I'd like to have a noise 'glimmering' effect that I have seen on 'Radio Student' website. Here's my screen recording of it (in the video below).
My observations; I added them after Jens replied below.
a) what is changing it's not the hue (i.e. color 'shade') component, but the darkness/lightness (i.e. 'value') component of each tiny group of pixels;
b) what is changing are groups of pixels (i.e. not random single pixels);
c) each of those groups stays at its location.
Using lots of clones (of a little circle), with the (original) big image being PASTed ON them and then applying the block that changes the value (i.e. darkness/lightness) of each clone's costume (in a loop with a different timing for each clone)?