Edge Detail in Lightroom 3 beta: what does it do?

Adobe Lightroom 3 beta offers many refinements and some new features over Lightroom 2. One of the most intriguing is a control labelled Edge Detail. The slider is intended to deal with the smearing of colour that you sometimes see in very high-ISO shots, when noise reduction has reduced the sharpness of edges and the colour might leak from one part of the image into another.

The edge detail slider at work

Here’s a very mundane picture. It wasn’t taken at very high ISO (just 500) but was pushed to about ISO 2,000 equivalent during post-processing and was taken on an older camera that has a very noisy sensor by today’s standards. (As a point of reference, any of you shooting the new Nikon D3S would probably need to go to ISO 25,000 or 50,000 to get anything quite this noisy.)

Now take a look at a detail from the image, first with the new Edge Detail slider set to zero and then, in the second crop, with the slider set to 100. Look at the way the edges of the orange indicator lamp are defined against the car’s bodywork.

You can see the effect of Edge Detail quite clearly—it appears to be adding sharpness and clarity to the colour edges, emphasising colour boundaries in a way that regular sharpening doesn’t and getting rid of much of the orange mush that you can see in the top picture. (In Lightroom, regular sharpening acts only on the luminance data—i.e., the brightness—and not on the colour. That’s intended to prevent colour shifts.)

Digital photography allows us to work in very low light but the level of colour noise reduction going on often smudges the colour; Edge Detail has been designed to counter that where it matters and can be quite effective—it just needs a better name.

Indoor, ambient-light photographer?

Although this slider is a feature of the beta version of Lightroom and could change (or even disappear) before the final release, it might be worth an early look if you’re an event photographer shooting with only ambient light and sometimes end up working in some challenging, low-light conditions. If the Edge Detail feature makes it through to final release, you’ll also see it in the corresponding version of Adobe Camera Raw (ACR) for Photoshop, which is rumoured to be ACR 6.

Workflow and notes

1. All the processing for the image above was carried out only in Lightroom 3 beta, and designed to show the effect of the Edge Detail slider as clearly as possible.
2. The only difference between the two crops is that the Edge Detail slider was moved from zero to 100—no other control was touched.
3. Lightroom 3 beta is a free download for Windows and the Mac, even for users who have no version of Lightroom currently installed. It’s beta software so it has bugs and some performance issues that will be ironed out before a final release. It will expire in April 2010.
4. All the images used above show lots of noise because Lightroom 3’s luminance noise reduction is disabled in the current public beta.

Training

In case you were wondering, our training is not this geeky—it’s about workflow rather than esoteric details! We put this stuff in the blog so we don’t have to spend as much time covering it in regular courses. If you find this kind of thing useful or interesting and know others who might, we’d love it if you could pass on details of our site.