Nonlinear temporal filter for television picture noise reduction
Tim J. Dennis · IEE Proceedings G (Electronic Circuits and Systems) · 1980
A conventional recursive interframe lowpass filter for 625 line 5.5 MHz monochrome television is modified so that its attenuation of frame differences is instantaneously dependent on their amplitude. This results in improved rendition of motion when compared with the original design. Performance is assessed by objective measurement of noise attenuation for a range of input noise levels and nonlinear characteristics, and by subjective opinion tests on pictures containing noise and movement.