Brightness contrast enhancement technology, algorithm, and its program realization

Abstract

Information technology for initially latent graphic information visual acquisition is considered. Concrete technique operates by means of picture fragments contrast enhancement up to overcoming of the threshold of human eye's contrast sensitivity. Only one partial – brightness contrast is implied hereinafter. Mathematical formalization for the brightness control process with the help of regular tools <Brightness> and <Contrast> of modern raster graphics software is actualized. Conversion of brightness, hue and saturation of color by these tools is investigated. Though the range of permissible effects on brightness is wide enough, errors associated with chromatic color characteristics are shown to be unacceptable. Existence of such errors predetermines the need to develop new software. A way to correct the errors of defective algorithm is proposed. The principle of RGB coordinates proportional transformation has been introduced, allowing to avoid any chromatic contrasts distortions while controlling brightness. Method and attributes of brightness control aimed on brightness contrast variation are laid out. Basic elements of the algorithm structure – procedures, operations and conditional branches – are described in details. Scheme of the brightness contrast enhancement algorithm is given in a simplified form. Basic information about the program is provided, its development, technical data, support software, system requirements. The results of testing the program for model images are carefully specified. Program approbation was carried out successfully – significant increase of visual information content of the images accompanied by the absence of any graphic artifacts was received. All described and illustrated examples of probation of new software product on natural images are being discussed in comparison with the results obtained by means of Adobe production most common in the world today. Some recommendations on the image contrast analysis in the field of expert activities are formulated and hot points for further work to improve the contrast-enhancement technology are outlined.