MATLAB Matrix Indexing - Image Processing

Hello,

I am working on a MATLAB-based image recognition algorithm. However, I run into this problem. Would you mind helping me?

This is a simplified example that I created to illustrate the MATLAB problem that I am facing:

img = [0 0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0 0;0 0 0 0 1 1 0 0 0 0; 0 0 0 0 1 1 1 0 0 0;0 2 2 0 0 1 1 0 0 0; 0 2 2 2 2 0 0 0 0 0;0 0 2 2 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0 0;];
data = randi(255,10,10,50);

How would you get the location of the 1 in matrix img, label the location matrix as loc1, and then get all the values in the matrix data based on location matrix 1? (i.e. the end result should be a nxnx50 matrix)

My next question will be how do you run that procedure in parallel? (i.e. run for value 1 and 2 together)

Thank you so much!

Answer 1

[Jan]

I'm not sure, but maybe you want this:

dataV  = reshape(data, 100, []);
loc1   = (img == 1);
result = dataV(loc1, :);

In parallel? Hm, what does "1 and 2 together" mean? Maybe:

loc1   = (img == 1 || img == 2);

Or simply call the above in a loop? Perhaps a parfor loop?