Are these colorful stickers or computer imprinting?

The first are two Peanuts medals. Are they modified by color imprinting?

The secnd and third coins are made by Japan Mint. Are they modified by colorful stickers or computer imprinting?

What do you mean by “computer” imprinting? 

Japanese coins are either colourised by pad-printing or through micro surface structures that break the light and lead to a rainbow shimmer effect (you examples being the former).

I made a mistake. It should be the colorful printing of coin controlled by the computer. That's the pad printing you mentioned.