  Unitary rotations of polychromatic images on finite two-dimensional
pixellated screens provide invertibility, group composition, and thus
conservation of information. Rotations have been applied on monochromatic image
data sets, where we now examine closer the Gibbs-like oscillations that appear
due to discrete "discontinuities" of the input images under unitary
transformations. Extended to three-color images we examine here the display of
color at the pixels where, due to the oscillations, some pixel color values may
fall outside their required common numerical range [0, 1], between absence and
saturation of the red, green, and blue formant color images.
