text: A fiber is not necessarily colored for all its length, but, in the parts where it is, it has the property of being colored all around its cylindrical surface.
  Under the crossing threads of the weave, the image is not present.
  The discoloration seems caused by a kind of dehydrative oxidation process, which has discolored and chemically altered the surfaces of certain surface fibrils.
  The image of the Shroud is an areal density image, in the sense that the levels of darkness are not given by variations of the color, which instead is approximately constant all over the image, but by a variation of the number of yellowed fibers per unit area. Therefore, it can be considered a halftone image. Furthermore, there is no difference in terms of distribution of fiber coloration and maximum densities between the front and the rear of the image.
  While the blood images could have come from a contact mechanism, the body image could not. The mapping between body-only image densities and expected cloth–body distances is not consistent with the image having been formed by direct contact with a body, as it is present even when it does not seem possible for the cloth to be in contact with the body.
  Hypotheses on image origin