Storing pixel information in 4D array..

Hi,

So I have a set (a stack?) of 2D images and I have them stored in a 3D array. I now want to compare pixel values throughout the images, so I would compare...

images(1,1,1), images(1,1,2), images(1,1,3) etc...

and then

images(1,2,1), images(1,2,2), images(1,2,3) etc...

So far I have...

for j = 1:length(dat) [img, map] = dicomread(char(dat(j,1))); images(:,:,j) = img; end

valsZ = cell(size(images, 3), 2); valsX = cell(size(images, 3), 2, size(images, 2));

    for x = 1:size(images, 2)
        for z = 1:size(images, 3)            
            imgVal = images(y,x,z);
            valsZ(z,:) = {z, imgVal};            
        end
        valsX(x,:,:) = {x, valsZ(1,:), valsZ(2,:)};    
end

I think I would need to create a 4D array to store the pixel information so that I have a 2D array of pixel value and image number within a 3D array that defines which column the data is in and then a 4D array for which row the data is in.

At the moment I am getting a 'Subscripted assignment dimension mismatch' error for valsX. Any help would be great! Thanks!

Answer 1

[Stephen23]

It sounds complicated. Why not just use the images array that you have now? MATLAB indexing lets you access rows and slices of any matrix or array, very easily. For example, to get these values in a vector:

images(1,1,1), images(1,1,2), images(1,1,3), etc

just use

images(1,1,:)

which you can then use to perform any kind of comparison or operation on, including any vectorized operations .

[Shaun]

Thanks, I did try that but not in the right way!!