Circular Distortion in Cylinder Rings

[mike_connell1]

<p>Not sure if this is a processing question, but here goes. Can anyone tell me what causes the distortion of the rings around the cylinders in this picture? It's kind of like a drop hitting water. It is especially prevalent on the second structure from the left. This is an HDR processed photo and the distortion seems static. In the single exposures, they fluctuate with size of the photo. It was really confusing because I didn't see them in Lightroom, but they appeared in Photoshop and I discovered that they could disappear at some sizes. This was taken with a Canon 30D with a Canon 10-22mm lens, f11 @ 10mm. The phenomenon is present at larger apertures and longer focal lengths.<br>

<a title="Hutto Coop 3 by mdconnell67, on Flickr" href="http://www.flickr.com/photos/mdconnell/4206816809/"><img src="http://farm5.static.flickr.com/4060/4206816809_586da3de76.jpg" alt="Hutto Coop 3" width="500" height="307" /></a></p>

[Matt Laur]

<p>Do a search on "moire pattern." The rows of pixels, at certain resolutions, are interacting with the metal corrugation in the silo panels. This can be mitigated by using different moire removal routines, or handling the down-sampling of the file in specific ways. <br /><br />It is distracting in that image, to be sure. But honestly? The first thing that caught my eye is the haloing around the silos, where you made tone changes. That always looks kind of unnatural, and takes away from the image, I think.</p>

[peano]

<p>You can read up on the cause of moire <a href="http://en.wikipedia.org/wiki/Moire">here</a> . The horizontal corrugated ribs of the silos are intersecting with the horizontal lines of the monitor -- at slightly different angles. All those intersections are causing the dark, concentric bands.<br>

.<br>

Russell Brown has a tutorial for removing moire, but it works only if one channel doesn't have the moire. In your image, all three channels have it. So, unless you are lucky enough to have a "magic" image size that doesn't exhibit it, you're probably stuck with it.</p>