Pros: Well-designed new interface; selective editing in Camera Raw; Collections in Bridge; improved dodge, burn and saturation tools; amazing content-aware scaling; interactive brush resizing.

Cons: Bridge still not well-suited for refined comparisons of images; no histogram display in Bridge; Loupe in Bridge still has technical problems; no dedicated straightening tool in Photoshop; Camera Raw selective editing doesn’t let you selectively apply white balance.

Score: 95

This is what a must-have upgrade looks like:

* New features you'll use regularly
* Fixes to old features
* Performance and stability enhancements
* Interface improvements (that don’t interfere with the stuff you already like)

Tick off every one of those points and you get Photoshop CS4.

Whether you’re a photographer, designer, special effects wizard, or any other kind of Photoshopaholic, this upgrade could have a bigger impact on your work life than a major upgrade to your computer’s operating system.

There are lots of things to explore in the standard edition of Photoshop CS4. I'll introduce you to the changes as you might encounter them in a typical photography workflow.

Bridge CS4
Bridge is a media browser bundled with all versions of Photoshop CS4. It lets you view thumbnails of media in a folder, including most popular video and animation formats. Within Bridge, you can view very large previews as well as thumbnails, sort and rate files, add keywords and metadata, and even copy and move files from place to place.

Not only is Bridge your starting point to find images you want to take into Photoshop (or any other Creative Suite application). It's also a good replacement for your operating system’s file management system when you're organizing images.

Figure 1. Bridge CS4 is the latest update to Adobe’s bundled browser. Like Photoshop itself, Bridge CS4 sports some big interface changes. Click the image to see a larger version.

Read about the welcome changes to Bridge CS4.

Camera Raw 5
If you shoot photos as information-loaded raw files, the next step in your Photoshop workflow -- after you’ve used Bridge to find a raw image you want to process -- is to open the image in Camera Raw. Like its predecessors, the latest version of Camera Raw is a plug-in that launches automatically when you open a raw image. For years, raw shooters have joked that Photoshop is more of a plug-in to Camera Raw, since they’ve been able to perform so much essential editing in Camera Raw. The new version 5 adds even more image editing functionality to Camera Raw.

Camera Raw retains its single-dialog interface with tabbed panels of controls, and it fits into your workflow just as it always has, although the Camera Raw dialog box has seen quite a few changes. There are new tools in the toolbar and new sliders in the Basic editing tab.

Figure 2. Camera Raw’s interface remains largely unchanged, but for a few tool additions. Click the image to see a larger version.

Read more about Camera Raw's improvements.

The App Itself
While Photoshop CS4 has a lot of important new features, you’ll first notice the interface. An Application Frame now encloses all panels and open documents. This single window with a gray background is intended to provide a unified working environment.

Multiple documents are displayed in a tabbed array, so you see one document at a time and switch to others by clicking their tabs. The document window is flush with the panel windows, and you can drag the border between to resize your document and panels simultaneously. Resizing the Application Window preserves the size of the panels while shrinking your document.

Figure 3. Photoshop CS4 defaults to enclosing your whole workspace within an Application Frame, which houses individual documents in tabs. Click on the image to see a larger version of Ben's extraordinary footwear.

The Application Frame includes a new Application Bar, which sits above the Control Bar and has buttons for some commonly used functions: launch Bridge; show Guides, Rulers, and the Grid; and zoom the current window. The Hand, Zoom, and new Rotate View tool are accessible from the Applications Bar, and a pop-up menu has options for tiling the currently open documents. I like the ability to show the same location in each document with matching zoom levels. You can easily switch back to a normal tabbed view at any time.

Adobe moved the Screen Mode controls from the main tool panel to the Applications Bar and changed them fairly dramatically. Full Screen mode now shows the current document on a completely black screen, with no interface of any kind. If you mouse to the left or right edge of the screen, the toolbox or tool panels appear, or you can go into Full Screen mode while preserving the menu bar.

On the right side of the Applications Bar is a pop-up menu for selecting any of Photoshop’s Workspaces. This is the same as using the Workspace controls under the Window menu.

At first, you may find the new interface cumbersome. For example, if you're used to floating windows, the tabbed interface can be a hindrance when you need to quickly copy and paste between documents. Also, the Application Bar takes up extra screen real estate.

