Plagiarism does apply to images cause it can be stolen, but it's difficult to prove, probably the reason why it is not strictly enforced.
On bitcointalk, even if you prove plagiarism, and plagiairst admits it, he still won't get banned, like in this case
Shouldn't this be treated as an obvious plagiarism case?. Can;t be more blatant that that, with all the evidence needed, yet user avoided ban. Yet, if he copied some insignificant sentence, he would end up getting banned. Doesn't make much sense to me, but it is what it is.
I have seen members do that a lot. They upload an image to imgur to take advantage of imgur's quick resizing options. As you know, Bitcointalk doesn't have resizing buttons available when you create new posts. You would need to know the codes by heart to resize your images properly.
Isn't image resizing on bitcointalk pretty simple and straightforward? You just add either width or height number in that "[Img width/height=xyz]" bracket and thats about it? Like 2 secs work.