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Re: how to make a mask from a picture and how to put... [message #38411 is a reply to message #38409]

Thu, 04 March 2004 08:57

Thomas Nehls
Messages: 24
Registered: March 2004

Junior Member

David Fanning wrote:

> tom writes:
>
>
>> I want to make a mask from an image containing only some regions of that
>> picture. I already have a black and white image containing these regions.
>> How can I make a mask of it?
>> in order to merge it with or to lay it over an RGB-Image to see only the
>> selected regions from that RGB-Image?
>> thank you very much!
>
>
> Here is an article that describes how to make as mask.
> If your RGB image is 2D, just apply it as described.
> If your RGB image is 24-bit, apply the mask to all three
> 2D image planes.
>
> http://www.dfanning.com/ip_tips/xroi.html
>
> Cheers,
>
> David

thank you that is interesting, but:

I especially want to avoid drawing by hand! I already have my black and
white image bw (1,400,400) which results by some calclations from the
original image "org"(3,400,400).
Now I want to multiply these two images in that way, that everywhere
where my "bw" is black (or white, whatever) should be black in the
resulting image "res". the following loop did not work...
for x=400, Y=400
for X = 1:400
for Y =1:400
res(Z=0:3,X,Y) = bw(X,Y) * org(Z=0:3,X,Y)
end
end
end
Do you understand what I want to do?

what does the following line from your example
(http://www.dfanning.com/ip_tips/xroi.html) do?
IDL> maskedImage = image * (1 - (mask GT 0))

I tried it, but it is not working ...
Thank you!

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[Message index]

		Re: how to make a mask from a picture and how to put... By: Thomas Nehls on Thu, 04 March 2004 10:56
		Re: how to make a mask from a picture and how to put... By: David Fanning on Thu, 04 March 2004 09:25
		Re: how to make a mask from a picture and how to put... By: Thomas Nehls on Thu, 04 March 2004 08:57
		Re: how to make a mask from a picture and how to put... By: David Fanning on Thu, 04 March 2004 05:50

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