Preserving hue is an important issue for color image processing. In order to preserve hue, color image processing is often carried out in HSI or HSV color space which is converted from RGB color space. Transforming from RGB color space to another color space and processing in this space usually generate the gamut problem. If color image processing with hue preserving is performed in RGB color space, the gamut problem is solved. Two hue preserving techniques, namely, scaling and shifting, for the processing intensity and saturation components in RGB color space are clearly indicated.
In this talk, we introduce some hue preserving methods in RGB color space without gamut problem based on these two concepts. Eventually, we introduce an intensity processing method while preserving hue & saturation and a saturation processing method while preserving hue & intensity. Arbitrary gray-scale transform methods can be applied to both the intensity component and the saturation component. Two processing methods are completely independent. Therefore, two methods are easily combined by applying two processing methods in succession. The combination method realizes the hue-preserving color image processing with a high arbitrariness without gamut problem. Furthermore, the concrete enhancement algorithm by using S-type transformation based on the combination method is introduced.
Akira Tagushi received the B.E., M.E. and Dr. Eng. Degrees in electrical engineering from Keio University, Yokohama, in 1984, 1986, 1989 respectively. In 1989, he joined Musashi Institute Technology (the old name of Tokyo City University). He is currently a Professor at the Department of Computer Science, Tokyo City University. From 1993 to 1994 he spent one year at the Signal Processing Laboratory, Tampere University of Technology, Finland as a visiting Researcher. His research interests are in the areas of digital image processing including nonlinear signal processing and color image processing. He served General Chair for IEEE ISPACS 2013. He is currently a Vice Chair of International Steering Committee of ISPACS. He is a senior member of IEEE and a fellow of IEICE.