John P. Jackson, Is the image on the Shroud due to a process heretofore unknown to modern science?, Shroud Spectrum International, no. 34, March 1990. (See Shroud Spectrum, No 34, Part 3)
That paper written by a well known Shroud researcher (technical director of the STURP group, which in 1978 made an extensive study of the Shroud) presents the theory that the Shroud image formed when the body dematerialized. This theory is based on three inferences, and in particular by the work of Gilbert Lavoie, which concluded that the bloodstains perceived in the hair were actually on the face. Because two of the three inferences appear contradictory, if we assume that the Shroud was not forcefully constrained (e.g. flattened) during image formation, Jackson proposes that the cloth was indeed not straight but that the body dematerialized and the cloth flattened itself by collapsing through the body. But are the three inferences correct? That is, is this theory trying to solve a real contradiction?
In Section II.A of Jackson's paper, three inferences, based on numerous considerations too long to summarize here, are made:
Notice that inference 3 appears in contradiction with inference 1 if we assume that no external force (e.g. a person flattening the Shroud) occurred. Based on this apparent contradiction, Jackson proposed the theory that the Shroud flattened by itself, by its own weight, when the body dematerialized. That is, the Shroud collapsed -- going through the body -- when the body dematerialized: this is the "Cloth Collapse theory". This reasoning is presented in Section II.B of his paper.
I think that the major problem with this reasoning is inference 3: the Shroud should be in two different draping configurations to form the bloodstains and the image. This aspect has been studied in a paper I published at the 2005 Dallas Conference -- it is available here. That paper concludes that, most likely, the Shroud was not flattened between the formation of the blood stains and the image. There are many reasons to support this conclusion, in particular the lack of any observable vertical misregister of the bloodstains and the image.
I conclude that the Cloth Collapse theory tries to solve an apparent contradiction which does not even exist.
Jackson -- who wrote his paper in 1990 -- predicted from the Cloth Collapse theory that an image should have formed on the reverse side of the Shroud. Jackson now claims that this has been confirmed by a paper of Fanti and Maggiolo published in 2004 (see reviews). But that paper has shown that no image could be detected on almost the entire reverse side of the Shroud. Perhaps only around the face could an image exist. But even the existence of that partial image has been challenged -- see a review of the Fanti and Maggiolo's paper in this section.