I have always used the word "plaintext" to mean content that has not been subject to encryption or hashing, whether it is text, arbitrary bytes (including multi

I have always used the word "plaintext" to mean content that has not been subject to encryption or hashing, whether it is text, arbitrary bytes (including multimedia formats), or even abstract ideas which can be somehow subject to a cipher. But these terms are certainly used different in different situations by different people. But yeah, images and/or video can still be "the plaintext" in the parlance to which I'm accustomed.