Adobe Photoshop Lightroom 4 offers an impressive list of features, the vast majority of which will be familiar to those who explored the previously-released public beta Adobe made available in January.

These include a completely new book-creation module, expanded support for video, soft proofing capability, and geo-tagging of still and video images via a Google Maps-powered module. Image editing tools have also been significantly updated, with a new process version (PV2012) that includes a reworking of the Basic panel controls and new localized editing options. If you've spent time playing with the public beta and are already comfortable using these features, you can jump ahead to a listing of the few (and mostly minor) changes that have gone into the shipping version of Lightroom 4.

One welcome surprise to everyone, though, is Adobe's announcement of a 50% price drop. For the first time in Lightroom's five year history, the retail price is now $149 US for a full version. Upgrade pricing for current users as well as the student/teacher versions also see a (more modest) price reduction to $79 US.

I've been using the shipping version of Lightroom 4 for a few weeks with my own personal image catalog and in this review I'll take you through the tools and features that have changed since Lightroom 3. Keep in mind this is not a step-by-step Lightroom tutorial, rather an illustrated guide to what has been added and updated. My goal is to explain the new features so that you can decide whether the upgrade to Lightroom 4 is one you should make. Of course, if you've already decided to take the plunge, this article will help you get started in exploring these new features for yourself.

We'll take a look at the following features:

System requirements

Before we get started it's important to note that the minimum system requirements for Lightroom have changed. Lightroom 4 does not support 32-bit Macs. You must be running a 64-bit Intel processor and OS 10.6.8 or higher (read this Apple support document to determine whether your Mac has a 64-bit processor). On the Windows side, support for Windows XP has been dropped. Lightroom now requires a version of Windows Vista or Windows 7.

Develop module

Lightroom 4 introduces Process Version (PV) 2012. What's a process version and why should you care? Well, it's the image processing engine behind Lightroom (and Photoshop's Adobe Camera Raw plug-in). The Lightroom engineers make periodic tweaks to its components to provide better image rendering and/or enable new editing functionality. While the rendering performance sees some minor changes, PV2012 stands out by introducing a redesigned and recalibrated set of the Develop module's Basic panel tools, along with more localized editing options. Simply put, PV2012 is of huge consequence for every serious Lightroom user. Its changes are significant and will have a direct effect on your editing workflow.

As with the introduction of previous process versions, Lightroom, by default honors the current (in this case PV2010) process version of your existing images. If you desire, you can simply go on working as you always have. But should you choose to update an image to PV2012, a whole host of new functionality awaits.

Basic panel

Select any image in the Develop module that was imported in Lightroom 3 or earlier and you'll notice a warning icon in the lower right (shown below), indicating the image has not been updated to PV2012.

A warning icon appears at the bottom of the Develop module when an image processed via PV2010 or earlier (circled in red) is displayed.

After clicking the icon you can choose to update the selected image or all images in the filmstrip. Once an image is updated to PV2012 you will notice a revised collection of tools in the Basic Panel (shown below), as well as a noticeable change to the appearance of your image.

Gone from the Basic panel are the Recovery, Fill Light and Brightness sliders. Instead, what you see in Lightroom 4 is a separate grouping of sliders labeled Highlights, Shadows, Whites and Blacks. Moving any of these sliders to the right (a positive value) brightens pixels. Negative adjustments darken pixels. The default value for all items in the Basic Panel is now set to 0 for raw files, just as they have always been for JPEG images.

Many of the Basic panel controls
in Lightroom 3 (shown above)...
...have been changed in version
4 with default values set to 0.

It's very important to understand that for many of the Basic panel tools, the internal effects ranges have been changed, meaning that a slider value of say +50 in a PV 2010 tool may not correspond to +50 in the equivalent PV2012 tool. When updating PV2010 (or earlier) images which already contain manual Basic panel adjustments, slider values will be carried over or 'transposed' to the appropriate PV2012 settings. But the appearence of your image will change, often significantly. For this reason, I encourage you to apply PV2012 on an image by image basis to your existing photos to get a feel for what the new tools can do. Or simply import new images, which will automatically get the newest process version, and explore the new features with those images.

White balance

The WB selector's sample area is now zoom-dependant, mimicing the behavior seen in Adobe Camera Raw. Clicking with the WB tool on an image displayed in say a 1:2 (50%) view will result in a white balance calculation based on a wider range of pixels than performing the same action with the image at a 1:1 view. Put more simply, when you adjust the Scale slider for the WB selector's loupe window, the image area you see in the grid is now the same area that LR will sample to determine WB.

The loupe window of the WB selector
indicates the sampling area on which the
WB calculation will be made.
Setting the Scale slider to the lowest
possible magnification results in a wider
area of pixels from which to sample.

Sampling over a wider area of pixels should lead to more accurate WB settings in noisy images by minimizing the impact of random pixel values. In previous versions of Lightroom, a consistent grid of pixels was being sampled regardless of the image view or Scale slider setting.

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