Color Calibration for the Pressure Ulcer Image Acquired Under Differ- ent Illumination: A Key Step for Simple, Rapid and Quantitative Color Evaluation of the Human Skin Diseases Using a Digital Camera

To eliminate the color appearance variation of the images acquired under the various lighting conditions, we have developed a simple four colored chart (Skin chart) for the color calibration of the human skin images based on the features of the human skin color. The color calibration with the Skin chart worked better than that with a standard color chart. A conventionally obtained photo-image of the pressure ulcer (PU) in medical facilities can be translated into a standard photo-image taken in the standard lighting. The present method is more convenient compared with the previously reported systems using the commercially available color charts. Accordingly, the method successfully identified the involved areas from the healthy skin areas by the color image. The newly developed method is a useful tool for the color image acquisition using conventional digital cameras for the electronic medical recording systems and for the medical consulting network by the information communication technologies (ICTs). The developed color calibration method enables simple, easy, rapid, and less expensive record for the shapes of PUs and the quantitative color distribution of the widely involved areas. Thus, this system is expected as an evaluation tool for the topical therapies for PUs in future.