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Re: color_quan & gif files [message #16561 is a reply to message #16489]

Fri, 30 July 1999 00:00

davidf
Messages: 2866
Registered: September 1996

Senior Member

Liam Gumley (Liam.Gumley@ssec.wisc.edu) writes:

> Indeed, it depends on your application. If you are working with plots,
> David's suggestion no doubt produces better results. However for my
> applications (images), the statistical method seems to work better. I've
> created a couple of test images if anyone is interested. If they seem
> dark, you may wish to view them in an application which allows gamma
> correction.
>
> ftp://origin.ssec.wisc.edu/pub/gumley/test1.gif
> was created with
> image = color_quan(image, 1, r, g, b, colors=256)
>
> ftp://origin.ssec.wisc.edu/pub/gumley/test2.gif
> was created with
> image = color_quan(image, 1, r, g, b, cube=6)
> Note the speckle on the cloud feature to the right of the white box. The
> speckle is more apparent when gamma is adjusted to give a pleasing image
> brightness.

Thanks for these test images, Liam. I guess I'm surprised
there aren't more differences between the two methods for
finding the proper colors. At least to my unexpert eye, the
two images looked remarkably similar. I'm mostly surprised,
I think, because the color tables that come back from the
two methods (viewed, for example, with my CIndex program)
are so *completely* different, although both produce
color tables that are quite a bit different from what
we are used to seeing. :-)

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

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[Message index]

		color_quan & gif files By: Simon Hall on Thu, 29 July 1999 00:00
		Re: color_quan & gif files By: davidf on Fri, 30 July 1999 00:00
		Re: color_quan & gif files By: Liam Gumley on Fri, 30 July 1999 00:00
		Re: color_quan & gif files By: davidf on Fri, 30 July 1999 00:00
		Re: color_quan & gif files By: Liam Gumley on Fri, 30 July 1999 00:00
		Re: color_quan & gif files By: Simon Hall on Fri, 30 July 1999 00:00

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