In an image processor, a color format converter converts a pixel, which is expressed in an RGB color space, into a converted pixel, which is expressed in an YUV color space. The return duct is provided, in the region of its mouth into the suction duct, with at least one nozzle device. Embodiments may also include a plurality of concentric annular elements of increasing circumference centered about the central axis and the central annular element, where each annular element is positioned around an annular element having a smaller circumference. Such a grating device may be used to grate material. In addition, the imaging apparatus stores the generic image data and the key image data in an identical storage medium in expressions distinguishable from each other.