Now I made a manual adjustment to color balance, so that the picture is "warmer". What does that mean? It means red is dominant, not blue. Both pieces of paper are now giving off more red than blue or green.

Does it look fake? Not to me. So which is real, blue or red? They're both real. Do what you want. use a blue IBL and an orange sun to get a warmer render. Use white for both for a neutral render. Or use blue IBL and a white sun to give what is commonly produced by cameras that are set to "auto".

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)