How i can find the size in mm of all blobs in a binary image????

[Rik]

What do you mean with size? Area? Tip to tip distance? Something else?

And what is the size of your pixels? If you don't have the size of the pixels, you can only measure the blob size in pixel units.

Answer 1

[Image Analyst]

See my Image Segmentation Tutorial: My File Exchange

That will show you how to get areas and diameters in pixels.

When you get the areas from regionprops, multiply by your mmPerPixel calibration factor. When you get the diameter or distances, multiply theb your mmPerPixel squared. See my attached spatial calibration demo.