Adjustment layers have long been the tool of choice for nondestructive editing, though they weren't especially easy to find, nor were their presets. Now adjustment layers take centre stage in their very own panel, which not only makes them easier to find and use but it prevents images from being obscured by dialog boxes.
Also new are 'on-image' adjustments for the Curves and Hue/Saturation adjustment layers. Instead of making a selection, you can apply the adjustment to a specific tonal range by clicking on the image and dragging with your mouse. You'll also find a new Vibrance adjustment layer which will make your colours pop without damaging skin tones (it has more effect on brighter colours and less effect on light colours, like skin).
The new Masks panel also makes layer masks easier to find and a bit more friendly. After you've made a selection you can create a mask from the panel and feather it with a handy slider. Adobe also added buttons for Refine Edges and Color Range functions for more mask tweaking.
Using the simplistic controls of Free Transform with the revolutionary new seam-carving technology under the hood, Photoshop analyzes your image and alters unimportant areas, like the ground or sky, while leaving the important parts intact. Affectionately referred to as CAS, it works on image layers and selections in RGB, CMYK, Lab, and Grayscale color modes at all bit-depths (bit-depth refers to the number of colour values a channel can contain).
But does it work perfectly? No. You'll see artifacts in some images, which means you've got to be really picky about when you use it (no tight portraits), and how much scaling you do (very little). You can, however, give the tool a little help by protecting your subject with an alpha channel first. Still, this function has many practical uses like fitting an image into a small space without cropping, prepping an image for a certain output size when the original aspect ratio isn't quite right, and more.
Enhanced color and painting tools
Graphic designers will appreciate Kuler integration, an amazingly useful, online community-driven colour theme generator. If you get stuck trying to choose a colour palette for your design, pick one from the growing number of shared themes (feel free to join the fun and upload your own). Retouchers will be happy to know that the Dodge, Burn, and Sponge tools--long considered too destructive for use directly on an image -- have been re-engineered to intelligently preserve colour and details, and the Clone Stamp and Healing brushes now show a live preview -- inside the brush cursor -- of the sample area you're about to apply. You can also resize any brush-based tool by Control-Option-dragging or change the hardness by Control-Option-Command dragging.
The new adjustment brush in Camera Raw 5.0 lets you selective paint adjustments.
Camera Raw 5.0
The newest version of the Camera Raw plug-in sports major improvements like the ability to edit selectively using an Adjustments Brush, apply nondestructive Gradient Filters, and perform post-crop vignetting.
Selective adjustments are incredibly easy to use; just select the Adjustment Brush by pressing K on your keyboard and you'll see the same set of slider-based adjustments appear on the right side of the window as you do when you first open Camera Raw. After you brush across your image to apply the adjustment, a green push-pin marks the area. Behind the scenes, Camera Raw creates a mask that hides the adjustment from the other areas of your image.