A system for registering a printing press, said printing press including a plurality of printing stations (162 1 -162 4) each for printing a respective color image on a web, each said printing stations (162 1 -162 4) being associated with a respective different color, at least two of said printing stations (162 1 -162 4) being un-registered, said system comprising: an imager acquiring an image of a common area of said web, the driver side of said acquired image including at least a portion of at least one color image associated with at least one respective un-registered printing station (162 1 -162 4) and the operator side of said acquired image including at least a portion of at least one other color image associated with at least a respective other un-registered printing station (162 1- 162 4); and a processor, coupled with said imager, registering said at least two un-registered printing stations (162 1 -162 4), by registering said at least a portion of-said at least one color image (122, 128) with at least a portion of said at least one other color image (124, 126) by registering at least two monochrome images (230, 232), each monochrome image (230, 232) corresponding to a color image (122, 124, 126, 128) printed on said common area, each monochrome image (230, 232) being determined according to the location of each pixel of said acquired image in a color separation space, characterised in that said location of each pixel in said color separation space is determined according to the projected location of each pixel of said acquired image on a color projection plane, said color projection plane being determined according to the coordinates of the color associated with each said un-registered printing stations (162 1 -162 4) and the coordinates of the color of said web in a selected color: space. an imager acquiring an image of a common area of said web, the driver side of said acquired image including at least a portion of at least one color image associated with at least one respective un-registered printing station (162 1 -162 4) and the operator side of said acquired image including at least a portion of at least one other color image associated with at least a respective other un-registered printing station (162 1- 162 4); and a processor, coupled with said imager, registering said at least two un-registered printing stations (162 1 -162 4), by registering said at least a portion of-said at least one color image (122, 128) with at least a portion of said at least one other color image (124, 126) by registering at least two monochrome images (230, 232), each monochrome image (230, 232) corresponding to a color image (122, 124, 126, 128) printed on said common area, each monochrome image (230, 232) being determined according to the location of each pixel of said acquired image in a color separation space, characterised in that said location of each pixel in said color separation space is determined according to the projected location of each pixel of said acquired image on a color projection plane, said color projection plane being determined according to the coordinates of the color associated with each said un-registered printing stations (162 1 -162 4) and the coordinates of the color of said web in a selected color: space.