Hi, you have to binarize the image with im2bw than you can use some function to be sure that all elements are non connected like imerode than you have to close contour and fill holes using imclose imfill
at this stage maybe a denoising step with bwareaopen is appreciable
and finally you cal extract all properties with regionprops
simply you can ceck the perimeter or the roundness of you m&m, maybe the minimum axes should be the solution if minimun axex< threshold is broken
Best.
