The invention relates to a method and to a device for scanning an image, wherein a source image is detected by means of a colour sensor. The colour sensor comprises several line arrays which are formed, respectively, to detect a specific colour. Colour separations are generated by means of said line arrays. According to the invention, separate FIR partial filters are applied to the colour separations without having to mix said colour separations prior to a complete colour image. Mixing of the image pixels occurs automatically during filtering. As a result, the several line arrays can scan the image points of the source image simultaneously and said image points can be formed in real time on image pixels of a target image.