A device for correcting the phase of a vertically distorted digital picture receives picture data and a vertical phase correction signal, and assigns lines of the digital picture to a first half picture and to a second half picture. The lines of the second half picture are phase corrected with respect to the first half picture and the first and second half pictures are displayed sequentially. The phase correction is determined in response an increment signal that describes the change of an imaging factor in the veritcal direction of the digital picture on a line-by-line basis and a picture position signal indicative of whether the first half picture or the second half picture is being output.