Two hundred supplier thumbnails, worked end to end

A supplier has sent a ZIP of two hundred product photographs. They open at somewhere between 480 and 900 pixels on the long edge, several are PNGs with a white background baked in, two are HEIC because somebody photographed the samples on a phone, and one is a spreadsheet that ended up in the same folder. The shop wants a thousand pixels minimum.

That is a throughput job, not a quality job, and the difference matters: the decision to make is not which network produces the nicest edge on one photograph, it is whether the whole set finishes inside an afternoon.

1. 1Drop the folder rather than the files. A directory drop keeps the relative paths, which is what keeps two suppliers' identically named files apart. The spreadsheet is counted as a non-picture on one line and never appears again.
2. 2Factor 2×. 480 becomes 960 and 900 becomes 1,800. The low end of that misses a 1,000-pixel floor by forty pixels, so either those few go at 3× in a second queue or the supplier is asked for better originals. Taking the whole set to 3× to rescue eleven files costs nothing in passes and nothing in time, because the pass count does not move with the factor — so on this site, 3× is usually the right answer to that question.
3. 3WebP, quality 82. The PNGs stop being PNGs, which is the single biggest saving available on a catalogue: a flat-background product shot as a PNG is routinely four times the size of the same picture as WebP, at no visible difference.
4. 4Naming {name}-{factor}x. SKU-4471.jpg becomes SKU-4471-2x.webp. The stem survives, which is what lets a spreadsheet of SKUs still match the folder afterwards.
5. 5Calibrate, then read the number. Eight real tiles from three of your own files. On a mid-range laptop the figure usually lands near the published 230 milliseconds; on a five-year-old one it can be three times that, and the estimate says so before you have committed to anything.

Pause is safe at any point and lands on the next pass rather than the next file. Closing the tab is survivable in the sense that the queue remembers where it was, and not survivable in the sense that it remembers your photographs — it does not, and the browser will ask for the folder again.

HEIC is what an iPhone saves by default. The codec is fetched the first time one turns up in a set and then reused, so two of them cost one download. A file that fails — a truncated download from the supplier, most often — is retried once at half the tile size, then marked failed with its reason and left behind while the queue carries on. The end screen offers a second queue built from the failed set alone, which on a catalogue is usually one or two files.

• Nothing here crops to a square, pads to an aspect ratio or whitens a background. Those are three different jobs on three different domains.
• An upscaled photograph of a badly lit sample is a larger photograph of a badly lit sample. This changes a size.
• The archive is written as the run proceeds, so cancelling halfway still leaves you with everything that finished.

• Catalogue intakeSupplier thumbnails against a marketplace floor: opens at 2×, WebP out, named for a shop.
• Listing minimumsWhat five marketplaces require in pixels, and the same queue set to clear it.
• Small sources, better resultsWhy a 500 px source beats a 4,000 px one on both quality and wall-clock time.
• Where the minutes come fromTile geometry read off both graphs, the per-pass figures, and the calibration that replaces them.