A system for adjusting and monitoring the pressures of printing rollers (3, 4) of printing stations arranged around a central drum of a flexographic printing machine, comprising: at least one reader which is adapted to be placed at the printing rollers (3, 4) of the printing machine directly behind the print in output from the central drum to detect the contrast of the print on the printing material wrapped around the central dram of the printing machine, said reader is constituted by a scanning head whose size is equal to the width of the printing material, and said reader is capable of reading over the entire printing width and of directly measuring the amount of the entire print on the printing material with respect to its background, said amount corresponding to said contrast; and a processing and control unit which is connected to said at least one reader and is adapted to determine and control, as a function of the contrast detected by said reader, the position of the printing rollers (3, 4) with respect to said central drum in order to achieve the desired print; and wherein said processing and control unit comprises a control section and a processing section that are adapted: to command performance of a sequence of stepwise movements, according to preset steps, of the printing plate roller with respect to the central drum or also of the anilox roller with respect to the printing plate roller, in order to make contact in printing at different printing pressures, to store for each movement of the printing plate roller data acquired regarding its position and the contrast measured by the reader; and to analyse and elaborate the acquired data and automatically calculate, the position and therefore the printing pressure of the printing plate roller with respect to the central drum in order to achieve the desired print. at least one reader which is adapted to be placed at the printing rollers (3, 4) of the printing machine directly behind the print in output from the central drum to detect the contrast of the print on the printing material wrapped around the central dram of the printing machine, said reader is constituted by a scanning head whose size is equal to the width of the printing material, and said reader is capable of reading over the entire printing width and of directly measuring the amount of the entire print on the printing material with respect to its background, said amount corresponding to said contrast; and a processing and control unit which is connected to said at least one reader and is adapted to determine and control, as a function of the contrast detected by said reader, the position of the printing rollers (3, 4) with respect to said central drum in order to achieve the desired print; and wherein said processing and control unit comprises a control section and a processing section that are adapted: to command performance of a sequence of stepwise movements, according to preset steps, of the printing plate roller with respect to the central drum or also of the anilox roller with respect to the printing plate roller, in order to make contact in printing at different printing pressures, to store for each movement of the printing plate roller data acquired regarding its position and the contrast measured by the reader; and to analyse and elaborate the acquired data and automatically calculate, the position and therefore the printing pressure of the printing plate roller with respect to the central drum in order to achieve the desired print. to command performance of a sequence of stepwise movements, according to preset steps, of the printing plate roller with respect to the central drum or also of the anilox roller with respect to the printing plate roller, in order to make contact in printing at different printing pressures, to store for each movement of the printing plate roller data acquired regarding its position and the contrast measured by the reader; and to analyse and elaborate the acquired data and automatically calculate, the position and therefore the printing pressure of the printing plate roller with respect to the central drum in order to achieve the desired print.