The invention relates to a method and a device for reducing the effect of a loss of information during transmission at compressed band width, particularly during transmission at compressed band width of a PCM-signal. Each of the serially generated PCM-words indicates the light intensity in picture elements that are serially scanned in a TV-frame, the number of transmitted PCMwords in each TV-frame being less than the number of generated PCM-words. According to the invention the effect of the loss of picture information is reduced in such a manner that when band width comprsssion is made TV-line by TV-line the loss will alternately occur on the left and right edges of the TV-lines on the screen viewed downwards in consecutive order and when band width compression is made TV-field by TV-field the loss will alternately occur on the upper and lower edges of the screen, the loss of picture information only appearing as a lesser degree of resolution along the respective edges of the screen.