System and method for editing digital images using inductive image generation with cached state-specific image tiles
A system and method using inductive image generation with cached, state-specific image tiles for editing digital images. A computer system contains an archival digital image to be edited and viewed, a transformation state list, describing editing operations to be applied to the archival image in order to produce the current edited image rendition, and a viewing data set, describing the resolution, offset and extent of the current view of the current edited image rendition. The current view is constructed from a set of image tiles kept in a tile cache. In response to an instruction to generate the current view, the system identifies the requisite tiles, and then generates each tile by an inductive image generation process. The latter process comprises (a) ascertaining if the tile is in the tile cache, and, if not (b) ascertaining if the image is unedited and if so obtaining the requisite tile from the image file, and, if not (c) generating the tile by identifying and assembling the requisite supplier tiles in the previous state of the image-editing process and by then applying the current state's editing transformation function to the supplier tiles. The inductive image-generation process is recursive in that in case it is necessary to assemble supplier tiles in the course of the inductive image-generation process then they too are assembled by the process of inductive image generation.
1. A method for interactively viewing and editing a digital image on a computer system comprising the steps of:
storing an archival digital image in the computer system;
maintaining in the computer system a state list, characterizing a sequence of image-editing operations to be applied to the archival digital image in order to generate a current edited rendition of the digital image;
maintaining in the computer system a set of viewing data, chracterizing the resolution, offset and extent at which to view the current edited rendition of the archival digital image;
maintaining in the computer system a cache of image tiles comprising portions of views of edited renditions of the archival digital image, wherein each image tile is associated with a state in the list; and thereafter
updating, in response to image-viewing and image-editing instructions, the viewing data and the state list accordingly, and
assembling in the image tile cache in response to image-viewing and image-editing instructions, a set of image tiles sufficient to generate the current view of the current edited rendition of the archival digital image, wherein assembling comprises using the stare list to compute a current tile based on an image tile associated with a previous state.
2. The method of claim 1 wherein said step of assembling includes a step for each tile in the set of image tiles, comprises
a) locking the tile in the tile cache when it is ascertained that the tile is in the tile cache;
b) generating the tile from the archival digital image, copying the generated tile into the tile cache, and locking the copied tile in the tile cache when it is ascertained that a current image state is an initial unedited state; and
c1) ascertaining, when the tile is not in the tile cache or when the current image state is not in the initial unedited state, a set of supplier tiles in a prior stare sufficient so that the tile can be generated from the set of supplier tiles by application of the image viewing and image-editing instructions, and
c2) assembling the second set of supplier tiles, and
c3) applying the image-viewing and image-editing instructions to the set of supplier tiles so as to generate the tile and copying the generated tile into the tile cache, and locking the copied tile in the tile cache.
3. The method of claim 2 wherein the supplier tiles in the prior state are assembled, for each tile in the set of supplier tiles, by:
a) locking the tile in the tile cache when it is ascertained that the tile is in the tile cache;
b) generating the tile from the archival digital image, copying the generated tile into the tile cache, and locking the copied tile in the tile cache when it is ascertained that a current image state is an initial unedited state; and
c1) ascertaining, when the tile is not in the tile cache or when the current image state is not in the initial unedited stage, a second set of supplier tiles in a prior stare sufficient so that the tile can be generated from the second set of supplier tiles by application of the image-viewing and image-editing instructions of the prior state, and
c2) assembling the second set of supplier tiles, and
c3) applying the image-viewing and image-editing instructions of the prior state to the second set of supplier tiles so as to generate the tile and copying the generated tile into the tile cache, and locking the copied tile in the tile cache.
4. The method of claim 2 wherein assembling the set of supplier tiles of a tile in the set of image tiles comprises:
a) ascertaining the region in the prior state from which the tile in the set of image tiles is generated, and
b) ascertaining the set of prior-state tiles intersecting the region, and
c) assembling all the supplier tiles in the set.
5. The method of claim 4 wherein assembling the set of supplier tiles of a tile in the set of supplier tiles comprises:
a) ascertaining the region in the prior state from which the tile in the set of supplier tiles is generated, and
b) ascertaining the set of prior-state tiles intersecting the region, and
c) assembling all the supplier tiles in the set.
6. The method of claim 1 wherein the image-viewing instructions specify the extent of the view of the current edited rendition of the digital image by explicitly identifying the tiles to be viewed.
7. The method of claim 1 wherein the image-viewing instructions specify the extent of the view of the current edited rendition of the digital image by identifying the region to be viewed, whereupon the addresses of all tiles intersecting the region are computed.
8. The method of claim 1 additionally comprising copying the set of image tiles sufficient to generate the current view of the current edited rendition of the archival digital image into the computer system's video display buffer so as to generate the current view of the edited rendition of the archival digital image.
9. The method as recited in claim 1 wherein the previous state is between an anchor state and a current state.
10. The method as recited in claim 1 wherein the cache of images tiles include portions of views of multiple edited renditions.
11. A computer system for interactively viewing and editing a digital image comprising:
an electronic digital-data storage device, operative to hold a plurality of archival digital images;
a state list, characterizing a sequence of image-editing operations to be applied
to a given archival digital image in order to generate a current edited rendition of the digital image,
a set of viewing data, characterizing the resolution, offset and extent at which to view the current edited rendition of the given digital image;
a cache of image tiles comprising portions of views of edited renditions of the archival digital image, each tile identifying a state in the state list,
a video digital display device;
a digital video memory buffer, containing digital data displayed by the video
digital display device;
a user-input device;
a user-input module, operative to receive signals from the user-input device and translate them into image-viewing and image-editing instructions; and
an application module, operative
to receive image-viewing and image-editing instructions from the user-input module, and
to update the viewing data and the state list in response to the image-viewing and image-editing instructions, and
to assemble in the system's tile cache in response to the image-viewing and image-editing instructions, a set of image tiles sufficient to generate the current view of the current edited rendition of the archival digital image by using the state list, and
to copy the set of image tiles sufficient to generate the current view of the current edited rendition of the archival digital image into the computer system's video display buffer so as to generate the current view of the edited rendition of the archival digital image.
12. The computer System of claim 11 wherein the computer system comprises a plurality of computers connected by a network.
13. The computer system of claim 12 wherein the network is the Internet.
14. The computer system of claim 12 wherein the electronic digital-data storage device, the state list, the set of viewing data, and the cache of image tiles reside in a first server computer, wherein the video digital display device, the digital video memory buffer, the user-input devices, and the user-input module reside in a second client computer, and wherein the application module is partitioned into a server application submodule resident in the server computer and a client application submodule resident in the client's computer.
15. The computer system of claim 14 wherein the client application submodule is operative:
to receive image-viewing and image-editing instructions from the user-input module, and
to transmit the image-viewing and image-editing instructions to the server application submodule.
16. The computer system of claim 14 wherein the server application submodule is operative:
to receive image-viewing and image-editing instructions from the client application submodule, and
to update the viewing data and the state list accordingly, and
to assemble in the tile cache, by inductive image generation and in response to image-viewing and image-editing instructions, a set of image tiles sufficient to generate the current view of the current edited rendition of the archival digital image, and
to transmit the set of image tiles to the client applications submodule.
17. The computer system of claim 14 wherein the client application submodule is operative:
to receive image tiles sufficient to generate the current view of the current edited rendition of the archival digital image transmitted from the server application submodule, and
to copy the set of image tiles sufficient to generate the current view of the current edited rendition of the archival digital image into the computer system's video display buffer so as to generate the current view of the edited rendition of the archival image.
18. The computer system of claim 14 additionally comprising a second cache of image tiles residing in the client computer.