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Re: image contrast, bias a la DS9 [message #70595 is a reply to message #70593]

Thu, 22 April 2010 07:35

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Gray writes:

> The image display/processing program DS9 has a feature where you can
> interactively adjust the colormap of the image by dragging the mouse;
> this changes the colormap's "contrast" (between 0 and 10) and
> "bias" (between 0 and 1). I'd like to be able to reproduce that kind
> of adjustment in IDL (not interactively - I want to be able to apply
> the same adjustments to a number of images), but I'm not sure exactly
> what it is they're doing. Can anyone give me guidance?

I don't have any idea what they are doing, but this sounds
suspiciously similar to "windowing and leveling" an image.
That is, you select a range of image values in the image
(the window) and you center that window at some value
in the image (the level). In your case, contrast is
the window and bias is the level, I would be willing to
bet.

http://www.dfanning.com/ip_tips/contrast.html

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: image contrast, bias a la DS9 By: Craig Markwardt on Thu, 22 April 2010 13:15
		Re: image contrast, bias a la DS9 By: Gray on Thu, 22 April 2010 08:08
		Re: image contrast, bias a la DS9 By: David Fanning on Thu, 22 April 2010 07:35
		Re: image contrast, bias a la DS9 By: JDS on Tue, 27 April 2010 11:27

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