SYSTEM AND METHOD FOR GENERATING VISUAL REPRESENTATIONS OF GRAPHICAL DATA AND DIGITAL DOCUMENT PROCESSING

1 . A method of generating a visual display of graphical data, said graphical data comprising a plurality of graphical elements, and the visual display of said graphical data being derived from source data that encodes said graphical elements in a predetermined data format and which is processed to enable full quality on-screen rendering of said graphical elements, the method comprising:

retrieving and displaying an initial approximate visual representation of the graphical data;

progressively retrieving and displaying the elements of the graphical data at full quality; and

while at least one of the graphical data is being retrieved and the source data is being processed for full quality on-screen rendering, progressively updating the display by blending the approximate representation with elements of the graphical data that have been retrieved for full quality display, wherein blending presents the approximate representation as a partially transparent overlay on top of the retrieved elements of graphical data.

2 . A method according to claim 1 , wherein the approximate representation and the retrieved elements of graphical data are blended by combining pixel values of the approximate representation and corresponding pixel values of the retrieved elements according to a predetermined weighting factor.

3 . A method according to claim 1 , wherein the display is progressively updated in multiple steps until all of the elements of the graphical data have been retrieved to provide a complete, full quality on-screen rendering of the graphical data.

4 . A method according to claim 2 , wherein the display is progressively updated in multiple steps until all of the elements of the graphical data have been retrieved to provide a complete, full quality on-screen rendering of the graphical data, and wherein the weighting factor is progressively adjusted to reduce the weighting of the approximate representation.

5 . A method according to claim 3 , wherein the display is updated at predetermined intervals.

6 . A method according to claim 3 , wherein the display is updated at variable intervals as one or more graphical elements are retrieved.

7 . A method according to claim 1 , wherein the approximate representation is replaced by successively better quality approximate representations at selected display updates.

8 . A method according to claim 1 , wherein the initial approximate representation and any subsequent better quality approximate representations comprise at least one of a text label, an icon and a reduced resolution bitmap of the graphical data.

9 . A method according to claim 1 , wherein the source data represents an ordered stack of graphical elements.

10 . A method according to claim 1 , wherein the source data includes the initial approximate representation and any subsequent better quality approximate representations.

11 . A method according to claim 1 , wherein the initial approximate representation and any subsequent better quality approximate representations are generated from the source data.

12 . A method according to claim 1 , wherein the source data is stored in a server and the display is at a client connected to the server.

13 . A method according to claim 12 , wherein the source data is processed by the server and the graphical elements are transmitted from the server to the client.

14 . A method according to claim 13 , wherein the source data is processed by the server to generate a stream of graphical elements that are to be displayed and said stream is transmitted from the server to the client.

15 . A method according to claim 12 , wherein the source data is transmitted from the server to the client and processed by the client.

16 . A method according to claim 14 , wherein at least one approximate visual representation of the graphical data is included in the stream of graphical elements.

17 . A system of generating a visual display of graphical data, said graphical data comprising a plurality of graphical elements, and the visual display of said graphical data being derived from source data that encodes said graphical elements in a predetermined data format and which is processed to enable full quality on-screen rendering of said graphical elements, the system comprising:

a controller that controls the following operations:

retrieving and displaying on the visual display an initial approximate visual representation of the graphical data;

progressively retrieving and displaying on the visual display the elements of the graphical data at full quality; and

while at least one of the graphical data is being retrieved and the source data is being processed for full quality on-screen rendering, progressively updating the visual display by blending the approximate representation with elements of the graphical data that have been retrieved for full quality display, wherein blending presents the approximate representation as a partially transparent overlay on top of the retrieved elements of graphical data.

18 . A system according to claim 17 , comprising a client-server system wherein the server stores the source data and the client includes the visual display.

19 . A system according to claim 18 , wherein the server processes the source data and operates to transmit the graphical elements to the client.

20 . A system according to claim 19 , wherein the graphical elements transmitted from the server to the client includes at least one approximate visual representation of the graphical data.

21 . A system according to claim 18 , wherein the server operates to transmit the source data to the client and the client processes the source data.

22 . A computer program embodied on a recordable medium for controlling a computer to perform the method according to claim 1 .