A New Modulation Method To Eliminate The Dynamic False Contour In LED Display

LED displays modulate grayscales through gated pulse width modulationtechnology, which realizes various grayscales by the combination of different binarysub-fields. However, the dispersed binary sub-fields will lead to the dispersion of thebrightness of light emitting diode in time scale. Due to the smooth eye trackingcharacteristic of human eyes, the brightness of different pixels is integrated whenmoving images are played, which results in the appearance of dynamic false contour.In order to eliminate the dynamic false contour, we proposed a novel LED displaygray modulation scheme, which divided the whole modulation period into two parts:integer bit modulation and decimal bit modulation. No weight was employed during theinteger bit modulation while the decimal bit modulation was realized at fixed location.Through this method, the interference between different pixels was effectively inhibited.According to the realization methods of this technology, we optimized our scheme fromthe aspects of the effects and difficulties in the realization of grayscale, finally,concentrated gated pulse width modulation was proposed.Simulation and experimental results showed that the concentrated gated pulsewidth modulation can eliminate the dynamic false contour while maintaining a highrefresh rate and rich gradation bits. When the new modulation was used, the value ofdynamic false contour reduced from0.8to0.2while the value of the PSNR and thestructural similarity to the standard image increased from about20to about45andapproximately0.5to0.9, respectively. Therefore, concentrated gated pulse widthmodulation can effectively eliminate the dynamic false contour，and is simple to realize.Furthermore, the corresponding requirements for hardware is low.