By popular demand, here’s the result of using my flour imprinting model on a real human face, well, my own…
We’ll let the photos tell their own story, postponing the discussion for Comments (mainly), though as before, I might tack additions onto this posting later in the light of comments, further thoughts or both.
Yes, this site and its content, started some 4 years ago, should be seen as a work in progress. All findings are preliminary, all conclusions are tentative.
To business: here are the results from today’s experimentation, dare one say model building:
Late addition (29th Jan): the technique of smearing oil onto the template was first introduced on this site way back in October 2014 when exploring direct scorching from heated metal templates. As soon as the idea arrived that a cold template could be used to create a flour imprint on linen, heating the imprinted linen instead of the metal, then an agent was needed to help the flour adhere to the metal. That’s when oil put in its first appearance here, and has since been routinely used with an increasing number of template materials – terra cotta, plastics and now human skin -hands initially. (The oil only became necessary when the switch was made from imprinting with (a) wet flour slurry onto dry linen, to imprinting with (b) dry flour onto wet linen – that being a late stage of method development designed to achieve a fuzzier more TS-like image). But vegetable oil, even as virgin olive oil, is not the most user-friendly of substances to have to smear on one’s face, eyelids especially, as has currently needed to be done. Or does it? An agent introduced initially for use with metal is not necessarily needed for skin (while noting that oil was found to speed image development in the oven).
So a quickie comparison has been done of three pretreatments of skin (my fingers) before coating with dry flour and imprinting onto wet linen:
- None (flour dusted onto skin directly with no binding agent)
- Smeared with oil, then dusted with dry flour.
- Smeared with a thin slurry of white flour in water, then dusted with dry flour.
Here’s a gallery of pix showing appearance at different stages. The captions describe the facts. Discussion of results and final choice of imprinting medium is in the Comments attached to this post.
Extract of comment, received yesterday (29 Jan) from Thibault Heimburger:
Looking again and again at the TS image of the face (positive and negative), the mystery remains. How is it possible for a medieval forger to produce BY CHANCE an imprint that after tone reversal gives a perfect (absolutely perfect) human face ?
It is NOT a question of aesthetic.
It is a question of subtlety of the imprint.
See my reply beneath it, to which I would add this image, one that needs no further comment or explanation:
Update: 31st Jan 2016.
Here’s a screen grab from two of yesterday’s comments. the first my own, and the holding answer from Thibault Heimburger:
I greatly look forward to hearing what Thibault Heimburger has to say regarding the density gradients in the TS image. It’s a topic that I explored a while ago, using the Thermal LUT mode of ImageJ to perform ‘easy’ visual analysis of TS facial density gradients, avoiding a welter of numbers:
Update: Monday 1st Feb 2016: Am still fining-tuning the procedure for taking a minimally-distorted imprint off a REAL human face.
Simple experiments with a hood have confirmed the importance of pulling the linen taut UNDER the chin, so as to stretch it over the nose and lips, together with a little diagonal tugging down over both cheeks so as to prevent creasing. But the technique does not prevent creasing altogether. Does that matter where matching the TS image is concerned? I’ve chosen the Enrie negative to remind folk of the two prominent creases at TOP and BOTTOM of the head. Why is there so little discussion as to where they came from??? My model provides a simple answer.
Reminder: flour imprinting allows one to decide in advance which parts of the face will be in the final image, and which excluded, notably a preference for frontal over lateral planes so as to avoid image distortion. The underside of the chin can also be wiped, allowing one to pull the linen taut as described above without imprinting that area. In other words, the ‘mask’ like look of the TS, with those severe lateral cut-offs, are easily accounted for in the flour-imprinting model. Note too the sides of the nose have been wiped. But as I had to remind a commentator here, models are for using, not believing. Much still remains to be done to get something that matches the subtlety of the TS image (while recognizing that some of that may be due to centuries of ageing).
2nd update: Feb 1
Have just received this comment from Thibault Heimburger regarding the use of ImageJ’s Thermal LUT mode to visualize image density gradients.
