Lets assume I have a bitmap with a square aspect and width of 2048 pixels.
In order to create a set of files need by Silverlight’s DeepZoomImageTileSource I need to scale this bitmap to 1024 then to 512 then to 256 etc down to 1 pixel image.
There are two, I suspect naive, approaches:-
- For each image required scale the original full size image to the required size. However it seems excessive to be scaling the full image to the very small sizes.
- Having scaled from one level to the next discard the original image and scale each sucessive scaled image as the source of the next smaller image. However I suspect that this would generate images in the 256-64 range with poor fidelity than using option 1.
Note unlike with the Deep Zoom Composer this tool is expected to act in an on-demand fashion hence it needs to complete in a reasonable timeframe (tops 30 seconds). On the pluse side I’m only creating a single multiscale image not a pyramid of mutliple high-res images.
I am outside my comfort zone here, any graphics experts got any advice? Am I wrong about point 2? Is point 1 reasonably performant and I’m worrying about nothing? Option 3?
About 1: This seems the best way. And it is not that excessive if you don’t reload the source image each time.
About 2: Yes, you would looses (some) quality by scaling in steps.
I think 30 sec should be sufficient to scale a picture (a few times). Any optimization would be in the area of caching the results.