Figureii
Generation
the same image, copied from itself, twice over
One source image, drawn once. Two chains, run side by side, the same number of times. Each pass in each chain takes only the output of the pass before it — there is no original to return to after the first step, in either column, which is what a copy of a copy means.
On the left, a photocopier: a fraction of a pixel of blur from the optics, a small contrast push, a little toner, and a sheet that never lands square. On the right, a lossy re-encode at a quality no one would ship, with the encoder’s block grid deliberately knocked out of register each pass so it cannot simply reproduce its own previous decision.
What this shows
A synthetic photograph — a face-like form under raking light, with a gradient sky, fine hair-like detail, a block of text-like marks and an eight-step grey wedge — is put through two chains and shown side by side at a generation the reader chooses, up to sixty. The left chain is a photocopier and it fails fast: by generation three the grey wedge has lost its middle steps, by generation eight the text-like marks have merged into a smear and the fine detail is gone, by generation twenty the face is a silhouette, and past thirty the image is a few crushed masses with toner speckle. The right chain is a lossy digital re-encode at quality 0.16 and it barely moves. Measured over the same sixty generations, the mean pixel shifts by roughly seven parts in two hundred and fifty-five; the face, the ruled line and most of the wedge are still legible at the end. The contrast between the two columns is the finding, and it is not that digital copying is better. It is that the thing which used to let anyone find the original by inspection — visible loss, accumulating with each remove — has been engineered out, and nothing has been put in its place.
Read the grey wedge at the bottom of each. It is eight even steps in the source. Watching them merge is how a printer reads damage, and the left column loses them within three or four passes.
The left is what everyone means by a copy of a copy. The right is what a copy of a copy now is.
The whole moral architecture of authenticity — the original, the forgery, the expert with a loupe — was an artefact of the copy being lossy. That is the left column. We fixed it. Nobody has proposed a replacement for what came down with the scaffolding.