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

Graphic information carried by hue contrast is actualized, mathematical description specificity of hue as the basic colour characteristic is investigated, theoretical bases of hue contrast control are stated, original algorithm and program for images hue contrast control are described, resolution of the offered method is experimentally estimated, scope of the created software product possible applications is outlined, efficiency of its application in expert problems is shown.

Keywords: graphic information, hue contrast, contrast control, algorithm and program realization, latent images