How to find the human head from the thermal or gray scale images?

Hi...How to find the human head from the below images or gray scale image?

Thank you.

Answer 1

[Image Analyst]

It should be hotter and larger than anything else. So simply threshold and call bwareafilt()

binaryImage = thermalImage > someTemperature;
binaryImage = bwareafilt(binaryImage, 1); % Take largest blob only.