What should we think about this material from The Shroud: A Critical Summary of Observations, Data and Hypotheses, by Robert W. Siefker and Daniel S. Spicer.
Table I, Item 6.0:
The body image has a resolution of 4.9±0.5mm but no well-defined contours. This means that that human details such as the nose, lips, and beard are clearly defined, but that the body image seems to disappear if someone looks at it from a distance closer than about 1m.
The combination of the low contrast between the image and the background and the lack of defined borders makes the image essentially disappear when viewed from a range closer than 1.5 meters. An artist attempting to paint the image would need an assistant to indicate where to paint or an exceedingly long handle on the brush or applicator, scenarios inconsistent with the image’s high resolution.
Unless the image has faded? Or if some other artistic method is used. The fact that the image seems to disappear beyond a meter or so is interesting, but what, if anything, does it really mean?