RE: Puzzle Solution and Compression

[mgutzwiller@lanvision.com]

Tom et al.,

A co-worker of mine actually got interested in compressing Mark III images
using a scheme similar to what Herb suggested.  By dropping the lower 4 bits
and using differences between pixel values he was able to get compression
ratios of about 3.5 to 1.  Dropping the lower 4 bits made no difference to
the Star program's results since the noise was on the order of 6 bits anyway
in my light polluted skies.  A similar approach might be usable for the Mark
IV.

Note that using only the upper 12 bits would still give us a dynamic range
of 4096 to 1.

Mike G.


		-----Original Message-----
		From:	Tom Droege [mailto:droege@fnal.gov]
		Sent:	Wednesday, October 21, 1998 1:57 PM
		To:	tass@wwa.com; hjohnson@pluto.njcc.com
		Subject:	Re: Puzzle Solution

		Herb,

		I hope to get to 10,000 to one.  This is what Lockheed
claims is possible,
		and I hope to get there.  This does not leave much room for
compression.
		Only a few percent will be possible, I think.

		Tom 

		At 12:49 PM 10/21/98 -0400, you wrote:
		>On Tue, 20 Oct 1998 12:04:26 -0500, Tom Droege
<droege@fnal.gov> wrote:
		>*>I would like to congratulate Andrew Bennett for correctly
solving the
		>*>puzzle.  Below is his complete solution:
		>*>
		>*>>
		>*>>It looks a lot like you are getting the wrong high order
		>*>>byte - either the one before or the one after.
		>*>>
		>*>>Andrew Bennett, Avondale Vineyard, Nova Scotia, Canada.
		>*>>
		>
		>Facinating! I was suspecious of a byte order problem: it
did not
		>occur to me casually it was a "byte sequence" problem.
Congratulations!
		>
		>Tom, as you are looking at all the bits, let us know when
you have
		>a measure for the reliable dynamic range of the new design.
We've
		>talked about data compression recently, and a simple
compression
		>scheme would be to remove the lowest and presumably
unreliable bits.
		>And of course it affects small difference measurements and
so on.
		>
		>Herb Johnson
		>
		>Herb Johnson
		>Herbert R. Johnson
http://pluto.njcc.com/~hjohnson
		>hjohnson@pluto.njcc.com         voice 609-771-1503, New
Jersey USA
		>
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