Jules Scalbert (1851-1928) - Le Bain (date not found) colour recombination

If this image looks a little soft and waxy, it's because the original public domain version was very small, so I've taken the liberty of upscaling it using waifu2x. Now I know that upscaling is a dirty word in certain circles, but waifu2x is capable of performing the task more cleanly than conventional image editing software, thanks to its deep convolutional neural networks (whatever those are). It can't add detail that isn't there, so the results can appear a bit soft, but at least they're not riddled with pixellation and other unwanted artefacts. Anyway, if anyone doesn't like the upscaled image, feel free to shrink it using your own image editors.

 

This recoloured version was produced in the usual manner, by finding a coloured original that was even smaller than the black and white and then matching the geometry and superimposing only the colour data. In this case it works very well, with virtually no colour fringing at the edges of objects.

Done