Did you mean diffentiating tissue? Yes, that is true. You can use ISO levels from the images to segment different density regions, which is more or less what a

Did you mean diffentiating tissue? Yes, that is true. You can use ISO levels from the images to segment different density regions, which is more or less what a doctor would do, AFAIK. Usually the entire picture is non-zero, so you have to set a cutoff somewhere in order to get a real blob.