4. Develop module image editing

Photograph: Monument Valley, Utah, © Martin Evening 2009 Canon EOS 1Ds Mk III | 130 mm | 200 ISO | f8 @ 1/400th

A definitive guide to working with the image processing controls in the Develop module

One of the most powerful features in Lightroom is the image processing engine and the way the image adjustment processing is deferred until the time you choose to edit in Photoshop or export an image. This method of image processing actually originated in the early days of computer imaging, when deferred processing was adopted by programs such as Live Picture and xRes as a means to speed up the image editing. Computers were a lot slower back then, but it was possible to manipulate large image files in real time on relatively slow computers (with as little as 24 MB of RAM memory) and defer the image rendering process to the end of a photo edit session.

Of course, these days, you can edit large images in no time at all in Photoshop. But one of the key advantages of Lightroom is that you can apply a crop, spot the image, make localized adjustments, tweak the color, do some more retouching, readjust the crop again, and so on, without ever touching the pixels in the original photograph. In a conventional pixel-editing workflow, the pixels are always modified in a consecutive sequence of steps. When you work in Lightroom, no restrictions are placed on the order in which you do things and the edit changes you make in the Develop module are only applied when you output a photo as a rendered file, such as a PSD, TIFF, or JPEG.