MATLAB: Pixel position and its value

Question

I have a grayscale image,with four double values 0.25, 0.75 1 and 0.

I need to plot the X-axis co-ordination for each pixel and its intensity (0.25, 0.75, 1 but not 0) . How can Access the X and Y pixel position on the image? is there a straight forward method other than using for loops?

Answer 1

I don't know what "X-axis co-ordination" is. Can you explain. What do you want to do? It's not clear. Do you want to plot an intensity profile between one point and another? If so use improfile().

theProfile = improfile([x1, x2], [y1, y2]);  % Careful - x is column, not row.

Do you want to find all rows where the intensity is more than 0.75? If so:

[rows, columns] = find(grayImage>0.75);

though this is rarely useful or necessary and it's almost always better to just use the binary image

binaryImage = grayImage?0.75;