aliasing

"Aliasing refers to defects or distortion in a television picture. In analog video, aliasing is most often caused by interference between two frequencies such as the luminance and chrominance. In digital video, aliasing is caused by insufficient sampling or poor filtering of the digital video. Defects are typically seen as jagged edges on diagonal lines and twinkling or brightening of picture detail. Anti-aliasing refers to technologies used to counter this. See also anti-aliasing, chrominance signal, and luminance signal."