how do i fit a tight square around an object?

i'm trying to make a size grader for potatoes, and it was the plan to use a picture like

th.jpg

the thing i need to do is try to fit a tight square around each one of the potatoes to determine the "square measurment" this can for instance be "55", then the square is 55x55mm. does anyone know how to do that?

Answer 1

[Image Analyst]

See Steve's blog: http://blogs.mathworks.com/steve/2013/11/19/watershed-transform-question-from-tech-support/

Once you have the potatoes separated, simply use regionprops() to get the area and MajorAxisLength. The bounding box is not a reliable measure of the size because it changes depending on the angle of the potato.

[Image Analyst]

Just search for "fruit" or "vegetable" tag - this comes up all the time and there is code out there.