system as recited in claim 1 wherein said re-encoder includes a one-dimensional re-encoder for one-dimensionally re-encoding the manipulated fax image and a two-dimensional re-encoder for two-dimensional re-encoding the manipulated fax image wherein the one-dimensional or two-dimensional re-encoding are selectively employed depending upon the decoding technique being employed.

9. A fax decoding/re-encoding system as recited in claim 1 wherein said decoder includes a one-dimensional decoder responsive to said scan lines of said encoded fax image for one-dimensionally decoding said scan lines and wherein said decoder further includes a two-dimensional decoder responsive to said scan lines of said encoded fax image for two-dimensionally decoding the scan lines wherein said decoder selectively decodes the encoded fax image using either the one-dimensional decoder or the two-dimensional decoder.

10. A fax decoding/re-encoding system as recited in claim 9 wherein a first scan line of the encoded fax image is decoded using the one-dimensional decoder regardless of whether the one-dimensional or two-dimensional decoding is employed.

11. A method for decoding/re-encoding fax information between a sending fax machine and a receiving fax machine comprising:

receiving an encoded fax image defined by rows of scan lines;

decoding the scan lines of the encoded fax image and generating run-length representation of the same;

manipulating the run-length representation to generate a manipulated fax image by without generating a bitmap of the encoded fax image; and

re-encoding the manipulated fax image to generate a re-encoded fax image that is substantially the same as the encoded fax image.

12. A computer readable medium having stored therein computer readable program code comprising instructions for performing the following steps:

receiving an encoded fax image defined by rows of scan lines;

decoding the scan lines of the encoded fax image and generating run-length representation of the same;

manipulating the run-length representation to generate a manipulated fax image by avoiding the generation of a bitmap of the encoded fax image; and

re-encoding the manipulated fax image to generate a re-encoded fax image that is substantially the same as the encoded fax image.

13. A fax decoding/re-encoding system for transferring fax images between a sending fax machine and a receiving fax machine comprising:

means for receiving an encoded fax image defined by rows of scan lines, said decoder for decoding the scan lines of the encoded fax image and generating run-length representation of said encoded fax image;

a scanline manipulation device responsive to said run-length representation for manipulating the same and generating a manipulated fax image without generating a bitmap of the encoded fax image; and

means for receiving said manipulated fax image and adaptive to generate a re-encoded fax image that is substantially the same as the encoded fax image.