how to detect humans in thermovision images?

edit

i have a set of images from a thermovision video stream. i want to be able to detect humans in these images. A sample of an image is attached C:\fakepath\Selection_033.png. There is a human in front of the building in centre of image. How can i use open-cv to detect this person who is in different positions in all images? can i use any pre-trained models? i am quite new in this domain so any help will be appreciated