Ray Schneider has put together some useful charts on the subject in
The Shroud of Turin an Enduring Mystery – Part 4: Skeptics & Image Formation 
(Charts 14, 16-18 deal with resolution).

imageIn snippets from comments, Hugh Farey has raised some good questions about image resolution. 

To Louis, he wrote:

Can I ask for some opinion about ‘high resolution’ we keep hearing about. The resolution is not at all high. The resolution is poor. The fat that one smudge can be seen as the edge of the lower lip does not justify the complete absence of any nipples, fingernails, navel and so on, all of which would be expected from an image of any good resolution.

And in response to a comment by Max, Hugh wrote:

I wish I knew what people mean by a resolution of 5mm. Grab a pencil and draw the outline of the arms. How precise is it? 30mm, I reckon. The fingers and face are a bit better, but a contact image precise to an accuracy of 5mm is not good resolution, it’s poor. One of the arguments against the Shroud being some kind of bas relief rubbing is just that – its resolution is so poor.

Max had said:

The optical high resolution of the details of the TS body images –at least as good as 0.5 cm (see L. A. Schwalbe, R. N. Rogers, “Physics and chemistry of the Shroud of Turin, a summary of the 1978 investigation,” Analytica Chimica Acta 135, 3-49, 1982 and J. P. Jackson, E. J. Jumper, W. R. Ercoline, “Correlation of image intensity on the Turin Shroud with the 3-D structure of a human body shape,” Appl. Opt. 23, 2244-2270, 1984) or even approaching 0.1 to 0.2 cm (see V. D. Miller and S. F. Pellicori, “Ultraviolet fluorescence photography of the Shroud of Turin”, Journal of Biological Photography, 49, 71-85,1981)– suggests a contact-and-gradual-loss-of- contact mechanism of transfer to account for the integrity of blood clots of which optical high resolution of their details is as good as 0.04-0.05 cm that is ten times higher than the body image details).

Optically speaking, what do you consider is the minimum for “high-res”?

Hugh wrote back to Max:

Yes that’s what they all say, and perhaps I misunderstand them. Can we detect collarbones or the Shroud image? Ribs? Kneecaps? You don’t need a very high resolution to see these clearly on images of people, and the Shroud shows none of them. I don’t know how the resolution of an image of a body should be quantified, but I do know that the Shroud isn’t very very high, regardless of what Schwalbe and friends think, unless, as I say, I misunderstand what they mean by a resolution of 5mm.

and later added:

You are still explaining why the resolution is poor rather than substantiating the opinion that it is good. Prof. Fanti did indeed say that the edge of the lower lip of the image was well defined, and I agree with him. The rest of the face is less so, and the rest of the body a mere blur. optically speaking a well defined Shroud image would be one around which it would be possible for different people independently to draw outlines of various features (e.g. arms, legs, eyes, fingers) and when superimposed they should not differ by more than a millimetre or so. I said that before. That’s my answer.

Ray Schneider has put together some useful charts on the subject in The Shroud of Turin an Enduring Mystery – Part 4: Skeptics & Image Formation (Charts 14, 16-18 deal with resolution).