More on coloured shadows

In a previous post I showed the photograph below and wrote about some other demonstrations of coloured shadows.

In a subsequent post I discussed how coloured shadows appear to obey the rules of subtractive colour mixing, rather than the rules of additive colour mixing that you’d expect to apply, given that the coloured shadows appear to be coloured lights projected onto a screen.

Earlier this year I did a screenprinting course at Edinburgh Printmakers. For my course project I decided to do an analogue of the photo above, doing literal subtractive colour mixing using pigments. Here is the result:

Comparing this image with the one at the top, we can see subtractive colour mixing rules at work in both. For example, where blue/cyan and yellow overlap, we get green. (If I’d been paying more attention I would have made the order of the coloured shadows the same in both images.)

To create the screenprint image, I took 5 photographs of the pot and its shadows.

Three of the photographs were to get images of the shadows. I placed the light in a different position for each one. In the fourth picture I arranged the lighting to get a good silhouette of the leaves, and in the fifth picture I arranged the lighting to get good highlights on the pot, to bring out its shape.

I then removed the irrelevant parts of the images and thresholded what remained to give me my originals for the four layers of my screenprint. The image of the pot/leaves is a composite of the fourth and fifth pictures above.

I printed the three coloured shadows first, and then the pot/leaves in dark grey on top.

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