1. A method for processing video data, comprising the steps of: (a) entering each input frame constituting the video data; and (b) judging whether each input frame entered at the step (a) is a telop character displaying frame in which telop characters are displayed or not, according to edge pairs detected from each input frame by detecting each two adjacent edge pixels for which intensity gradient directions are opposite on some scanning line used in judging an intensity gradient direction at each edge pixel and for which an intensity difference between said two adjacent edge pixels is within a prescribed range as one edge pair, edge pixels being pixels at which an intensity value locally changes by at least a prescribed amount with respect to a neighboring pixel among a plurality of pixels constituting each input frame.