1. A method for estimating the extracorporeal blood volume in a portion of a physical sample, the method comprising: comparing a portion of an image of the sample with a template image of known extracorporeal blood volume indicator; tagging the portion of the image of the sample with a blood volume indicator according to the template image that is matched to the portion of the image of the sample; and estimating the extracorporeal blood volume in at least a portion of the physical sample, associated with the portion of the image of the sample, according to the blood volume indicator.