The inverse terrain map data is consistent with the penetration of 200 nm ultraviolet (UV) light, also called deep UV (DUV) and vacuum UV (VUV), most of it is gone after only 4 to 6 inches of air.
IF whatever transition or divine intervention the body of the person in the shroud went through was accompanied by an intense burst of DUV, the energy delivered to the linen would 'map' the distance between the skin and the linen.
Where the linen was closest to the body it would have its chemical structure disrupted, but because DUV is so strongly absorbed, only the surface of the side of the fibers facing the body would be damaged. A bit further away, less DUV gets through the air, and there is less damage. A foot away, no DUV survives and the linen is undamaged.
The damaged areas gradually brown on exposure to air developing an image.
As an agnostic, I provide this as a plausible photochemical mechanism for the image being formed. That's the how. The why is beyond my ken. *sigh*
I always thought the image looked like a Viking.
Very interesting hypothesis. I like it. Only one problem is that there are no light, UV, or otherwise, artifacting, such as shadowing, on the Shroud. There are some other enigmatic problems that need explanations. For example, under computer enhancement. the bones shadowing inside the hands are faintly visible, as are the teeth shadowing behind the lips, including even fainter the tooth roots. There are just so many enigma’s in the Shroud the more we learn, the more mysteries we find. Nothing proposed as an image creation schema seems to cover all possible observed phenomena on the Shroud.
+1 for mechanism.