We present the results of experiments in which we manipulated color images in the CIELAB space by first applying a scaling factor on chroma (C*). After this we applied a gamma transformation (an exponent relating the input to the output) to the luminance (Y) in XYZ space, while keeping the chromaticity values (x, y) constant. The aim of the experiments was to test the subjective preference for a particular gamma and chroma scaling factor. Two natural images (standard ISO images) were transformed with 4 different values of gamma and 4 different scaling factors for chroma. The images were viewed on a CRT monitor. We found that the preference depends on the gamma, on the chroma scaling factor and on both variables combined. However, increasing or decreasing one or both variables does not improve the preference for the images that are used. The results were not significantly different for the two different images.