I have a 2D array over the range xmin<x<xmax and ymin<y<ymax which contains the color intensity of each point. It looks like a deformed donut. I needed to find the inner and outer boundary of the donut. In order to achieve this goal, I used image processing and found the boundaries by bwboundaries function. Now I have the boundaries. The boundaries are in rows and columns coordinate. I want to convert them back into physical x,y coordinates. How can I do it?