August 04, 2008

The DNG Profile Editor: What’s it all about?

When we look back at how things changed with the arrival of Lightroom 2, I think the new DNG Profile Editor (presently kind of a sleeper technology) will stand out as transformative.  The technology was largely developed by Eric Chan, a bright young guy on the Camera Raw team (and aspiring photographer).  I’ve always found his explanations lucid and highly readable, so I’m delighted that he’s written a guest blog post on the subject.  Enjoy.  –J.


Hi everyone. My name is Eric Chan and I’ve been a Computer Scientist at Adobe since February, which doesn’t exactly explain how I ended up on John Nack’s blog. [People often wonder how they ended up here...  --J.] Well, John kindly invited me to share some thoughts on the new color profiles for Lightroom 2 and Camera Raw 4.5… "Whoa, hold on there!" you say, "New profiles? What new profiles? I didn’t see any new profiles!" Ahh, that’s because the new profiles are currently undergoing a public beta and aren’t shipping directly with LR 2 and CR 4.5. Instead, they’re available as a separate download from the Adobe Labs web site. Why a public beta? Simply because there have been many changes under the hood, and we want to give folks a chance to try the new profiles and provide feedback before we bake them for final release.


But I’m getting ahead of myself here. Let me backtrack and give you the big picture first. As it turns out, there’s quite a bit more going on here than just a new set of color profiles.

Many photographers have been asking us for better color from Camera Raw and Lightroom. Do you find deep reds becoming orange-ish and undersaturated? Is it challenging to nail colors under specific lighting conditions, like when doing a product shoot? Do you love our tools but prefer the colors from another raw converter (or from the in-camera JPEG preview)? Have you tried fiddling with the Calibration sliders (or cursed them because they don’t provide enough control)?


The good news is that we’ve produced a comprehensive and highly versatile solution that addresses all of these issues. First, there’s the updated DNG 1.2 specification, which expands and formalizes the concept of a camera profile for digital raw images. Next, we have two new sets of camera profiles based on this extended profile format. Then there’s the DNG Profile Editor, a free utility which can be used to roll your own profiles (or tweak existing ones). And finally, we’ve written up extensive documentation and tutorials to help you get the most out of these new tools.


Now let’s take a look at each one of these items in more detail, starting with some tech stuff. Back in April, we updated the DNG specification to version 1.2. The update includes a more complete and versatile camera profile format, optimized for raw image processing. In other words, these profiles apply to the linear, scene-referred data from a raw digital capture.


Profiles using the new format have several benefits. They produce better color, thanks to some new technical features. They can optionally be embedded in DNG files, making the color appearance of these images self-contained. And they will work in any raw converter that supports DNG 1.2. Yes, I know, for now this only applies to CR 4.5 and LR 2.0, but it’s still worth elaborating on this last point. The concept here, you see, is that DNG 1.2 camera profiles are designed for portability. If you’ve every fiddled with camera profiles in other raw converters, you may have noticed that they aren’t portable. For instance, trying to use one raw converter’s camera profile with another raw converter often leads to disastrous (though sometimes entertaining) results. We’re hoping that DNG 1.2 will change that in the long run.


Of course, a new profile format alone isn’t going to do much good in the real world, is it? Not unless you have some actual profiles to work with.


We have a new set of camera profiles called the Adobe Standard profiles. Our goal in designing these profiles is to give photographers a better default color: that is, a better starting point for making image adjustments. With the new profiles, the main improvement is in the warm colors: reds, oranges, and yellows. Deep saturated reds should indeed appear red, without messing up skin tones. Saturation is better maintained in warm highlights, and warm colors are easier to distinguish. There are also improvements in other colors, but the changes in warm colors are the most noticeable.


Some photographers have told us that while they like the workflow and the power of the tools provided by Camera Raw and Lightroom, they still prefer the color rendition provided by the camera manufacturer’s own software (which is usually equivalent to the in-camera JPEG). For these photographers, we have designed a second set of profiles called the Camera Matching profiles (currently only available for Canon and Nikon DSLRs). The only purpose of these profiles is to match the camera maker’s color. For example, applying the "Camera Neutral beta 1" profile to a Canon EOS 5D image in LR 2 should produce very similar results to what you would get from Canon’s Digital Photo Professional when using the Neutral Picture Style.


What about the DNG Profile Editor? What is this tool, and who is it for? Color, simply put, is highly subjective. Not only do we have individual color preferences (much like choosing a favorite film), but these preferences often depend on what we’re shooting. A single profile, even a highly accurate one, is unlikely to be suitable or even desirable for all of your images. We recognize that some photographers may want to create their own profiles or tweak existing ones.


To support this effort, we’re providing a free utility to the photographic community called the DNG Profile Editor. Please keep in mind that this tool is intended for advanced users. That said, it’s easy to use and we welcome everyone to try it. Basically, the way it works is that you specify an existing profile (called a "base profile") as a starting point, then use the editor interface to adjust a profile’s lookup tables, matrices, tone curve, or metadata. Once you’re happy with your profile, you can save it to disk and load it into CR 4.5, LR 2.0, or any DNG 1.2-compatible raw converter.


The DNG Profile Editor has many applications. You can build a profile that nails specific colors under a known, fixed lighting condition (such as when doing a product shoot). You can get matching colors across multiple cameras, within technical limits imposed by sensor differences; this is very handy for pros who often work with multiple camera bodies. (Yes, this means you can do funky things like make an Olympus camera look like a Nikon, and vice versa …) You can build special profiles for infrared-modified cameras, so that you won’t bump into CR and LR’s bottom limit of 2000 K on the white balance temperature scale. And for those of you familiar with CR calibration scripts, there is a Chart Wizard feature that automatically builds a profile with the help of a photographed 24-patch ColorChecker chart.


The Chart Wizard is particularly handy when shooting regularly under strange lighting conditions. For example, compact fluorescent light bulbs often have spiky spectra, leading to strong magenta or green casts in images even when a proper white balance is set. Yes, you can use the HSL adjustments in CR and LR to reduce these casts, but it takes a fair amount of experience to do so effectively without impacting other colors. The Chart Wizard takes the guesswork out of the process and is also much more precise, since it’s able to target and fix very specific colors (such as whacked-out greens, an unfortunate property of my kitchen lights…) while leaving others alone.


I’d better wrap this up before I end up with a book. In summary, for the past several months, we’ve been working hard on delivering better color when shooting raw. Our solution includes an extended camera profile format, new profiles, and a tool called the DNG Profile Editor. Since the profiles and DNG Profile Editor are still in public beta, we don’t provide official Adobe support for them. Even so, I think our unofficial support is pretty decent: there’s an online FAQ, tutorials, and documentation to help you get started with both the profiles and DNG Profile Editor. Please post feedback and questions in the User-To-User forums (see links below).



* Frequently Asked Questions (FAQ)

* DNG Profile Editor Tutorials and Documentation

* Camera Raw User-To-User Forums

* Lightroom User-To-User Forums

Posted by John Nack at 7:28 AM on August 04, 2008
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