This image of original size 4096x4096 contains all 256x256x256 colours in the RGB spectrum once and once only, and is a variation on the Simple RGB Coverage experiment, where all three colour components, instead of just one, form circular patterns.
<p>An optical illusion emerges in this case: darker dots seem to appear and disappear at some of the intersections in the green/yellow grid.
</p><p>It's also notable that this image only seems to show shades of red, yellow, green and dark blue. Shades of other colours are also present, but because of the way pixels are allocated, they get averaged out in the wider view.
</p><p>This image is constructed with 3 nested levels of tiles.
</p><p>At the inner level there are 256x256 mini-tiles composed of 16x16 pixels. Within each mini-tile, each of the 256 pixels has a unique intensity for the blue component. The intensity decreases with the distance of the pixel from the centre of the mini-tile.
</p><p>At the middle level there are 16x16 mid-tiles composed of 16x16 mini-tiles. Within each mid-tile, each of the 256 mini-tiles has a unique intensity for the green component. The intensity increases with the distance of the mini-tile from the centre of the mid-tile.
</p><p>At the outer level there is only 1 maxi-tile composed of 16x16 mid-tiles. Within the maxi-tile, each of the 256 mid-tiles has a unique intensity for the red component. The intensity decreases with the distance of the mid-tile from the centre of the maxi-tile.
</p><p>Out of the 48 possible colour allocations, this is the one where the grid illusion appears to be the strongest.
</p><p>For a variation on this image see Zoom 2x2 on Grid Illusion.
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P.S. on checking visually similar images already posted on allRGB, the Bling by ACJ and the RGB Spiral by JonSneyers look very close to this image, the only apparent differences being the allocation of colours and the choice of an expanding square instead of a circle pattern.
Fulvio Baccaglini
CC BY-SA 4.0
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