[gdal-dev] Question on image formats vs performance and quality

[Stephen Woodbridge]

Hi all,

I would be interest in you thoughts on comparing MrSID, ECW, and Tiff 
images from the perspective of image quality and performance.

The scenario is I have imagery in MrSID. I typically decompress that 
into Tiled Tiff uncompressed imagery with overviews. I server it via 
mapserver and it has reasonable performance.

I have not considered serving it from the MrSID files because I don't 
have a license to compress the files and I would need to reproject them. 
Also I'm guessing it in not a good idea to uncompress and compress them 
again as it is lossy and the image degrades.

I have never worked with ECW, but I'm concerned about:
1) ECW is 8-bit data only and the source data is 24 bit RGB data
2) how does it compare performance wise to say the tiff images when 
rendering?

Are there other formats that would be good to consider? What are their 
characteristics?

Thanks,
   -Steve