Another Lightning Composite

August 18, 2008
Tags: abstract, lightning, weather

I watched an amazing lightning show from Howell Mill Road a few weeks ago.

Technical explanation: for each lightning strike I used Photoshop's "difference" blending mode, which subtracts the "lightning" exposure from another exposure that contains no lightning. The result is an image containing only the changes between the two exposures, which in this case consists of the additional light created by the lightning itself and nothing else. I then combined the difference images from several lightning strikes using the "lighten" blending mode, which is similar to exposing multiple shots on the same piece of film.

In this case the street lights turn black because they are bright enough to expose as pure white in the original image, and the lightning cannot "brighten" something that is already pure white. White minus white is black. This is a limitation of digital sensors.

Feel free to check out some of the unmodified source images if you're curious.