After effects mosaic plug-in is a bit tricky because of its controls. The plugin let you to choose an amount of horizontal blocks and an amount for vertical blocks. So when you try to have a square pixels grid to achieve a pixelated effect in after effects you’ll be likely to waste some minutes to find the right value. Furthermore if you want to add a grid in overlay it will start to become a nightmare.
I developed a preset to make things easier. Using the layer size it calculates the right amount of horizontal and vertical blocks to maintain the square ratio of the “pixels”. It handle also the size of an optional overlay grid to match the mosaic effects, and the speed of the animation/footage.
These are some looks that you can achieve with it:
As you may be able to see it might be useful also to simulate a macro lens on a screen.
And these are some renders with different footages and different parameters changing resolution, animation speed and gap size:
The preset is available for download. Actually the download contains two preset: the first one is to pixelate footage, just apply it to a footage layer or to a precomposed animation; the second one is to generate random pixels, drag it over any kind of layer. And have a play with its controls. That’s it.
I added some controls to make easier to find the main parameters but if you want to change other things, like colours or blending mode of the grid, I’m sure you will find it. In the effects control window obviously ;)