General purpose filters include amplitude, phase and group delay equalization to improve pulse and bar response. Smooth slower roll off reduces ringing. Can be used as in any Video bandwidth limiting application. Also used as anti aliasing pre filters in analog to digital conversion applications or as post aliasing filters with the addition of sin x/x correction. For many years amplitude, delay and phase corrected filters have found applications in television broadcasting, cable transmission, direct satellite transmission, analog and digital image processing, analog to digital conversion and computer graphics. Allen Avionics offers four basic shape factors or stopband ratios in their range of video.