Find pixel intensity with coordinates?

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

[Matt J]

pixelValues=yourImage(  sub2ind(size(yourImage),X,Y)   );

keep=(pixelValues>=threshold);

X=X(keep);
Y=Y(keep);

[valerio auricchio]

I do not understand why X=X(keep) is not taking the coordinates in the vectro x in the threshold but all value that are 1

[Rik]

What do you mean? Are you talking about the values of the keep array itself?

[valerio auricchio]

Solved thx a lot!