After a full year as a public beta, Adobe began shipping [Photoshop Lightroom][1] earlier this week. Image software traditionally falls into two categories, photo cataloging software like Apple's [iPhoto][2] or Google's [Picasa][5] for organization, and image editing software like Photoshop or Paint Shop Pro for working with individual files. Adobe Lightroom straddles these two categories and is part of a significant new kind of photo software -- RAW workflow software. 

With more digital camera manufacturers including RAW image capabilities in increasingly less expensive cameras, a whole new crop of digital tools has sprung up to accommodate the more complex workflow RAW images necessitate. Others in this hybrid realm include Apple's [Aperture][3] and Bibble Labs' [Bibble][3].

Lightroom is designed to make it easy to quickly browse your photos, highlight the ones you like (via ranking, tagging and some other means), applying enhancements and corrections to the photo, and exporting the photo for web or print.

Lightroom's workflow is divided into five modules, Library, Develop, Slideshow, Print and Web. The Library module serves to organize and browse your images. Importing photos can be done direct from a camera or existing files on disk. The import dialog has a "File Handling" option, which allows to to control whether Lightroom works with a copied file or leaves the image where it is and simply references it. 

The Library module lets you edit meta data, add keywords, search for images and organize your photos into collections. There's also a "Quick Develop" panel for simple image manipulations. 

For more sophisticated editing options you'll want to jump over to the Develop module, which is where the majority of Lightroom's features congregate. 

The Develop module offers the traditional slider-based methods of adjusting exposure, tone and a myriad of other options, but Develop also allows you to grab and drag the image histogram directly. 

In the upper right panel of the Develop module is a preview thumbnail, rolling your mouse over the various image setting presets shows the results in the preview thumb before they're applied to the image. Frequently applied adjustments can be saved as custom presets.

All of the adjustment panels in the Develop module have a one-click on-off "switch" making it easy to review settings.

The Develop module also has a history panel and snapshot tool which makes it easy to jump forward and backward through development steps and mirrors the functionality of same tools in Photoshop.

Although the goal of Lightroom is to allow for quick editing, some images will naturally require more intricate adjustments than Lightroom is capable of. One area where Lightroom falls short is image sharpening. The controls in Lightroom are limited to a single slider to control the amount of sharpening, whereas Photoshop offers additional controls over radius and threshold settings. 

For those times when Lightroom is not up to the task, Lightroom offers tight integration with Photoshop, including the ability to do non-destructive roundtrip edits. Using the "Edit in Photoshop" command, Lightroom will pass off an image to Photoshop where more sophisticated edits are possible, such as applying a filter or performing fine grained touch ups. 

When sending an image to Photoshop, selecting the "Edit a Copy With Lightroom Adjustments," the default option for RAW images, will convert your raw image to a TIFF or PSD file for editing. After editing in Photoshop your changes will appear as a new image in Lightroom. By default Lightroom nicely "stacks" the various duplicate images, saving display space in the Library Module. Every stacked image in has an icon to show the number of images stacked and clicking on the edge of the image will expand in collapse the stacks. 

Once you have your images looking the way you want them the last three modules, Slideshow, Print and Web, allow you to export the final product to a variety of formats.

Regrettably the web module doesn't seem to offer any integration with popular online photo sharing sites, but the good news is that Lightroom offers a plugin architecture for third party developers to fill in the functionality gaps. Unfortunately Photoshop plugins do not work in Lightroom due to differences in the way the two applications handle photos.

Other nice features in Lightroom include the ability to "watch" folders which means if you add photos to a folder in another application, Lightroom automatically adds them to the Library. 

Lightroom was fast and responsive in my testing (Macbook Core 2 Duo 2.0 with 1gig RAM) in both OS X and Windows, though as with any image app, you can never have to much RAM.

Lightroom is aimed squarely at the RAW photographer and while Lightroom can handle other formats, it is probably overkill for the casual user. Nor is Lightroom intended to replace Photoshop, it lacks the refined editing tools of a dedicated image editing program.

Lightroom costs $300, but Adobe is offering an introductory price of $200 through April 30.

links:

[1]: http://www.adobe.com/products/photoshoplightroom/ "Adobe Photoshop Lightroom"
[2]: http://www.apple.com/ilife/iphoto/ "Apple iPhoto"
[3]: http://www.bibblelabs.com/products/bibble/bibble4.html "Bibble Pro"
[4]: http://www.apple.com/aperture/ "Apple Aperture"
[5]: http://picasa.google.com/ "Google Picassa"