The aim of this paper is to propose a new strategy to both enhance the colorfulness of a color image and to improve its contrasts by using the full RGB color gamut. Colorfulness can be seen as a global perceptual attribute which is highly correlated to the average chroma. This new strategy consists to extend image color gamut by performing saturation increasing in the λSY color space. In order to analyse and to describe color image changes, we have chosen to represent color images according to their color point distribution in the xyY color space.