DPP Home Software Image Processing Photoshop Lightroom, Part 2

Tuesday, June 26, 2007

Photoshop Lightroom, Part 2

Although Photoshop gets all the glory, in Photoshop Lightroom, Adobe has created a tool that will help professionals take control over their image libraries and catalogs of work

Lightroom Under Colors, there are two related but subtly different saturation controls. Vibrance makes a nonlinear increase (or decrease) in saturation. This means that unsaturated colors get more of a boost than already saturated colors, but with a twist—it “preserves” skin color. Saturation is an overall saturation boost.

Last year, I embarked on a photographic expedition to Antarctica. You may note that Seth Resnick, John Paul Caponigro, Stephen Johnson, Michael Reichmann and I all traveled to Antarctica for the purpose of leading 46 intrepid photographers on a photographic orgy, and some of the results are being used to illustrate this story. Well, aside from learning more than I ever wanted to know about “Metadata Templates” from Seth Resnick (Mr. Metadata), I also observed an unusual tendency by Seth. It seems he just loved to push the saturation in Camera Raw to about +17 in almost all of his shots. Well, with the advent of Vibrance, he has now upped his numbers (and rarely uses Saturation anymore).

The Rest Of The Controls

The balance of the controls in the right panel of the Develop module are basically the same as those found in Camera Raw.

Detail is for setting “capture” sharpening for an image. It's intended only to restore the apparent loss of sharpness encountered in digitizing continuous-tone scenes. The Luminance and Color Noise (here grayed out because of a black-and-white image being loaded) are rather light-duty tools. Work is being done to improve these parameters, but several third-party applications and plug-ins can do a better job.

The Lens Corrections are for fixing one flavor of chromatic aberrations, while Lens Vignetting corrects for dark corners.

Lightroom Probably the most confusing, yet critical function is Camera Calibration. No, neither Lightroom nor Camera Raw (the basis of the Lightroom RAW-processing pipeline) can use custom camera profiles. I doubt they ever will because of the way in which Thomas Knoll, the author of Camera Raw, designed the demosaicing and color rendering. Thomas does two non-ICC profiles and uses these profiles (one at Standard Illuminate A or 2856K and D65) to render a camera's spectral response to light. He employs the calibrate function to allow users to adjust the color rendering based upon their own camera's variations. And, yes, this can be a bit confusing, but it does allow users to fine-tune the color rendering for their cameras for more accurate rendering results. Bruce Fraser has written about this at CreativePro.com. Search for articles by Bruce Fraser and look for “Out of Gamut: Calibrating Camera Raw.”

LightroomOne slight hiccup is the way Lightroom displays color readouts. Rather than the traditional (and expected) 0 to 255 in RGB, the readouts are actually 0% to 100% in RGB, so traditional color-space readouts don't translate. Why? Well, that's a long and torturous tale, but one particular engineer, Mark Hamburg, decided this would be so, and so it is. Admittedly, since Lightroom uses an unusual color space internally (ProPhoto RGB Chromaticities and a linear gamma for processing, but an sRGB gamma tone curve for histogram display), there are no traditional color readouts to be had. Insiders call the Lightroom color space Melissa RGB, named for one of the Lightroom team members. (We like it because as far as we know, it's the first color space named for a woman.)

One of the functions found in Develop is the ability to view a before/after of an image's settings. This was a gee-whiz feature when it showed up in Lightroom Beta 2.


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