A method of estimating an amount of a substance in a bodily fluid from the color of a tissue surface of a subject includes capturing an image including at least a portion-of-interest of the subject and at least a reference portion of a color reference, the image being a digital image of pixels of at...http://www.google.ca/patents/US7711403?utm_source=gb-gplus-sharePatent US7711403 - Non-invasive determination of blood components