Since this posting is already becoming too long, I’ll simply insert a graphic and caption here that responds to the first point raised (the use of the Min.% control bottom right). Further discussion can be found under Comments.
New update: Tue 2nd Feb 2016
Re the second part of Thibault Heimburger’s question, I think I’m now in a position to explain the subtlety of the TS image (which I’ve always acknowledged) if as I now believe it is reasonably well modelled as a flour imprint – even if that is not the precise technology that was employed. The model merely serves as an example of how a seemingly mundane way of producing a contact imprint can give rise to “subtlety” which mirrors that of the TS image. But first it’s necessary to address the specifics, namely the intermediate levels of image density that are present in the TS image. In fact, one can see those in the standard images of the TS, viewed with the naked eye, whether as positive or negative images, whether as Enrie or Durante images. But the focus right now is on the tool offered by ImageJ to view image density mapped as colour coded artificial relief, as shown above with the simple example of a circle with increasing image density towards the centre being converted to a colourful conein the Thermal LUT mode (LUT= Look Up Table).
Yes, the same Thermal mode shows the expected gradation of image density in the TS, or as Thibault correctly observes, the highest relief (shown as red) having beneath it an intermediate relief colour (yellow). What was he expecting? The lowest relief immediately (blue) with no gradation? Why? Had that been the case the TS image would have looked like a rubber stamp imprint, a crude all-or-nothing imprint, showing a total absence of “subtlety”, read crudeness. But even my flour imprints (and before it the Mark 1 direct scorch imprints off a heated template) pass that test of “subtlety” in ImageJ’s Thermal LUT mode, as shall now be shown.
First, here are flour imprints off my own fingers shown earlier in this posting that will be used as indisputably an entirely man-made image:
Min. % = 13 (scale lower right)
Note then that the intermediate yellow zone beneath the red is NOT exclusive to the TS image. Put another way, if that yellow zone is a marker for “subtlety” then the flour-imprinting model could be said to pass the subtlety test with, er, flying colours (well, partially elevated ones anyway, if not totally airborne).
I shall shortly be adding two images that I hope will demonstrate the manner in which two entirely independent mechanisms of 3D image capture, mutually reinforcing, synergistic one might say, come into play that result in the semi-photographic like character of the final imprint. Time to get my camera out, and a bag of flour, and a sheet of linen…
If one set out to find a contact imprinting method that was most likely to capture 3D-ness, computer software-aided that is, it’s hard to imagine one that is better than the flour-onto-wet-linen method.
3D–ness is captured in the very first stage of sprinkling flour from above the recumbent subject, since the flour settles under gravity (read orthogonally in those radiation models) mainly but not exclusively on the flattest relief.
In a recumbent human subject (e.g. the Man on the TS) the flattest relief IS the highest relief!
Then there’s the moulding of wet linen to the body relief.
Again, it’s the highest flattest relief that gets the most contact, the linen tending to make bridges between one prominence and another where there are intervening crevices and hollows. So one has a second entirely independent mechanism that favours the highest relief over the lower relief, such that a 2D imprint will have gradations of light and dark that give visual clues to the 3D relief of the parent template.
That’s the imprinting in general terms. One also has detailed aspects to consider where particular features of anatomy are concerned, like the nose, mouth, chin, the crossed hands, the feet. Let’s postpone further discussion on those for a day or two. Suffice it to say that flour imprinting can and does deliver the goods!
Two more images, by request from Thibault Heimburger (see Comments, this posting, 4th Feb, re his need for highest definition pictures).
Afterthought, added Friday 5th Feb
Have just remembered that one can use one’s printer scanner to obtain higher resolution pictures if desired (in this case it is Thibault Heimburger who has made the request which I’m only too happy to oblige). Fortunately I had not thrown away the linen with those flour imprints from my fingers. Here’s some images from the first scan, with the resolution set at its maximum (300dpi), approx 4 times greater than those above from the camera (and without camera shake!).