That "slit” is an artifact of the modern photography, a shadow of a fold that has collected dirt over the centuries, which disappears when the cloth is stretched in that area. SHEESH! You skeptics stretch anything to deny facts that are easily checked.
The perspective, detail, and resolution of the face is no greater or less than the rest of the image. The only ones who claim that are ignorant skeptics who have not actually done the experiments on actual bodies as REAL scientist working within their fields of expertise over the last 120 years have done.
The skeptics are led by the Joe Nickell, a failed stage magician, who has a degree in English Literature. Their primary scientist has a degree in GEOLOGY. . . Yet these two are challenging the findings of people with multiple doctorates and who publish their findings in peer-reviewed scientific journals.
Nickell claimed that three world class experts in hematology and blood fractions mistook the blood stains on the Shroud, after over forty specific scientific tests returning positive tests for human blood descendent materials, for what Nickell says is mere Tempera Paint made with chicken egg albumin and red ochre with some vermillion paint (mercuric sulfide). . . completely ignoring the fact that extremely accurate electron micro-spectroscopy had been done on the Shroud image and blood stains and found no mercury from mercuric sulfide or iron from red ochre, especially in the blood areas. . . But there was iron in the blood area which was identified as iron naturally occurring in hemoglobin and homoglobin descendant fractions.
That Electron micro-spectroscopic analysis is so accurate it can tell the analyst the specific manufacturer of the vinyl envelopes the samples were placed in before testing. Yet Nickell, in his pan-authority and amazing expertise, claims these scientists mistook Tempera Paint for human blood stains? Pardon me if I drip derision on Nickell.