This is common in image processing and you can use a similar process to extract your features. Using the image attachted if you run the following commands:
I = imread('Voxels.png');
>> 916 800 3
You can see the matrix is 916x800x3. Here the image is 916x800 pixels. The image is made out of red, green, and blue pixels of different ratios to make a specified color (hence the 3). So if I only wanted to extract the red components I would run:
Similarly I could put 2 and 3 to get blue and green components respectively.
If the image was a gif it would be 916x800x3xN where N would be a frame like in a video. If I wanted the last red frame I could run:
So in your case simply to extract all the features you could run a loop like this:
for ii = 1:60
for jj = 1:14
You might be better off to store the results in a cell array but it all depends on how you plan on analyzing your results (so ill leave that up to you). Hope this helped.