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Resolved

Should we be using PNG's instead of JPEGs?

description

I've been using jpeg's up to now. Which is better - png or jpeg as far as the SIT is concerned? Or does it not matter much?
 
Some background; In the creation of a sparse image with the DZI we deal with three images: input (your JPGs), intermediate when we convert each input image to a non-sparse DZI and then the output DZI which is a sparse composition of the intermediate images.
 
My advice is to use PNG for the first two.
 
  1. Try to scan or extract your input materials to a PNG format.
     
  2. Convert the input PNGs to DZI’s images with PNG tiles, using the ImageTool (part of the DeepZoomComposer distribution). The correct command line is something like:
     
    ImageTool.exe convert <inputfile> png
     
  3. Add the non-sparse DZI images (from step 2) to the scene graph file and run SIT.
     
    This will ensure that there is no quality degradation from compressing/decompressing lossy JPGs.
     
    For the output image you need to balance the quality of PNG versus the size reduction of the JPG tiles. My suggestion is try them out both and choose the correct format for your needs. You might also want to try with different quality levels when encoding JPG tiles.

comments

gwatts wrote Mar 20, 2010 at 6:23 AM

jpeg is better for continuous tone images, and png for things that aren't. Slides tend to mostly be single tone... png is lossless... so - we shoudl switch to that, I guess!

gwatts wrote Mar 20, 2010 at 6:26 AM

According to writeup - compression above 0.9 will not really make a visible difference. So that is what we shoudl run and compare a talk at.

wrote May 1, 2010 at 8:41 PM

wrote Feb 2, 2013 at 3:05 AM

wrote May 15, 2013 at 11:27 PM

wrote May 15, 2013 at 11:27 PM

wrote Jun 12, 2013 at 12:42 AM