Change of Colour with Intencity?

Considering the sheer volume of information in the original post, I believe you have done very well at picking away the non-essential meaningless data, leaving only the bone or true structure of the question.

Not sure it helps to OP, but I'll give ya a GA.

You should have given it a SA.

Sarcastic Answer.

But, I didn't insult anybody.

A little study on blacksmithing might also help, wherein you can tell metal temperature fairly closely by its color (dull red, cherry red, straw yellow, etc.) And similarly for flame temperatures. Perhaps the OP could clarify?

Or psychology: rosy cheeks, pink blush, seeing red, enraged purple (with suitable emoticons)