1. A method for estimating the extracorporeal blood volume in a portion of a physical sample, the method comprising: extracting a feature from a portion of an image of the sample; tagging the portion of the image of the sample with a blood volume indicator according to the extracted feature; and estimating the extracorporeal blood volume in at least the portion of the physical sample, associated with the portion of the image of the sample, according to the blood volume indicator.