Smarter Image Processing
The Lightroom image-processing engine is notable for a number of reasons. Admittedly, there’s no support for CMYK color in Lightroom, so for prepress work you always need to use Photoshop to handle the CMYK conversions. But the good news is that there are no color management settings to configure, or color space issues or profile warnings to worry about.
Adobe has made Lightroom simpler to use than Photoshop—and, in my opinion, has done so without compromising the quality of color processing in any way. Lightroom uses a single RGB workspace to carry out all its image calculations. The space used is similar to the ProPhoto RGB space that was originally specified by Kodak. It uses the same coordinates as ProPhoto RGB, but has a gamma of 1.0 instead of 1.8. By using a 1.0 gamma, the Lightroom RGB workspace is able to match the native 1.0 gamma of raw camera files, and its wide gamut can therefore contain all the colors that any of today’s digital cameras are capable of capturing.
For these reasons, the Lightroom RGB workspace is ideally tailored to the task of handling the color-processed data from the raw camera files. Perhaps concerns about banding in wide-gamut color spaces have been a little overrated, because it’s really quite difficult to pull apart an image in ProPhoto RGB to the point where you see gaps appearing between the levels. The Lightroom RGB space uses a native bit depth of 16 bits per channel, which means that Lightroom is able to process up to 32,000 levels of tonal information per color channel. A typical digital camera is capable of capturing up to 4,000 levels per color channel, so it’s probably true to say that the Lightroom RGB workspace can safely handle all of the tone and color information from any modern digital camera.
Lightroom doesn’t use layers, but does recognize and import layered images (provided that the Backward Compatibility option was switched on when saving the file in Photoshop). If you need to do any kind of layering work, it’s quite easy to choose the Edit in External Editor command, carry on processing the image in another program, and save the results back to Lightroom in the form of an edited copy version of the original master image.
A digital image is made up of nothing more than a series of numbers, and during the image editing process those numbers are changed to new numbers. The Lightroom image-processing engine ultimately reduces all of its pixel calculations into a single calculation by the most direct route possible to produce a mathematically purer, processed result, in which any image degradation is minimized.
Another advantage of the Lightroom image-processing engine is that you have the same full access to all of the image controls when working with JPEG, TIFF, and PSD images as you have when working with raw camera files. You can use all of the image controls available in the Lightroom Develop module—such as the White Balance, Exposure, and Tone Curve controls—to process any imported image. The Develop controls in Lightroom also now match the controls shared by the Adobe Camera Raw engine in the new Photoshop CS3 program. The Develop settings applied to images using either of these two programs are fully recognized by and compatible with each other.