Fast method for fax encoded data conversion

• US 8,035,862 B2
• Filed: 05/16/2005
• Issued: 10/11/2011
• Est. Priority Date: 12/20/2000
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Gurevich, Vladimir Alexandrovich
• Primary Examiner(s): Worku; Negussie
• Application Number:
  US11/130,580
• Publication Number:
  US 20050213164A1
• Time in Patent Office: 2,339 Days
• Field of Search: 358/474, 358/1.15, 358/442, 358/400, 358/3, 358/27, 358/1.2, 358/451, 358/426.16, 358/426.07, 358/539, 358/401, 382/171, 382/232, 382/233, 382/299, 382/300, 382/269, 375/240.03, 375/240.25, 375/240.05
• 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 the 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 system comprising:

a transmitting fax machine configured to encode a fax image and transmit the encoded image;

an electronic device configured to receive the encoded image from the transmitting fax machine over a first connection, the electronic device comprising;

a decoder for decoding scan lines of the encoded fax image and generating a run-length representation of the encoded fax image;

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

a re-encoder responsive to the manipulated fax image to generate a re-encoded fax image; and

a receiving fax machine configured to receive the re-encoded fax image over a second connection.

2. A system as recited in claim 1 wherein Group 3 is used for transmission of the fax image between the transmitting fax machine and the receiving fax machine.

3. A 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, the 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 the 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.

4. A system as recited in claim 3 wherein the decoder further includes a two-dimensional decoder responsive to the encoded fax image for two-dimensional decoding of the same.

5. A system as recited in claim 4 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.

6. A system as recited in claim 5 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.

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

8. A system as recited in claim 7 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.

9. A system as recited in claim 1 wherein the 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.

10. A system as recited in claim 1 wherein the electronic device is an access server.

11. An access server, comprising:

a decoder for decoding scan lines of the encoded fax image and generating a run-length representation of an encoded fax image received from a transmitting fax machine;

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

a re-encoder responsive to the manipulated fax image to generate a re-encoded fax image to be sent to a receiving fax machine.

12. An access server as recited in claim 11 wherein the decoder further includes a one-dimensional decoder and a one-dimensional run-length representation block coupled to the one-dimensional decoder, the 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 the 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.

13. An access server as recited in claim 12 wherein the decoder further includes a two-dimensional decoder responsive to the encoded fax image for two-dimensional decoding of the same.

14. An access server as recited in claim 13 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.

15. An access server as recited in claim 14 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.

16. An access server as recited in claim 11 wherein the decoder includes a one-dimensional decoder responsive to the scan lines of the encoded fax image for one dimensionally decoding the scan lines and wherein the decoder further includes a two dimensional decoder responsive to the scan lines of the encoded fax image for two dimensionally decoding the scan lines wherein the decoder selectively decodes the encoded fax image using either the one-dimensional decoder or the two-dimensional decoder.

17. An access server as recited in claim 16 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.

18. An access server as recited in claim 11 wherein the 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.

19. A method for decoding/re-encoding fax information comprising:

receiving from a transmitting fax machine 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 without generating a bitmap of the encoded fax image;

re-encoding the manipulated fax image to generate a re-encoded fax image; and

sending the re-encoded fax image to a receiving fax machine.

20. A non-transitory computer readable medium having stored therein computer readable program code comprising instructions for performing the following:

receiving from a transmitting fax machine 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;

re-encoding the manipulated fax image to generate a re-encoded fax image; and

sending the re-encoded fax image to a receiving fax machine.

21. A system comprising:

means for receiving from a transmitting fax machine an encoded fax image defined by rows of scan lines;

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

means for manipulating the run-length representation and generating a manipulated fax image without generating a bitmap of the encoded fax image;

means for receiving the manipulated fax image and adaptive to generate a re-encoded fax image; and

means for sending the re-encoded fax image to a receiving fax machine.