How to measure the size for an irregular object on a binary image ? such perimeter and length

[darova]

did you try boundary or convhull?

[eissam salem]

I try it but i got confused, because some of my images are rotated !

Answer 1

[Image Analyst]

For perimeters, use regionprops()

props = regionprops(mask, 'Perimeter');
allPerimeters = [props.Perimeter]

For Feret diameters (lengths), use bwferet().

If you want to extract only the largest blob, use bwareafilt

mask = bwareafilt(mask, 1);

[eissam salem]

Can you give me more details, I am not expert.

thank you

[Image Analyst]

See my well commented Image Segmentation Tutorial in my File Exchange.