HemaApp Illumination (IMAGE) University of Washington Caption The smartphone's camera flash illuminates a patient's finger. HemaApp relies on the fact that different blood compounds such as hemoglobin produce variances in color at different concentrations. Credit Dennis Wise/University of Washington Usage Restrictions With credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.