If you just can't adapt, you can deactivate the Application Frame and Applications Bar to restore the interface to its more traditional arrangement. You’ll lose access to the full screen pop-up menu, but F still cycles through the different full screen modes.

However, it’s worth giving the new interface a try because it's such a clean environment for working. Photoshop is a panel-heavy program, a problem that Adobe has tackled in many ways over the years: customizable workspaces, the ability to hide unwanted features, dockable panels, and now the Application Frame. You might decide you want to use combinations of each of these.

Brush, Zoom, Zip, Pow!
Adobe has tweaked Photoshop’s Brush and Zoom tools to great effect. While you can still change brush size with the [ and ] keys, you can now interactively change brush size by holding down Control and the right mouse button under Windows (Control and Command on a Mac). With these modifiers held down, you simply drag the mouse to re-size the cursor. Photoshop shows the cursor in red, including blurred edges to represent feathering. By holding down the Alt or Option key in addition to the other modifiers, you can change the hardness of the edge by dragging.

Once you learn the modifiers, you’ll quickly adapt to resizing your brush while painting. It's a much easier method than using the keyboard.

With CS4, Adobe finally decided to leverage the power of the graphics processing units in almost all modern computers. In previous versions, when you clicked with the Zoom tool, Photoshop re-drew the image at the next pre-set magnification level. While the Zoom tool still works this way, you can also simply hold down the mouse button to see a smooth zoom in, with an accompanying pan to center the image around the Zoom tool.

In addition to looking really cool, this behavior makes precise zoom amounts much easier. At around 500% magnification, Photoshop begins superimposing a pixel grid over your image. This can facilitate individual pixel edits, but if you don't like it, you can deactivate the grid.

The improved zooming is also more accurate. You’ll no longer see jagged edges on high-contrast lines when zoomed to odd percentages.

If you zoom into a particular magnification, then hold down the H key and click with the Zoom tool, Photoshop zooms out to fit to window, and a small rectangle appears next to your cursor. This indicates the crop of your last zoom. Position the rectangle somewhere else on your image, click the mouse, and Photoshop automatically zooms that area in to the same magnification. While it's an interesting addition, I don't use it much in real-world work. However, different users work in different ways, so some of you might find it more compelling.

If you release the mouse button while quickly panning over a document, the image zips across the canvas, then slowly coasts to a stop. It's a little more effective with a stylus and tablet than with a mouse, though not necessarily any easier than using scroll bars.

If you use a tablet, you’ll love the new Rotate View menu, which lets you rotate the view of your image within the document window. It's not a rotation of the image on the canvas, but simply a virtual equivalent of rotating your computer monitor. I’s like rotating your drawing surface so you can more easily draw along a particular axis, rather than drawing at 90° angles relative to the sides of the tablet. Double-clicking on the Rotate View tool returns the image to its normal orientation.

Corel Painter has had this feature for years, and I'm happy to see it in Photoshop. Rotate View is the only feature besides Zooming that's GPU-accelerated. It’s great to see Adobe taking advantage of this extra processing power; it bodes well for future innovation and acceleration. Your graphics card must be OpenGL-compatible, but most GPUs are these days.

More Tool Changes
The Clone Stamp and Healing Brush tools have new behaviors. Where previous versions showed the size of your cursor, CS4 shows the image data that will be cloned into the area where you’re painting. It's an on-the-fly preview of your cloning efforts before you ever lay down a stroke.

Adobe also improved the Dodge, Burn, and Sponge tools in ways that are difficult to describe but easy to feel. Perhaps the best way to describe the changes is that the new tools are not as blunt as before. As you dodge and burn, Photoshop does a better job of maintaining the original color, and your strokes don’t become over- or underexposed too quickly.

Because the Dodge and Burn tools are destructive, many people prefer to use a non-destructive approach built around Adjustment layers. However, the improved Dodge and Burn deserve a second look. (You can always use them on a duplicate of your image layer.)

In Photoshop CS3, Adobe introduced a new Black and White Adjustment layer that let you click and drag within an image to tone specific colors lighter or darker. Happily, Adobe has added this same functionality to CS4's Hue/Saturation and Curves Adjustment layers.

