Halftone effect

I mentioned one curious effect of the shroud image is that you cannot discern the image when you are close to it. The reason for this is the image uses the halftone effect.

Halftone is the reprographic technique that simulates continuous-tone imagery through the use of dots, varying either in size or in spacing, thus generating a gradient-like effect.

Where continuous-tone imagery contains an infinite range of colors or greys, the halftone process reduces visual reproductions to an image that is printed with only one color of ink, in dots of differing size (pulse-width modulation) or spacing (frequency modulation) or both. This reproduction relies on a basic optical illusion: when the halftone dots are small, the human eye interprets the patterned areas as if they were smooth tones. At a microscopic level, developed black-and-white photographic film also consists of only two colors, and not an infinite range of continuous tones.


Simply put, the halftone is an optical illusion: small dots of various sizes that are equidistant from each other create the appearance—at an appropriate viewing distance—of continuous gradations of tone. Due to the fact that many printing processes, can only transfer a solid film of ink to a sheet of paper (or other substrate), the halftone is the most effective method for reliably simulating a continuous tone image such as a photograph. Measured in lines per inch, the halftone screen is the essential building block of the printed page upon which everything else depends.


Halftone technique originated in the mid 1800’s.

No single individual can be named as the inventor of the halftone photomechanical process. William Henry Fox Talbot (British, 1800–1877) invented and patented his use of textile screens in 1852. Talbot, Georg Meisenbach (German, 1841–1912), Frederic Ives (American, 1856–1937), and Max Levy (American, 1857–1926) can be considered major contributors to the development of the halftone printing process.

https://www.getty.edu/conservation/publ … lftone.pdf

Here’s an example of a halftone picture.


Close up, the photo is just a bunch of black dots of various sizes, but when you look at it far away, it reveals an image.

Here’s a closeup of a photo I took from the shroud. When closeup, it’s hard to tell what it is.


So, if it’s a medieval forgergy, why would the artist use the halftone effect?
How did he even know about it?
How did the idea even enter his head?
Why would he decide to use halftone?
Should he be credited as the inventor of it?