The ability to change brightness contrast of images with the help of some graphic packages’ tool is studied. In parallel the influence of this tool on hue and saturation of forming the image pixels is investigated. It is shown that tool as a whole is of little use for brightness contrast informative control, because in a number of packages it cannot provide brightness contrast gain, in others - does not keep hue and in all - deforms a saturation that threatens with loss of the graphic information transferred by saturation contrasts. Corresponding artifacts are considered and discussed.

Keywords: nonlinear brightness control, brightness contrast, colour hue and saturation, graphic information integrity, artifacts