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; wherein extracting the feature from the portion of the image of the sample comprises extracting the feature that comprises a color intensity value in a component space; and wherein tagging the portion of the image of the sample with the blood volume indicator comprises transforming the extracted feature into the blood volume indicator according to a parametric model.