In order to avoid rounding errors as a result of restricted accuracy of the processing unit in a video processing arrangement, a comparison is carried out between processed image data and unprocessed image data. For this purpose, the unprocessed image data is buffer-stored in a memory and is supplied together with the processed image data to a comparator, which compares the difference between the processed image data and the unprocessed image data with a threshold value. Either the processed image data or the unprocessed image data is produced at the output of the arrangement, by means of a multiplexer, as a function of the result of the comparison. A rounding element between the processing unit and the multiplexer rounds the processed image data before it is emitted, if the processing stage has not itself carried out a rounding process.