Religion
In reply to the discussion: Shroud of Turin [View all]edhopper
(33,575 posts)the Camera Obscure, had been used since ancient times. The use of it to actually produce a photo like picture, as opposed to only a projection, did not occur until the 19th Century.
You are proposing that an obscure artisan invented the photography process "out of whole cloth" and then produced this one surviving image. With no reoccurrence of anything like it for 800 years.
There is no evidence in any of the test for any of the compounds you mention and no evidence that such a process existed at that time.
Your theory is not physically impossible and doesn't fall into the category of the mystical mumbo jumbo believers say.
But there is really no evidence to support it, especially when other contemporary methods explain it as well.
You do provide a testable experiment to verify your theory. Unfortunately it probably won't ever be performed.