I made a little script that converts a picture into a PICO-8 cartridge. Here how it works:
1. Install PHP and its GD library. Works best on Linux and OS X, but can also work on Windows.
2. Download this pic2p8.php script and run it like this:
php pic2p8.php mypic.jpg3. Copy the output into a new file with a .p8 extension into your cartridge folder. (Type folder in the PICO-8 prompt, or for you Linux users do this:)
php pic2p8.php mypic.jpg > ~/.lexaloffle/pico-8/carts/mypic.p84. Now you can load the cart and run it in PICO-8 already as it have some simple code to show it.
If you're not satisfied with the result you can always try GIMP:
1. Download PICO-8.gpl and put it in GIMP's palette directory.
2. Create or resize an existing picture in 128x128 and modify it however you like.
3. Go to Image > Mode > Indexed colors > Use a custom palette > PICO-8, uncheck Remove unused colors from palette, click OK.
4. Now export the resulting picture and run it through the above script.
Now that you have a full-screen picture, you can do interesting stuff with it, play some music on it or whatever... Have fun!