The eye believes what it thinks it sees

By Harold Davis | Published December 14, 2011

The eye believes what it thinks it sees. This allows us to enjoy magic shows, movies, and two-dimensional art such as painting and photography. Any two-dimensional representation of three dimensions is of course an illusion.

Problems begin when the brain gets into the act. The brain thinks it is the smart one, and doesn’t like playing the sap. If the first impression of reality isn’t utterly convincing then everything is subject to analysis—to the detriment of the viewing experience. In the writing trade, when this happens it is said that disbelief is no longer suspended.

In other words, we look at art to start with “willing suspension of disbelief.” As long as the artist doesn’t wantonly offend apparent reality this suspension of disbelief allows one to get away with murder.

Like trust, once belief is gone it is hard to earn it back. The best tactic is not to lose it in the first place.

The good news is that the brain isn’t as smart as it thinks it is. Whether belief is suspended or not, every time the brain will go for the simplest explanation—even when cursory observation will reveal that an image is the result of complexity and artifice.

Black Glass © Harold Davis

Case in point: Black Glass (shown above) seems to be a photo of glassware captured on a mirror that reflects a perfectly black background. However, this is by no means the case. The composition was shot using a mirror with a white background, as you can see here (the image is shown as shot towards the bottom of the HDR is Technique, Not Style article).

Given that the image was shot on a white background, how did I achieve this version? Answer: In post-production I swapped the luminosity information. A little more technically, in Photoshop I converted to the LAB color space, selected the L-channel, and applied an Invert adjustment.

The interesting thing is that this inverted the glass itself as well as the background. So, in the image above, the eye thinks it is seeing glassware. But if you compare this version to the original you’ll see that it is actually rendering the negative space created by the outlines of the glassware rather than the glass itself!

Here’s another example: take this shot of a wave I made on Point Reyes, California during a workshop I was leading:

At a casual glance, this photo looks simply like a breaking wave. If you look a little longer, though, the sense of scale becomes extremely peculiar because the line in the foreground appears to be a perfectly normal wave. If the foreground wave is normal size, then just how huge is the crashing, splashing wave that is the main subject of the photo?

The answer, of course, has to do with photographic perspective, and the illusion of perspective. I shot this photo with a long telephoto lens (450mm in 35mm terms) lying down in the sand on the beach. But that is not what the eye sees, and in this case it is what the eye doesn’t see that makes the image both perplexing and interesting.

Related story: Impossible Images.