Image –› Code

So,  I'm curious about how things like the 4chan.hta were made. If you're not familiar, it's basically an image file that when saved as an hta epuld execute some entertaining code. The only way I could think it'd work is if it the text was converted to binary and then that was used for the image. So any ideas?

O-okay, I guess.
Of course, by that I mean I'll be here shitting up your threads for a while.