#til

#TIL: Autochrome is a colour photography process patented in 1903 that uses multicoloured microscopic potato starch granules to make some of the first colour photographs.

Developing Autochrome glass plates is akin to making black and white positives (a process that’s still in relatively wide use today) — but with a twist. Unfortunately, constructing them is a laborious and expensive process. As noted on Peta Pixel, there’s just one person who’s actively working on it today: petapixel.com/2024/05/06/m…

Autochrome plates are created by methodically and evenly spreading a random mosaic of mixed microscopic starch beads, which are individually painted orange, cobalt, and green. When the light passes through that mosaic, it exposes black and white emulsion behind it while each bead acts as a tiny colour filter — effectively making a localized trichrome.

Once a matching light wavelength freely passes through the bead “lens filter,” ex. green light through a green bead, it registers on the emulsion. The emulsion, when developed as a positive, appears transparent — but the green bead makes it look green again.

Now repeat that for millions of other coloured beads, and you will get a full-colour photograph.

This video explains Autochromes quite well: youtube.com/watch?v=hE3KjK… and the Wiki page: en.wikipedia.org/wiki/Auto…

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