Abstract: A method of printing a substrate with a matrix printer provided with at least two image-forming elements, including moving the elements with respect to the substrate and activating the elements image-wise in order to provide pixels with image-forming material. In the event of breakdown of an image-forming element so that at least one pixel cannot be provided with image-forming material, the information of that pixel is transferred to an addressable position in the vicinity of the associated pixel.

Abstract: A method of reproducing images formed from binary values of basic pixels arranged in a raster, with an electrophotographic printing unit having an electrically chargeable photo-conductive medium, a selectively activatable light source to discharge of the medium and a developing unit for developing the said medium with toner powder. The method processes the digital image data to compensate for properties of the printing unit by: generating two sub-pixels for each basic pixel, where a first sub-pixel always corresponds in value to the value of the associated basic pixel and a second sub-pixel has a value that depends upon the value of the associated basic pixel and upon the values of basic pixels in a predetermined area around the associated basic pixel; and generating control signals to activate the light source in accordance with each of the generated sub-pixels. Initially, the second pixel is given the same value as that of the associated basic pixel.