There is no Quranic injunction against images, whether of Muhammad or anyone else. When it spread into the Levant, Islam came into contact with a version of Christianity that was militantly iconoclastic. As a result some Muslim theologians, at a time when Islam still had an organic theology, issued "fatwas" against any depiction of the Godhead. That position was further buttressed by the fact that Islam acknowledges the Jewish Ten Commandments -- which include a ban on depicting God -- as part of its heritage. The issue has never been decided one way or another, and the claim that a ban on images is "an absolute principle of Islam" is purely political. Islam has only one absolute principle: the Oneness of God. Trying to invent other absolutes is, from the point of view of Islamic theology, nothing but sherk, i.e., the bestowal on the Many of the attributes of the One.
The claim that the ban on depicting Muhammad and other prophets is an absolute principle of Islam is also refuted by history. Many portraits of Muhammad have been drawn by Muslim artists, often commissioned by Muslim rulers. There is no space here to provide an exhaustive list, but these are some of the most famous: ...
RTWT. Don't miss what he says about Islam and humor, and the prinicple of "limits and proportions". And remember what Omar said, "we here in the Middle East have tonnes of jokes about Allah, the prophets and the angels that are way more offensive, funny and obscene than those poorly-made cartoons, yet no one ever got shot for telling one of those jokes or at least we had never seen rallies and protests against those infidel joke-tellers."