Mario (website = Sindonology) writes in a comment:
I think that the presence of 3D data in the Shroud image is simple and can be mathematically explained in a simple way. I also think that the anaglyph is a very simple transformation of that data into a 3D encoding that can be visually perceived. That very simple process leaves no doubt that 3D data exist in the Shroud image. And there is no subjectivity involved as far as this process is completely independent of the Shroud and has been used to generate millions of other anaglyphs. Sorry to repeat this reference, but for a short presentation of how such 3D data is encoded and an anaglyph version of the entire Shroud image can be generated, please see:
In a few words, the composite software simply (based on a linear transformation) shift horizontally, based on the luminosity of the pixels, some of the pixels of the Enrie photograph and then combined them with the original photograph using two different colors, one for the original image and a different color for the shifted pixels. It is therefore a very simple process that can be described by a simple linear transformation of pixel locations. It can’t get much simpler.
The Shroud Scope has the full Enrie photograph transformed as an anaglyph where you can zoom-in and -out (back and front of the man of the Shroud). For example, please see (you will need color filtered glasses):
(Again, absolutely no artistic or subjective transformation was applied to generate that image, but only the transformation described in the previous reference was applied.)
Notice the various details of the realistic 3D image, for example the belly, the front feet where we have a perception of the tip (toes?) of the feet, and of course the various 3D details of the face. The back is also quite interesting in terms of 3D realistic representation.
What is not complete clear yet, is the effect of the cloth wrapping the body versus this 3D data. But what appears almost certain to me is that the image was formed while it loosely wrapped a 3D form, and clues to that are numerous, such as parts of hair appears at the same level as the cheeks which means that the cloth was very closed to the hair when the image was formed. But a complete clarification of the relation of the wrapping vs the cloth body distance can be done by doing a computer simulation. Not very complex to do, but quite tedious to do in details.