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Re: Colour maps overlaid on grey-scale (medical) images [message #14683 is a reply to message #14614]

Tue, 23 March 1999 00:00

Vapuser
Messages: 63
Registered: November 1998

Member

davidf@dfanning.com (David Fanning) writes:

> Kenneth P. Bowman (bowman@null.tamu) writes:
>
>> If you use 24-bit color, you can do this by direct manipulation of the RGB
>> values of each pixel.
>
> Yes, well, I have tried this too, but I never seem to get
> results that are completely satisfactory to me. Do you have
> a simple example that shows us *how* to directly manipulate
> the RGB values? I've tried making one image the red channel
> and one the green, etc., but the composite image is not
> really what I want.
>
> I did fool around last week during one of those jet lag
> nights where I was wide awake at 2AM with using the alpha blending
> functionality of an object graphics image. This worked
> surprisingly well after I realized that the documentation
> was just *slightly* misleading, and that the image "color"
> could only come from a 24-bit image.
>
> If I have some time later this week I'll describe what
> I learned in the article on this subject on my web page.
>
> Cheers,
>
> David
>

We have done this sort of thing here (JPL) with clouds over
land/water, using the grayscale of the cloud image as a *mask* of the
land/water image. I've found it easier to do this in HLS; this is a
more natural way to think of the interaction of the cloud/land/water
images. I did this in a completely ad-hoc manner, just trying to get
something that looked good, but I think it could be put on a more
rigorous footing by those more knowledgible in the matter at hand
(medical imagery, in this case) than I.

You can see an example of the method at

http://haifung.jpl.nasa.gov/qs_htdocs/

Scroll to the bottom, to the 'goes overlay' section and pick one of
the two pictures you find. If this interests you, drop me a line.

whd

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[Message index]

		Colour maps overlaid on grey-scale (medical) images By: Jason Brookes on Thu, 11 March 1999 00:00
		Re: Colour maps overlaid on grey-scale (medical) images By: steinhh on Sun, 14 March 1999 00:00
		Re: Colour maps overlaid on grey-scale (medical) images By: bowman on Sat, 13 March 1999 00:00
		Re: Colour maps overlaid on grey-scale (medical) images By: Vapuser on Tue, 23 March 1999 00:00
		Re: Colour maps overlaid on grey-scale (medical) images By: davidf on Mon, 22 March 1999 00:00
		Re: Colour maps overlaid on grey-scale (medical) images By: bowman on Thu, 25 March 1999 00:00

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