What program measures the length ratio of objects in a photo?

Question

Photo

Hello!
I really need a program to measure the ratio of the length of the fingers on the hand in the photo. The program should be light and easy to use, as it is needed by people with a medical background, not programmers. Please let me know if there is one and where I can find it.

Answer 1

not quite, you need a length ratio, for example, the thumb and forefinger are related as 1: 1.3