Image transfer optimisation

• US 20020051583A1
• Filed: 10/25/2001
• Published: 05/02/2002
• Est. Priority Date: 10/30/2000
• Status: Active Grant

• Current Assignee: G4S Monitoring Technologies Limited (G4S PLC)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Brown, Craig Matthew, Andrew, James Philip, Onno, Patrice Jean Paul
• Granted Patent: US 7,212,678 B2
• Time in Patent Office: Days
• US Class Current: 382/299
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform

Abstract

A method of retrieving an image for display is disclosed. The image is stored in a compressed wavelet-based format having blocks encoded substantially independently. Initially, a representation (1300) of the image is provided at a first (low) resolution (1302). The user can then select a portion (1308) of the representation for reproduction at a predetermined, generally a second (higher), resolution. A first set of blocks is then identified (1322) corresponding to the selected portion(1310), which are then retrieved, decompressed and rendered to display. A second set of blocks (associated with the first set of blocks) is then identified (1326-1340), retrieved and decompressed. The rendered first set of blocks is then modified using the decompressed second set and displayed at the predetermined/second resolution.

Claims

1. A method of retrieving an image for display, the image being stored in a compressed wavelet-based format having blocks encoded substantially independently, said method comprising the steps of:

selecting a portion of said image for reproduction at a predetermined resolution;

identifying a first set of said blocks corresponding to said selected portion;

retrieving said first set of blocks, decompressing and rendering same to display;

identifying a second set of blocks associated with said first set of blocks;

retrieving said second set of blocks and decompressing the same; and

modifying said rendered first set using the decompressed second set and displaying the modified selected portion at said predetermined resolution.

2. A method of retrieving an image for display, the image being stored in a compressed wavelet-based format having blocks encoded substantially independently, said method comprising the steps of:

(a) providing a representation of said image at a first (low) resolution;

(b) identifying a selected portion of said representation for reproduction at a second (higher) resolution;

(c) identifying a first set of said blocks corresponding to said selected portion;

(d) retrieving, decompressing and rendering said first set of blocks to display;

(e) identifying a second set of blocks associated with said first set of blocks;

(f) retrieving and decompressing said second set of blocks; and

(g) modifying said display of the selected portion at said second resolution in accordance with both the first and second sets of blocks.

3. A method according to claim 2, wherein steps (d) and (e) occur substantially simultaneously.

4. A method according to claim 2, wherein step (d) comprises, for peripheral pixels in said first set of blocks for which high frequency components required for representation at said second resolution are unavailable, setting said high frequency components to a predetermined value and rendering those said pixels at an intermediate resolution between said first resolution and said second resolution.

5. A method according to claim 4, wherein said predetermined value is zero.

6. A method according to claim 4, wherein step (g) comprises modifying said peripheral pixels.

7. A method according to claim 2 wherein step (e) comprises identifying those said blocks that surround said first set of blocks.

8. A method according to claim 2 wherein step (e) comprises identifying those said blocks, not members of said first set, that influence a reproduction of the first set of blocks at the second resolution.

9. A method according to claim 2 wherein step (e) comprises determining a priority order within said second set of blocks and step (f) comprises retrieving said second set of blocks in said priority order.

10. A method according to claim 9 wherein said second set is divided into sub-sets according to said priority order and said sub-sets are retrieved ion said priority order.

11. A method according to claim 10 wherein a retrieval of each said set or sub-set is associated with a corresponding request for blocks within said set or sub-set.

12. A method according to claim 2, wherein said retrieval of said blocks occurs over a computer network.

15. A computer readable medium according to claim 14 further comprising:

code for determining a priority order of said second set of blocks and for transmitting said identification in said priority order.

16. A computer readable medium according to claim 14 further comprising:

code for requesting delivery of a remainder of blocks of said image at said second resolution.

18. A computer readable medium according to claim 17 further comprising:

code for transmitting to said client computer a remainder of blocks of said image at said second resolution.

13. A computer readable medium comprising a computer program for retrieving an image for display, the image being stored in a compressed wavelet-based format having blocks encoded substantially independently, said program comprising:

code for providing a representation of said image at a first (low) resolution;

code for identifying a selected portion of said representation for reproduction at a second (higher) resolution;

code for identifying a first set of said blocks corresponding to said selected portion;

code for retrieving, decompressing and rendering said first set of blocks to display;

code for identifying a second set of blocks associated with said first set of blocks;

code for retrieving and decompressing said second set of blocks;

code for modifying said rendered first set using the decompressed second set to thereby display a representation of said selected portion at said second resolution.

14. A computer readable medium comprising a computer program for retrieving an image for display, the image being stored in a compressed wavelet-based format having blocks encoded substantially independently, said program being operable upon a client computer and comprising:

code for providing a representation of said image at a first (low) resolution;

code for identifying a selected portion of said representation for reproduction at a second (higher) resolution;

code for identifying a first set of said blocks corresponding to said selected portion;

code for transmitting an identification of the first set of blocks to a source of said image;

code for receiving from said source blocks of image data corresponding to said first set of blocks and for decompressing said received blocks at said second resolution and rendering same to display;

code for identifying a second set of blocks associated with said first set of blocks;

code for transmitting an identification of the second set of blocks to said source;

code for receiving from said source further blocks of image data corresponding to said second set of blocks; and

code for modifying said first rendered blocks using a decompression of said further blocks to thereby display a representation of said selected portion at said second resolution.

17. A computer readable medium comprising a computer program for delivering an image for display, the image being stored in a compressed wavelet-based format having blocks encoded substantially independently, said program being operable upon a server computer at which said image is stored and comprising:

code for supplying to a client computer a representation of said image at a first (low) resolution;

code for receiving from said client computer an identification of the first set of blocks in said first resolution of said image;

code for determining from said identification of said first set of blocks, corresponding blocks of said stored image at a second (higher) resolution;

code for transmitting said corresponding blocks to said client computer;

code for receiving from said client computer an identification of the second set of blocks in said first resolution of said image;

code for determining from said identification of said second set of blocks, corresponding further blocks of said stored image at a second (higher) resolution; and

code for transmitting said corresponding further blocks to said client computer.

19. Apparatus for retrieving an image for display, the image being stored in a compressed wavelet-based format having blocks encoded substantially independently, said apparatus comprising:

a representation unit which represents said image at a first (low) resolution;

a first identification unit for identifying a selected portion of said image for reproduction at a second (higher) resolution;

a second identification unit for identifying a first set of said blocks corresponding to said selected portion;

a first retrieval unit for retrieving, decompressing and rendering said first set of blocks to display;

a third identification unit for identifying a second set of blocks associated with said first set of blocks;

a second retrieval unit for retrieving and decompressing said second set of blocks; and

a modification unit for modifying said rendered first set using the decompressed second set and displaying the modified selected portion at said second resolution.