Plot of Square-wave-function whos frequency increases to the right (vertical Lines of the graph were ommittet for clearity). For comparison the convolution of the same square wave function with a Gaussian is plotted in green. You clearly see that the amplidute of green function is decreasing to the right until no sinal is visable on the right end anymore. Thus you can see that convolution filters out the higher frequency components of the signal and there is no signal left at the high frequency end.
Own work
Dirk Hünniger