Why is it so hard to explain the image?
There are specific key characteristics of the image that any theory must account for:
1. The image is a photographic negative
2. There is a 3D property to the image – the further away a part of the body was from the cloth the fainter that part appears
3. The image is visible only in the very upper fibres of the cloth – it does not go all the way through to the back of the cloth
4. When standing close to the cloth the image is not visible – it is only visible when standing a few metres away from the cloth
5. The blood flows on the cloth have been shown to be 100% anatomically correct based on modern physiology
6. There are no pigments or dyes used on the cloth
7. The blood is human and contains extractable DNA samples
It is very hard to put together a theory that can satisfy all of the above items.