If we take the question of the image formation without also taking into account the rest of the important data coming from the Shroud, I would say that even if Colin Berry could really produced an image on linen that would show ALL the chemical and physical properties of the Shroud image (I’m 99% certain that he can’t because, among other thing, there is absolutely no color penetration anywhere on the Shroud, which is something no medieval forger using the kind of chemical process he proposed could have rationally achieve), his result would never prove that this is how the Shroud image was formed. This would only show that the kind of "artificial" process he proposed can produce an image on linen like the Shroud, which is very different than claiming this MUST be the way it was done.
And more importantly, the evidence coming from the bloodstains (which I have summarized in this paper: http://shroudnm.com/docs/2012-07-26-Yannick-Clément-The-evidence-of-the-bloodstains.pdf) would still be there to contradict the idea of a false relic that could have been "artificially" created by a forger. As I showed in my paper, the blood evidence coming from the Shroud is enough to prove that this cloth is a real burial cloth that has enveloped only for a short period of time a real scourged and crucified man that has been executed with the known historical method that was used by the Roman Empire before the reign of the Emperor Constantine. In such a context, the ONLY rational hypothesis that could involve a forgery is the one I summarized in the point #1 you can find in page 6, which goes like this: "It is a real burial shroud of someone other than Jesus of Nazareth who suffered the same tortures as he with a forged image done by someone without using any art technique. In this case, a forger “naturally” produced the image while using a real human corpse. Because of the great resemblance between what happen to Jesus in the Gospels, we must assume that this forger did it in order to produce a false relic of the Passion of the Christ. Also, because of the presence of many differences between any known artistic depictions of the Passion of the Christ prior to the first known public exhibition of the Shroud in the 14th century and the bloodstains and the body image that are on the Shroud (for example, the nailing in the wrist instead of in the palms, the wearing of a cap of thorns instead of a crown and the very distinct dumbbell shaped marks of scourging coming from a Roman flagrum), we must assume that if he tortured and crucified himself (with the help of some collaborators), this forger was well aware of the Roman procedures concerning scourging and crucifixion. In fact, it is even more rational to think that this forger used the body of a real crucified victim who was put to death by the Romans, before the crucifixion was banished by the emperor Constantine, in the last years of his reign that ended in 337. We also have to assume that this forger took the dead body out of the shroud before it started to corrupt in such a way that this extraction did not disturb the bloodstains, never broke the linen fibrils under them and did not disturb the body image. In sum, this scenario can be described like a “natural” forgery using a real tortured and crucified body. And whether or not the forger knew that he would obtain a body image on the cloth, along with the bloodstains, is not completely clear. In fact, the formation of an image like that could have well been just an accident."
If Berry (or anyone else) still wants to defend the idea of a forgery while remaining rational, I urge him to think seriously of what I just said and to try to find a way to produce a Shroud-like image with the use of biological products that could have been released inside the Shroud shortly after death by a highly-traumatized human corpse that had been scourged and crucified. In my mind, that would certainly be much more interesting than seeing him constantly trying to produce at all cost a Shroud-like image with the use of a man-made technique, while completely leaving aside (or at the very least, not considering seriously) the crucial evidence coming from the bloodstains…