Re: New FITS greyscale mapping

[Nicholas Beser <beser@aplcomm.jhuapl.edu>]

Chris Albertson wrote:

> Nick,
>
> I added a better greyscale mapper to my FITS->PGM program.
> Mk III images look much better now.  Many hundreds of stars
> now show up.  But so do all the typical Mk III image defects.
> I do a type of log scaling.  There is a constant "k" that is
> used to adjust the contrast by selecting the part of the log
> function used for mapping.  Low values of k do an extreme
> wrapping while high values make the picture look a uniform
> middle gray.  The value of K in the posted program was set
> by eye using images from my camera.  Images from Glenn's
> or Tom's camera require small changes to k to look their
> best.  Just change the constant and re-compile until you
> like the result.  k is set about half way down in the
> "main" routine. There is a big comment block pointing it
> out.
>

I ran into some problems with the program so I went back to the older
version and experimented with the standard deviation approach. After I
corrected the values for 32768, added a few include files (the older
version did not have math.h included) everything looked pretty good. I
am going to clean it up a bit (add a pgm output), and then try a few
experiments on the web page.

Nick

>
> The program is at:
> ftp://ftp.logicon.com/open/fits2raw-21mar99.tgz
>
> There is another program with a similar name
> ftp://ftp.logicon.com/open/fits2pg-0.1.0.tgz
> This program does automatic conversion for FITS table files
> to Postgree database tables.
>
> --
>    --Chris Albertson             home: chrisja@jps.net
>      Redondo Beach, California   work: chris@topdog.logicon.com