[Xastir-dev] radar image suggestion

[Gerry Creager n5jxs]

Er... gif files are not compressed within the format, although the LZW 
algorithm is incorporated in the coding.  jpeg images may (and I 
usually) incorporate compression... but it's lossy compression.  PNGs 
are supposed to incorporate lossless compression in their format; I'm 
taking them at their word.  TIFFs are not compressed within their encoding.

Of note, gzipping the tiff reduces its bulk 97+% but it's STILL larger, 
gzip'd, than the jpeg or gif images...

What I'm thinking is that we need to try to go to a PNG format (which 
I'm already creating routinely) to save some 35% of the size of the GIFs.

Simply changing USrad.geo to usr the png file instead of the gif file 
will accomplish this.

Charles R. Twardy wrote:
> Generally, trying to gzip .jpg files will make them larger.
> The same should happen with .gif and .png.
> 
> These are already compressed formats, and the compression is tailored for
> (certain kinds of) images.  Jpeg is tailored for photos, and is usually
> lossy, but Gif will outperform it on line art and low-color images. Png is
> also decent for photos, but is usually lossless. I think it is comparable
> to Gif on low-color images.
> 
> Gif is tailored for line art and relatively low-color images.
> 
> Gzip and cousins are good, but generic. In theory they should almost
> always do worse than the compressed image formats.
> 
> Tif is another story entirely. Always zip the tif.
> 
> 
> GCN>Can we engender an automagic gunzip for the radar images?  I can
> GCN>experiment with gif/tif/png/jpg and determine the best compression rate,
> 
> 
> -Charles
> 


-- 
Gerry Creager -- gerry.creager at tamu.edu
Network Engineering -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020
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