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Re: Map transparent image [message #35699 is a reply to message #35684]

Tue, 01 July 2003 06:24

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Haje Korth writes:

> I am trying to overlay a grey-shaded mask over an image to indicate areas
> where sample data are less reliable. However, I want the grey shaded area to
> be transparent so that I can still see the underlying data points. I do not
> want to use 'contour' since the results look rather confusing; too many
> patches. As far as I can see, the IDL map_image command does not provide
> such settings. Does anyone know, how the mask can be worked into the image
> prior to display? What is the math that one would apply?

There is a pixelation technique described in this article
that I think would work:

http://www.dfanning.com/color_tips/color_overlay.html

Create two images: one normal and the other normal with
the gray mask opaquely on top. Then pixelate the two.
You should end up with an image in which the colors show
through the gray, where the gray is present and looks normal
otherwise.

Cheers,

David

P.S. I haven't tried this, but sometimes you just
feel extraordinarily confident something is going to
work. :-)

--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@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]

		Re: Map transparent image By: Haje Korth on Tue, 01 July 2003 12:50
		Re: Map transparent image By: Haje Korth on Tue, 01 July 2003 12:49
		Re: Map transparent image By: Haje Korth on Tue, 01 July 2003 12:43
		Re: Map transparent image By: David Fanning on Tue, 01 July 2003 12:51
		Re: Map transparent image By: mmiller3 on Tue, 01 July 2003 12:22
		Re: Map transparent image By: Andy Loughe ( remove on Tue, 01 July 2003 07:46
		Re: Map transparent image By: David Fanning on Tue, 01 July 2003 11:12
		Re: Map transparent image By: Haje Korth on Tue, 01 July 2003 10:45
		Re: Map transparent image By: David Fanning on Tue, 01 July 2003 08:26
		Re: Map transparent image By: Haje Korth on Tue, 01 July 2003 08:04
		Re: Map transparent image By: David Fanning on Tue, 01 July 2003 06:24

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