The article considers the problems of developing and improving theoretical methods of synthesizing the monochrome image from the multirange one, in cases when the transmitted images refer to the range different from the visible one. The method of automatic synthesizing the monochrome image has been developed. It applies varied palette, derived from the Poisson equation. Numerical results are given and compared with existing means. Advantages and disadvantages of the method are analyzed.  Ways of eliminating the discovered defects are proposed.