The code is here: https://github.com/eliasdaler/crten
You can check out how it works, if you’re using Ebiten. Otherwise, you can use it as a standalone app for static images like this:
crten INPUT_FILE - display INPUT_FILE with CRT effect.
crten -i INPUT_FILE [-c CONFIG_FILE] OUTPUT_FILE - renders INPUT_FILE image with CRT effect to OUTPUT_FILE and closes the window.