Altering CT Volume voxel values in Matlab
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I am trying to alter some voxel values in Matlab.
I am using the following code:
for p=1:100
Vol(Vol(:,:,p) > 0) = 65535; %altering voxel values in the volume to 65535 if value > 0.
end
Unfortunately, I find all the values being altered, as if the condition is not working, although if i write Vol(Vol(:,:,1)>0)= 65535 immediately in the command line it works perfectly.
Any clue where the error is??
采纳的回答
It looks like when you use this line:
Vol(Vol(:,:,p) > 0) = 65535
you are in fact referring to a 2D matrix corresponding to a single channel from an image instead of a 3-channel image from your volume. I think it would save you trouble if you used this:
Vol(Vol > 0) = 65535;
instead of your for-loop, since you would then replace all the pixel values greater than 0 with 65535.
EDIT:
I just saw that you asked this question on Stack Overflow, good idea by the way, and that Ray provided a very thorough explanation! Anyhow I hope it is clearer for you now :)
4 个评论
Noha Asas
2014-7-14
Ben11
2014-7-14
Great! If the answer helped you please mark it as accepted :)
If you need to threshold every image individually you can create a matrix containing an 'extra' dimension, so that you can access both the channel AND the image of your choice while looping in the volume. For instance:
% First you might want to initialize the array. Here I declare 'uint16' as the type of data.
Vol = zeros(ImageHeight,ImageWidth,NumberChannels,NumberImages,'uint16') % NumberChannels is probably 3.
for p = 1:100
% Add you code
Vol(Vol(:,:,ChannelofInterest,p) > 0) = 65535;
end
Note that if you want to threshold on all channels you can use rgb2gray(YourImage).
Hope that helps! If not please ask for more details.
Noha Asas
2014-7-23
Ben11
2014-7-24
No problem! Glad I could help :)
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