This instructable documents how to machine a full color photograph by layering and machining different colors of transparent resin. In previous Instructables (here and here), I’ve shown how a black and white image can be made by layering a transparent black layer, of varying thickness, over an opaque white layer. The thickness of the relief determines how much of the white leaks through, creating different shades. This process is similar. First, a white layer of resin is poured and then machined. Then cyan is poured over the white and machined. Then magenta, then yellow. By controlling each layer’s thickness, we can mix a full range of colors, and reproduce an image.
CMY is a subtractive color model. Its three primary colors – cyan, magenta and yellow – can be mixed to make all possible colors (although in practice, the resulting black is imperfect). Most digital files, however, are saved in RGB color space. But this converts easily to CMY:
CMY = 1 – RGB
For example, say your pixel is orange, with an RGB = [1 .5 0]. Your CMY values would be [0 .5 1], or 100% of yellow and 50% of magenta. If we were to create this color value by layering transparent resins, we would begin with a white base layer, then a magenta layer whose thickness would give us half magenta saturation, and finally a layer of yellow thick enough to achieve full saturation.