MATLAB: Find pixel intensity with coordinates

Question

I have two vector:

X[12 34 12 22]

Y[2 3 44 5]

They rappresent the coordinates (x,y) of a pixel. I want to know the intensity of each pixel and eliminate the pixel that have intensity lower than a value.

Answer 1

pixelValues=yourImage(  sub2ind(size(yourImage),X,Y)   );
keep=(pixelValues>=threshold);
X=X(keep);
Y=Y(keep);