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Re: changing contrast and brightness on the fly [message #25436 is a reply to message #25432]

Fri, 15 June 2001 19:24

Ken Mankoff
Messages: 158
Registered: February 2000

Senior Member

>
> I'm looking for tips on how to implement an image display feature that's
> bugging me. I'm new to widget programming, trying to get up to speed
> with David Fanning's book and other helps, but any short-cuts would be
> appreciated.
>
> The job is to display an MRI image and to be able to adjust the image
> brightness and contrast interactively, without going to any special
> widgets like sliders. The control I have in mind is to
> middle-click the image and then have drag right/left control contrast
> and drag up/down control brightness.
>

I think brightness adjustment is achieved with alpha channels. May require
IDL Object Graphics. There are other ways. Search the groups.google.com
archive for recent threads on this topic.

IDL> ? cursor ; for your
IDL> ? !mouse ; second question.

> It sounds easy but I can't find anything similar described on the web
> etc. to use as a suitable starting point. Question: is changing the
> contrast and brightness to be achieved by re-defining the
> color table and re-scaling the data?

your choice to use data or color scale. use bytscl(), lt & gt to rescale
the data. Probably easier (for debugging too) to do it on data.

-k.

--
Ken Mankoff
LASP://303.492.3264
http://lasp.colorado.edu/~mankoff/

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[Message index]

		changing contrast and brightness on the fly By: Simon Williams on Fri, 15 June 2001 17:13
		Re: changing contrast and brightness on the fly By: david[2] on Fri, 15 June 2001 19:55
		Re: changing contrast and brightness on the fly By: david[2] on Fri, 15 June 2001 19:43
		Re: changing contrast and brightness on the fly By: Ken Mankoff on Fri, 15 June 2001 19:24
		Re: changing contrast and brightness on the fly By: Richard Tyc on Mon, 18 June 2001 07:42
		Re: changing contrast and brightness on the fly By: slashell on Thu, 21 June 2001 09:55
		Re: changing contrast and brightness on the fly By: John-David T. Smith on Wed, 20 June 2001 13:26
		Re: changing contrast and brightness on the fly By: Liam E. Gumley on Wed, 20 June 2001 07:11
		Re: changing contrast and brightness on the fly By: m.hadfield on Mon, 18 June 2001 18:41

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