A circuit that converts the resolution of a video signal to a resolution that is higher or lower. For example, an HDTV set can increase (scale up/upconvert) the standard 480-line resolution from a DVD or TV channel to a 720 or 1080-line resolution by filling in the missing lines via software. Although this may enhance the image, it is not turning it into true high-definition content, which must have a minimum of 720 lines of resolution. Conversely, the image scaler in an HDTV set that displays only 720 lines of resolution (720p) can reduce (scale down/downconvert) a 1080-line HD signal to fit the screen's native 720 lines. See HDTV and LVDS.