1. A vertical detail enhancer comprising: a source of interlaced luminance signals; a producer of interstitial luminance signals responsive to said interlaced luminance signals; means for modifying transitions of said interlaced and interstitial luminance signals to produce vertical detail enhanced interlaced and interstitial luminance signals having only overshoot for transitions of a given sense and having only undershoot for transitions of the opposite of said given sense; and means for sequencing said vertical detail enhanced interlaced and interstitial luminance signals to create a luminance signal representing a progressively scanned image.