This is a typical "sphere on checkerboard floor" scene, but have you noticed the color blur?
This effect is called 'color dispersion' and occurs in nature because the index of refraction is not a
constant term. It varies over the wavelength of the incident light, so that light-rays of different
color are bend into different directions.
You can emulate this effect with a standard raytracer by rendering separate R,G,B-layers of the image,
each with the corresponding IOR-value for that wavelength, and then composing the layers with an imaging
software to the final picture. With this three color samples you get up to three color stripes instead
of a soft color blur like in WinOSi (which took hundreds or thousands of color samples for the above
In nature this effect is rarely seen, because the wavelength dependence is usually very small and all
lens-manufactures of course try to minimize this effect. However, some weeks ago I noticed exactly this
characteristic color dispersion blur looking through the waves in my water-glass onto a newspaper
behind it on the table.