What the fourth photocopy does to a page

A Year 4 phonics workbook came in last week, filed as forty-one pages of grey. Someone had copied it from a copy in about 1995, then copied that. The left inch of every page runs black where the spine sat on the platen glass. Its vowel grid has faded to the colour of weak tea.

Each generation of copying takes something specific away. First the mid-tones go, then the hairlines, and last the difference between a comma and a speck of toner. By the fourth pass, a reader is guessing at punctuation.

The original was 300 dpi. The page in your hand is not.

The book was set from clean film, so its strokes began sharp. A photocopier does not copy that page. It copies its own reading of that page — whatever threshold the machine settled on that day. Every pass re-reads a slightly worse original and hands back a slightly worse answer.

Resolution is the wrong word for what is lost. A scan at 600 dpi of a fourth-generation page gives you a very precise record of mush. What went missing was tonal range, and no amount of sampling puts it back.

Grey goes first, then the thin strokes

Look at the background of a first copy and it is paper white with a faint warm cast. The second copy reads that cast as ink and prints it. By the third, the page carries a flat grey field that was never in the book, and the copier keeps adding to it.

Thin strokes lose the same argument in reverse. The crossbar of an e, the tail of a comma, the light stroke of a t: each sits near the machine’s black-or-white threshold. One pass rounds it down to nothing. After that there is nothing to recover — the mark is not faint, it is absent.

The staple shadow, the curl, the black gutter

Three kinds of damage arrive together on a spine copy. Staples leave a hard shadow where the sheet lifted off the glass. The gutter runs black for an inch because the bound edge could not lie flat. Text near that edge curves away, so a straight line of type arrives as a shallow arc.

These are geometry problems, and geometry is recoverable. A restoration pass finds the page edges, measures the curve, and flattens the type back onto a straight baseline. Grey that the copier invented can be measured and subtracted, because it is a field, not a mark.

Thirty copies means thirty copies of the damage

A worn master does not stay one problem. Run it through the machine for a class and every desk gets the same black gutter, the same grey field, the same missing crossbar. Thirty children then read the worst version of the page at once, at arm’s length, under classroom light.

Teachers already know this and work around it. They enlarge to 141 percent, darken two notches, and copy the darkened copy for next year. Darkening lifts the ink and the background together, so the page gets heavier without getting clearer.

What restoration puts back, and what it cannot

Restoration rebuilds contrast and geometry. It separates the text layer from the field the copier added, drops the field to white, and returns the strokes to full black. Skew and curl come out in the same pass, so margins sit square and the gutter shadow goes.

What it cannot do is invent ink that was never captured. If the crossbar of an e vanished in 1997, no pass can know whether the letter was an e or a c. Honest output leaves the ambiguity visible rather than guessing a stroke into place. That limit is worth stating plainly, because the alternative is a clean page with the wrong word on it.

One page takes 20 to 90 seconds to restore, and a batch holds up to 80 pages. A forty-one page workbook filed on a Tuesday evening is a clean master before the marking is done. Thirty children read that master, or they read thirty copies of the same smudge.