Variegated images on the Shroud of Turin?

Linen in the first century, in the Middle East, was hank bleached. This meant that some yarn was whiter than other yarn. This resulted in variegated patterns as different hanks were fed into the loom. See: How the cloth was made and how the images formed.

Some of the bands of different shades of white (now yellowed and browned with age) are narrow and some are quite wide.

The variegation, or banding as it is sometimes called, is visual background noise and it alters the way we see things on the Shroud.

The face is gaunt, people often say. The nose is so  narrow; and the eye sockets exceedingly deep; the hair falls too straight.  True; but look carefully and you will see that the gaunt appearance is the result of  dark vertical bands on each side of the face. There are faint, less perceptible bands on each side of the nose and a horizontal band across the eyes.

Special image enhancement software (Fourier transform filters) can be used to mathematically find these bands and minimize their effect. Notice how this filtering technique seems to change the shape of the face and nose and makes the eyes look more normal. The hair is less forward. It doesn't actually change the shape of the face; it merely minimizes the  background noise and allows details to emerge.

It is most unlikely that the linen cloth used for the Shroud was produced in medieval Europe. Such cloth was field bleached after weaving. Medieval European linen was not hank-bleached. The woven cloth was soaked in hot lye solution, washed, soaked in sour milk and washed again. Following this treatment it was spread out in fields in the sun. This process eliminated variegation.