Edge detection – Ripples

When light hits the retina at the back of your eye, important steps in the processing of the image are taking place before the signal is send to the rest of the brain. One of the very first steps is a contrast enhancing procedure. Effectively what happens is that a slightly blurred version of the image is subtracted from the original version as is shown below. This affects the image primarily at the borders of objects, in this case lining out the swan.

Using slightly different calculations I generated the image below to also pick out softer edges:

For the next step the user has to click with their computer mouse anywhere on an edge and a series of white dots starts to create a path along the darkest edges as shown in the image below on the left. At the same time this shape is repeated multiple times on the right, radiating outwards and increasing in transparency. This refers to a hallucinatory effect called after images or palinopsia, which is a common side effect of various types of hallucinogenic compounds like LSD, but can also occur when drinking alcohol.

Below two works are shown together with their original photos.