I built a pixelated, embossed version of Lichtenstein’s piece in Minecraft Classic. I used a 128x128x64 blocks private map on Aeries server.
I hung the picture in the sky, on top of the ‘map’ facing down, to be able to use the maximum size available of 128×128 blocks. It might not seem much of a resolution, but it is still nearly 16.5k blocks!
First, I created a special, custom colour palette in Photoshop, based on blocks of Minecraft. It contains 28 colours plus 1 for alpha channel. I resized the image and converted it to indexed-colour using this custom palette.
I completely replaced the polka-dots pattern as it was too fine and wouldn’t be visible with the little amount of pixels available.
Then I wrote a PHP script that converts the indexed bitmap to polar coordinates: x, y, z. Colour attribute is specified as block name. The PHP script generates a file with a list of simple commands to tell Minecraft where to place a blocks and which material e. g. /place obsidian 0 0 0.
After that I created yet another bitmap for depth, just to add it a bit of a 3D touch.
And finally used an AppleScript to automate sending nearly 50.000 lines via Java Applet loader that runs the game.
Here are the source files: Image-to-Mincraft.zip.
Classic has been discontinued, but a browser-based remake came out in 2019. Source: Wikipedia