Having spent some time playing with colours in terminal, I wanted the ability to
upload an image and have the content mapped to the closest colour from the ANSI
terminal's 256 colour palette. Combined with the terminal preview mechanism I'd
created as part of my bash-ps1 project, I've shared this tool. The image is
never sent to the server as all the processing work is carried out in-browser by
JavaScript.
Feel free to fork this, you can also see it in action here.