Following on from the first attempt. I decided to go back to basics and see if any heat shielding could create a pattern on toast.
The first pattern, look really good.
Alas is does not produce any good or noticeable pattern burnt on the the bread. (I skipped the photo of a slice of bread).
Time for some more simple patterns.
Results are a little better, but still the resolution is very low.
The wavelength appears to be high, although this would be wrong. Looks like the heat protection, or insulator is not much good. Rather than thinking about Infra-red and heat http://en.wikipedia.org/wiki/Infrared#Heat, I need to be thinking about isolating.
Note commands used in this post:
$ ls content/images/second-attempt/* -l | cut -d' ' -f9 $ mogrify *.jpg -resize 600x *.jpg