photohacker: DXO Optics Pro

When I first bought my DSLR and started gathering a little in-depth knowledge about photography, I quickly found myself overwhelmed by lots of buzzwords. "Chromatic aberration", "vignetting", "fringing", "lens flare", "distortion", "noise" -- just to name a few. These are all things I was never even aware of in the point & shoot camera world.

Luckily, there are some good pieces of software that can help you mitigate some of these problems without having to necessarily become an expert in each one. Why am I advocating that you not become an expert in each of these topics? Take a look at a snippet of an explanation of chromatic aberration by PA van Walree:

"When different colors of light propagate at different speeds in a medium, the refractive index is wavelength dependent. This phenomenon is known as dispersion. A well- known example is the glass prism that disperses an incident beam of white light into a rainbow of colors [1]. Photographic lenses comprise various dispersive, dielectric glasses. These glasses do not refract all constituent colors of incident light at equal angles, and great efforts may be required to design an overall well-corrected lens that brings all colors together in the same focus. Chromatic aberrations are those departures from perfect imaging that are due to dispersion. Whereas the Seidel aberrations are monochromatic, i.e. they occur also with light of a single color, chromatic aberrations are only noticed with polychromatic light."

Had enough? That's just the introductory paragraph of the document. It continues on in great technical detail. If you're fascinated by the nitty gritty and the paragraph I've quoted only intrigues you more, then I'd hate to be the one to dissuade you from learning more. But my point is that you don't have to be an expert in this stuff just to take a decent photograph. For most people, chromatic aberration can be distilled down to "some parts of your photos have purple colored edges."

Chromatic aberration is just one of the many optical irregularities that DXO Optics Pro addresses. It's the software I've chosen to use, and I'm extremely happy with the results it provides. I'll try to illustrate the benefits of the software by showing you some photos before and after being processed by DXO Optics Pro, and some of the optical issues that it resolved in the images.

Let's start with lens distortion. Here's what DXO has to say about it:

"A perfect lens would render straight lines as straight, no matter where they occur. Most practical lenses aren’t that good, though, and instead bend lines outwards (barrel distortion) or inwards (pincushion distortion). Wide-angle lenses and wide-range zoom lenses often suffer particularly badly from this."

I have some good examples of lens distortion in my photo collection, as I have primarily used a wide-angle zoom lens. Disclaimer: these pictures were chosen not because they are particularly good photos, but because they most succinctly illustrate the issues being discussed.

Initially the images you see are the unaltered images that came out of my camera. By moving your mouse over the image you'll be able to see the photo after it was corrected with DXO. Sometimes without having the photos side-by-side (or in this case, overlayed each other) it's difficult to notice the subtleties, but boy do they become apparent when you can flip your mouse over them and immediately see the before/after in full effect.

NOTE: If you mouse over the images and see no change in your feed reader, you may need to click-through to the full blog post.

Here we go with some barrel distortion examples:

Take a look at the balcony before you mouse over the image below. Once you mouse over it, you should see the balcony straighten up into a horizontal line.

Now take a look at pincushion distortion.

Pay close attention to the lines on the doors and the piping to the left of the doors.

Next, there's vignetting. Here's a quick note from DXO to keep in mind as you look at the images:

"Most lenses are brighter in the center than at the edges, especially when wide open. This is especially pronounced with wide-angles and some long telephoto lenses. This phenomenon is known as light fall-off or vignetting."