So I have a video of bacterial cells moving around which I converted to frames. Now I want to find the instantaneous velocity of each bacterial cells. For this I am interested in finding by how much a bacterial cell moved but I dont know how to tell my programme to accurately identify that this specific bacteria moved. For example, lets say I have only two images. For each image, I have the COM coordinate of each bacteria. Now how do I relate this data. How do I ask my programme to accurately identify that this much was the change in COM for this specific bacteria. I have attached the two images for reference.