Cropping and Rotating Images in Adobe Lightroom
Even though everything in Lightroom is nondestructive, you aren't limited to just basic tonal corrections and contrast. While there are limits to what you can do, they lie far beyond just this. I've written already about sharpening in Lightroom, but you can also do such tasks as cropping an image or straightening a horizon. There are some great choices in how Adobe implemented this, but there are also some awkward ones.
First, Lightroom is a modular program with different modules designed to handle different kinds of tasks generally associated with different phases of working on an image. There's the Library module for importing and organizing images, the Develop module for doing the heavy lifting of optimizing the appearance of selected images, and the Slideshow, Print and Web modules for sharing the results of those optimizations via different media. Everything I'm going to describe here is part of the Develop module.
To crop an image, open it in the Develop module and click on the Crop Overlay tool in the toolbar. In the standard window configuration, you'll find it as the far left icon in the first row underneath the histogram. Lightroom lets users reconfigure panels quite a bit so you may have moved things around in your copy. It looks like a dashed white rectangle. When you click on it, the image you are working on will be outlined with a thin white border with somewhat thicker adjustment handles on each corner and in the middle of each side. The area to be cropped is what is defined by this border so by default your entire image is selected. You can select a smaller area either by grabbing the adjustment handles and dragging them inward as needed, or by clicking with your mouse anywhere on the image and dragging to open up a new selection border replacing the current one. Either way, you can fine tune your crop selection until you are satisfied by means of the adjustment handles. You can also click and drag on the overlay with your mouse to reposition things, but rather than moving the selection border over the image, this will move the image itself underneath the stationary selection border. To me this seems somewhat counterintuitive as it requires you to drag to the right in order to reposition the selection border closer to the left hand side of the image and so on. You must drag in the opposite direction than it seems (at least to me) like you should since you are not moving what (at least to me) you think you will be moving. Remember, even though you must click inside the selection border to do this, the image moves, not the crop border.
Everything outside your selection will appear slightly dimmed. So far as I am aware, you can't control the degree of dimming as is possible with the Crop tool in Photoshop. You might be tempted to think the Dim Level for the Lights Out mode on the Interface tab of the Lightroom Preferences would affect this but it doesn't. While I'd love to be able to darken the color somewhat, the opacity Lightroom does use is still quite workable. Note that the Navigator image will show the cropped version even before the crop has been completed so you can see the image without the distraction of what lies outside the selection this way too.
You may be pleased to find that Lightroom provides a grid overlay on your crop area. This can help you recompose your image, aligning things with the rule of thirds or other preferred divisions of the frame such as the Golden Ratio made famous by the ancient Greeks and medieval painters. To change to the overlay, choose Tools >> Crop Guide Overlay from the menus. There's also a selection for Tool Overlay on the bar underneath the image when the Crop Overlay tool is active. Hitting the letter "o" on your keyboard will cycle through the overlays. You can turn the overlay off completely via Tools >> Tool Overlay >> Never Show. Curiously, hitting the "o" key will still cycle through even if set to Never Show. If you do, you will find your menu will change to "Always Show."
The Crop Overlay tool also has tool options that normally appear in the toolbar directly below the bar with the icon for Crop Overlay when the tool is active. Here you can lock the selection to a standard aspect ratio and control other options. There's also a "Lock" icon that when clicked on will tell Lightroom to keep the current aspect ratio no matter how else you manipulate things with the Crop Overlay tool.
There's an apparent bug in the aspect ratio crop capability of Lightroom that you will at some point run into. While the Aspect ratio choice in the Crop Overlay options allows you to enter any ratio you want, there's no way to tell it to rotate that crop relative to the image. It always aligns the same direction the image does in terms of portrait versus landscape orientation. To elaborate, entering a custom crop aspect ratio of 3 x 10 will have the same effect as entering 10 x 3. Rather than one giving you a wider image and the other one a tall one, both will do the identical thing for any given image. Hopefully Adobe will fix this at some point.
There is a way to trick the aspect selection in the Crop Overlay tool into changing the orientation it thinks you want by dragging the handles in a specific way. The method works by taking advantage of the fact that the overlay will resize itself to stay within the image as you drag any of its corners. Once the overlay is small enough, you can reposition it and convince it to "flip" orientations by employing an odd sequence of mouse gestures. First, grab the upper left corner adjustment handle. Drag it into the center of the image. The crop selection will shrink to accommodate. With your mouse still held down, drag that handle to the left hand edge of the frame. As you do, the now smaller crop selection overlay will magically turn itself ninety degrees. Presto. You're basically drawing a "V"-like motion with your mouse cursor. Weird, but it does work. You may need to try this trick yourself to really understand it. Matt Kloskowski has a video on Adobe's site that shows him doing it. He doesn't really describe the aspect orientation flip, he just does it while talking about cropping in general, so watch closely. Note that this orientation "flip" can also occur if the aspect ratio is locked. So while the Lock icon will keep the same aspect ratio, it won't necessarily keep the same orientation.
Once you get the crop you desire, just hit the Enter key or click on the "Done" button on the bar below the image and the crop will be executed. Given that Lightroom is indeed fully nondestructive, while you may now only see the portion you selected to crop, rest assured that the entire original image is still there. All you have done is to tell Lightroom you don't want to see what lies outside your crop. Think of this as being at least somewhat like changing the Canvas size in Photoshop. You can select the Crop Overlay tool again to see the entire image again and adjust your crop if desired. There's also a "Reset" button at the bottom of the Crop Overlay options that will remove a previous crop entirely.
The Crop Overlay tool can also be used to rotate an image. With the tool active, click just outside any of the corner adjustment handles and drag in a rotating motion and the image will spin with the selection outline remaining stationary. I like the way Adobe implemented this feature. The Crop tool in Photoshop turns the selection boundary with the image standing still, forcing you to turn your head to see what things look like. Lightroom thankfully rotates the image and keeps the selection still so you don't end up with a crick in your neck after rotating a few images. There's also a slider in Lightroom with an accompanying numeric input box for the rotation angle in the Crop Overlay options area that works the same way.
An even better way to straighten an image in Lightroom though is to use the Straighten tool found in the Crop Overlay options area. It looks somewhat like a small carpenter's level and can be found just to the left of the rotation Angle slider. If you click on the Straighten tool and then drag over your image to draw a line the image will be rotated to make that line horizontal or vertical (whichever is closer) when you let go of the mouse. If you hold down the Alt key (Option key on OS X) Lightroom will kindly display a grid overlay aligned with your Straighten line to help you make sure you have the angle as you want it.
This article wouldn't be complete without mention of one more rotation option that doesn't entail the Crop Overlay tool at all. From the menu you can use Photo >> Rotate Left (CCW) or Rotate Right (CW) to easily rotate the image by ninety degrees in the selected direction.
Again, no matter what you do in terms of cropping or rotating your images in Lightroom, the underlying image data remains unchanged so feel free to experiment.
Update 6/27/2011 - Wow. Loyal reader CB wrote in to let me know something I never knew. Turns out you can quite easily change the orientation of the crop selection box by simply pressing the "x" key on the keyboard. What could be easier? Many thanks!