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Image quality

Apr 20, 2009 at 10:20 AM

Original images have some readable text. When uploading and viewing in Silverlight the quality drops so the text on image becomes unreadable.
How to preserve the original quality?
Apr 23, 2009 at 10:05 PM
Edited Apr 24, 2009 at 7:58 PM
So far I have found that images are (always) saved to the jpeg format during the process. Every time the jpeg is saved, it is compressed and every time that compressed image is loaded and compressed again it loses quality quickly.

My suggestion would be to save images in bitmap or tiff format during the process (to preserve original quality) and to the jpeg at the end (final image, compressed, smaller size).

EDIT: Nevermind, I missjudged the image saving process, problem with the quality is somewhere else. Still desperately searching for improvement... Can be something with depth level?
May 6, 2009 at 5:50 AM
with depth level, you can set numbers of layers in pyramid hierarchy. You can reduce number of flies by setting lower number, but qality is lower, too.

Ken Azuma
May 8, 2009 at 7:47 PM
Edited May 8, 2009 at 8:11 PM

Reducing number of layers works fine, but increasing seems to be a problem (throws an exception - something with morton calculation).

Anyway, I had rewritten uploader to ignore database (not needed in a project) and upload multiple files. Problem is when I create a collection xml with Jellyfish tools, there is always width=160 and height=120 in output. Deep Zoom Composer preserves original width and height. Maybe the folders are not specified in the right order or there can be problem with spaces. I must check it again to be sure (to confirm).

EDIT 1: Point is that the quality of images in Silverlight looks the same in Jellyfish (semi-dynamic approach) as in our application. Looks like low compression level of jpeg. Sample

EDIT 2: I've read other discussions - deep zoom composer dll in next version may solve the problem. Anyway, Jellyfish is a good project, I like it.