Compare image segmentation approaches
Typically to compare segmentation algorithms, people use an NPR index. NPR stands for Normalized Probabilistic Rand.

An over segmented or an under-segmented image will typically have negative values of NPR whereas a properly segmented image will have positive values of NPR index.

This type of comparison is typically carried out for segmentation algorithms of the split-and-merge type.

Following this paper and the further publications of the group would be advantageous.