How can i calculate over segmentation and under segmentation

i am working on image-segmentation, now i have to calculate over and under segmentation percentage of my result. can anyone please help me how to calculate these ?

[Rik]

Do you have a ground truth? (i.e. an image where you are sure that everything is correctly marked) If so, you still need to define what exactly you mean with over- and under-segmentation. one of several options is:

over=sum(Mask(:)&~GroundTruth(:))/sum(GroundTruth(:));
under=sum(~Mask(:)&GroundTruth(:))/sum(GroundTruth(:));

[rahul verma]

yes i have groung truth

[rahul verma]

Can't i do like this !! by calculating volume,

Vauto = regionprops(Mask, 'Area'); Vmanual = regionprops(groundTruth, 'Area');

where Vauto - volume of My code segmented image. Vmanual = volume of groundTruth image.

even i am trying to do this but i am getting error saying

_______________________Error_______________

Undefined function 'mldivide' for input arguments of type 'struct'.

Error in Over_Under_Seg (line 13) overSegmentation = ((Vauto\Vmanual)\Vmanual);

[Rik]

You are trying to divide two struct, which is not possible. Furthermore, you are aware that you are using after-division? The difference is 1/3=0.3333 and 1\3=3.

If you refuse to use my code, you can use regionprops, but you should still extract the area from the struct. So your line should look like

overSegmentation = ((Vauto.Area\Vmanual.Area)\Vmanual.Area);

This line will only work if there is only a single connected mass in your image.