Don't worry, I'm not selling anything. Just giving a shoutout to one of my open-source side projects:
I created a programming language for beginners and am looking for people to test it out. If you have a spare moment (particularly if you haven't programmed before) and you're interested in making 2D games, please check it out.
MSPaint Tutorial - Adding a Noise/Pixelation Effect
Ever wanted to create pixelated noise in MSPaint? Probably not. But too bad! I'm teaching you anyway!
Select the region of the picture you wish to pixelate...
Now, in the Stretch and Skew menu (Ctrl + W), skew it horizontally by 10 degrees and vertically by -10 degrees.
So now it'll look like this...
Repeat this process. After about 4 times, it'll look like this...
Keep repeating it. This is what it looks like after about 10 times.
It has almost neared a complete 90 degree rotation. So, let's do a "clean" rotate to restore it somewhat to where it was originally. Rotate it 270 degrees in the Flip and Rotate menu (Ctrl + R).
Now let's fudge it back to a square with the stretch and skew menu. There's no easy way to come up with these numbers without some trigonmetry. I'm just eyeballing, here...
Close enough for government work.
If you want to make it less grainy, then use increments larger than 10 to rotate it (Less iterations == less distortion). Or, conversely, you can go half way to 45 degrees and then use the 45 degree rotation method to reorient it. If you want to make it more pixelated, then use smaller increments.