Transformations of digitized color images in perceptually-uniform CIELUV color space and their perceptual relevance were investigated. Chroma variation was chosen as the first step of a series of investigations into possible transformations (including lightness, hue-angle, chroma, etc.). To obtain the information about the perceptual consequences of the chosen transformations, perceptual image quality, naturalness, and colorfulness were measured by means of scaling. The results suggest that in general a more colorful image than the original one is preferred.