A method and a device for correcting the phase between the pixel clock of a graphics card and the sampling clock of a flat-panel display with an analog interface in a system including a flat-panel display, graphics card, and computer. Automatic adjustment of the phase is performed repeatedly. In the process, the rising edge of a video pulse of a sufficiently bright image spot in the first image column close to the back-porch region is determined. The falling edge of a video pulse is determined at a sufficiently bright image spot in the last image column close to the front-porch region, and the phase is adjusted such that the sampling instant is situated approximately at the midpoint between the rising and falling edges of a video pulse.