Love it or hate it (I’m in the later group) we can all agree that Lichtenstein was a lightning rod for IP issues.
Note that, in my professional opinion, these pieces do not satisfy the transformative quality test. But in the US, well-educated, white artists — who can afford expensive attorneys, get to make arguments like these:
“Comparing the source for Whaam! with the finished painting banishes the hoary idea that Lichtenstein profited on the back of the creativity of others. Lichtenstein transformed Novick’s artwork in a number of subtle but crucial ways. In general, he wanted to simplify and unify the image, to give it more clarity as a coherent work of art. For this reason, he removed two extra fighter jets to the right of the original panel. He also got rid of the lump of dark shadow representing a mountainside that was an ugly compositional mistake to the left of Novick’s picture. The result is that the two panels of Whaam! feel much more evenly balanced, producing a satisfying and well-structured visual effect.
While Novick’s explosion is a measly, scratchy little thing slipping out of frame, Lichtenstein’s self-possessed fireball unfurls like a blooming flower. Lichtenstein changed the colour of the letters spelling out “WHAAM!” from red to yellow, so that yellow would become another means of yoking everything together. As a result, the eye is cleverly led from the yellow of the speech bubble above the jet through the onomatopoeic sound effect to the explosion itself and back round to the horizontal vapour trail left behind by the missile.”