Re: mark iv compression

[hjohnson@pluto.njcc.com (Herbert R Johnson)]

On Wed, 07 Jun 2000 17:03:28 -0500, Tom Droege <droege@wwa.com> wrote:
*>Herb,
*>
*>As our compression expert, why not try compression with Data Disk 15 which 
*>you also have.  Try it and see what is lost and report back.
*>
*>Below, I don't think that I said I was not keeping the raw data.  I am.  It 
*>is just that I am keeping it after the RawToFits translation which puts it 
*>into .fts format.
*>
*>Tom Droege

Actually I'm "expert" at reporting the work of others on compression, I
have not performed any of the analysis myself. My Tech Note is a compilation
of other's work (with permission of course) other than some ZIP work I did.

Tom, I believe it was your suggestion to *consider* keeping just those pixels
which contribute to the photometry as a *possible* method to reduce the archived
data. Sorry if I misstated this.

But the primary point of my message was to urge compression tests on
REAL Mark IV data, so that the often-discussed "10X" reduction can
be verified - not to mention verifying a method and program to do this. The
Tech Note has almost all the discussion and prior work to date, primarily
on Mark III data and not Mark IV. Tom has pointed out that information
not put into reports or Tech Notes is "lost". It's certainly hard to
review otherwise, which is why I'm keeping on top of this discussion
and maintaining the Tech Note.

Herb Johnson

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