Block Posters is an online tool you can use to generate posters from any image.
The posters are made up of individual A4 sheets either positioned landscape or portrait, created in 3 easy steps. Larger images will produce less blocky images, but blocky images do actually look great when they’re put up on the wall.
Depending on the look you want to go for, you can make it look like a mosaic or just have one big seamless image. This is great way to have nice looking posters and not spend a lot of money (Makes me think of 8bit art on a larger scale).