Abstract: An improvement in the measuring elements of closed circuit systems for controlling-correcting printing in offset printing machines is provided. The values of measurements are amplified, analogically commutated, converted from analog to digital form, and then microprocessed so as to be compared with standard values established in a memory program provided for each one of the valves controlling the printers block of each one of the printing bodies. A reading is taken decomposed into three variables, each one of which corresponds to one of the three basic colors of the visible spectrum in which the light from the colored stain is diffracted by means of a ROWLAND diffraction grating in which there is reflected the light from optical fibers arranged at 45.degree. angles with respect to the printing paper, and which direct a beam of light on the colored stain.

Abstract: A new machine for printing different colors simultaneously by the offset method, includes a single sectored cylinder which acts upon a single rubber printing cylinder and which bears several sectors mounted upon its surface. The sectors are fixed to it by conventional centering and adjusting means, the machine being at the same time provided with individual fountains and rollers for ink and water, one for each of the sectors. Each of the sectors is a receiver of a single color. The fountains and rollers of ink and water are provided with retractable means, in such a manner that each of the fountain and roller arrangements dedicated to a given color operates at a determined time on one and only one sector, the sector involved corresponding to the given color.