An image scanner in which an original is scanned by a trilinear CCD array, i.e. the original is scanned line by line, three lines at the time, one line for each color. Thus, at a specific time "only" the area of the original that is scanned by the trilinear CCD array at that time has to be positioned in focus of the imaging means of the image scanner while the remaining part of the original may be positioned anywhere and may adopt any suitable form. Thus, there is no need for all parts of the original to be kept flat and planar as required in known flat bed scanners. The original is kept flat and straight along a line to be scanned by imparting a substantially cylindrical shape, such as a circular cylindrical shape, to at least part of the original. The original is scanned along lines that are substantially parallel to the generatrix of the cylindrical part of the original. Thus, the fact that all parts of the original are not scanned simultaneously is exploited to simplify the positioning of the original in the image scanner.