Lossy WebP is built for photographs — it discards detail the eye does not miss in something full of
texture. A logo is the opposite: flat areas, hard edges, a handful of colours. Encoding one lossily is
worse than useless twice over. It softens the edges, and it makes the file BIGGER, because flat
regions are exactly what lossless compression is good at and exactly what lossy encoding turns into
gradients it then has to describe.
Measured, not theorised: fofos-logo-saffron.png is 300x300 and produced a 22,432-byte 256x256 rung
beside a 9,144-byte full-size one. A smaller picture, two and a half times the file.
The decision is measured too. Every heuristic for this is wrong somewhere — a PNG can hold a
photograph, a JPEG can hold a diagram, plenty of logos are opaque — so it encodes the smallest rung
both ways and keeps the answer. One extra encode of a 160-pixel image per original, and what comes out
is not an opinion about the file: it is the file saying which encoder suits it. Applied to every rung,
because an image does not stop being a drawing at 640 pixels. Recorded in the manifest, because
somebody wondering why one directory is shaped differently should find the answer rather than
re-derive it.
Two other things the logos exposed:
The ladder had no floor. It started at 320 and a logo renders at 80, so fofos-logo-black got a single
12,350-byte rung against a 12,678-byte original — a ladder that saved 328 bytes. 160 and 256 are now
the bottom, and 128 and 192 on the square side.
And square crops of things already square. Both logos are 300x300, so their square rung cropped
nothing: the same image under a second name. The aspect ladder already produces squares for a square
source. 2% tolerance, because a 1000x1002 photograph is square for every purpose this serves.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
pastilhasandClaude Opus 5
53b834a7a6