Sixels is supported by more than one terminal implementation, while the example you posted only works in iTerm2 (and IIRC only accepts a filename as input, but

Sixels is supported by more than one terminal implementation, while the example you posted only works in iTerm2 (and IIRC only accepts a filename as input, but doesn't offer a way to send image data directly as a stream of characters through stdout). I would welcome a proper pixel graphics / framebuffer standard for terminals though.