Re: mark iv compression

[Chris Albertson <calbertson@logicon.com>]

I had to take a look...

Looks like "ERmapper" and "hcompress" both use a type
of wavelet compression.  See http://www.stsci.edu/software/hcompress.html
Hcompress was designed specifically for astronomical images and allows
the user to specify the level of compression all the way from loss-less to
very high levels.  It is distributed as "C" source code.  

It looks like ERmapper is NOT public domain.  Yes, the company is giving away
some software (maybe in an attempt to promote their data format as a
"standard") but there is no source code and it looks to be for MS Windows PCs
"Public domain" means the author no longer has ANY ownership rights.
Also ERmapper does not appear to handle FITS images.



"Gamble, David" wrote:
> 
> We have been using enhanced compression wavelet for airphotos and
> geophysical images. Compression ratios are very high, ranging from 1:25 to
> 1:50. This is public domain software available from
> http://www.ermapper.com/product/ermapper6/ecw/index.htm. ERmapper also have
<snip>

  Chris Albertson

  calbertson@logicon.com                  Voice: 626-351-0089  x17
  Logicon, Pasadena California            Fax:   626-351-0699