Easier Adjustments
Photoshop’s Layer Masking interface is greatly improved in CS4. Previously, when you added an Adjustment layer -- a non-destructive layer that lets you apply a specific image-editing adjustment to all underlying layers -- you had to configure the adjustment's parameters in a modal dialog box. To change those parameters later, you had to double-click on the Adjustment layer and re-open that modal dialog box.

Those bad days are gone, thanks to the new Adjustments panel. Just click on the layer in the Layers panel, and its controls appear in the Adjustments panel.

Figure 4. The new Adjustments panel is a non-modal interface for all of your Adjustment layer chores.

There's a large assortment of presets for each adjustment type. When no Adjustment layers are selected in the Layers panel, the Adjustments panel shows a selection of Adjustment layer types. Click on a type of Adjustment layer and its presets appear. Double-click on that preset and Photoshop adds a new Adjustment layer to your layer stack, pre-configured according to the preset.

Buttons at the bottom of the Adjustments panel are shortcuts to hiding and showing layers, and to grouping Adjustments layers with underlying layers to constrain their effects.

Adobe has added the Vibrance adjustment from Camera Raw to Photoshop itself, so you can now do a Vibrance edit as an Adjustment layer or as a normal destructive edit.

Keyboard Shortcuts
The big problem with major interface changes is, of course, change. Once you’ve learned a specific method for doing things, alterations to panels or tools can throw a wrench into a smooth workflow. So do yourself a favor: If you’re in the middle of a job, or about to take on a high-pressure assignment, don’t switch. Instead, wait until you have a few hours to get familiar with CS4. It won’t take long, and many of the changes are worth exploring, rather than just deactivating.

However, there are some keyboard shortcut changes that may annoy you even after the initial adjustment period. Because Adjustment layers are no longer implemented in self-contained dialog boxes, the keyboard shortcuts you once used for those controls may not work anymore. For example, changing channels within the Levels adjustment using Control/Command-1, 2, or 3 no longer works because some of those shortcuts have other functions within the application.

There are some ways around the broken old shortcuts, which you can read about in a very handy post from John Nack.

On the positive side, Photoshop now supports the standard Mac and Windows keyboard shortcuts for switching between documents. And while the zooming keyboard shortcuts remain the same (whew!), Adobe has added Control/Command-1, which sets the zoom level to 100% and makes Photoshop zooming behavior consistent with the rest of the CS4 suite.

There’s also an important modification to Photoshop’s toolbox shortcuts. In previous versions, you could select tools through keypresses -- B to select the Brush, G for the Gradient tool, and so on. CS4’s tool shortcuts are spring-loaded. For example, if you’re painting with the Brush and need a quick dodge, you can hold O to activate the Dodge tool. After painting your dodge strokes, let go of the O key and you’ll be back to your Brush. And since you still have the spacebar for panning, and several commands for zooming, it’s as if you have four or five tools in your hand at once.

One other keyboard change really made me happy: You can delete a layer by selecting it in the Layers panel and hitting the Delete key. You may very well find changes you’ve been itching for sprinkled through the program.

On page 2, Ben demonstrates CS4's jaw-dropping new tool with before-and-after images.

Easier Masking
One of the benefits of Adjustment layers is that they include a built-in mask you can use to constrain their effects. In previous versions of Photoshop, you controlled layer masks through the Layers panel, painting directly into the masks to constrain an Adjustment layer. This behavior is the same in CS4, but now Photoshop also has a Masks panel that gives you shortcuts to the Color Range and mask edge controls.

To use the Masks panel, first select an Adjustment layer you want to apply a mask to. Click the Mask panel's Color Range button to bring up Photoshop’s standard Color Range dialog box. Color Range has been slightly upgraded, with additional options for controlling the boundaries of the color selection range. With the new features, you can now create more subtle transitions in color range selection.

After configuring Color Range, Photoshop automatically creates a mask and attaches it to the selected Adjustment layer. A feather slider lets you soften the edges of all boundaries within the mask, while the Density slider lowers the mask's opacity.

Figure 5. The new Masks panel is a one-stop shop for all of your selective color Layer Masking needs.

If you prefer to work with vector masks, you can click on the Pen tool in the Masks panel to access Photoshop’s normal vector-masking functionality.

Aside from the improvements to Color Range (which is also accessible from the Select menu), the Masks panel doesn’t add any functionality. Rather, it consolidates many automatic masking operations you might normally use into a single panel. If you prefer to paint masks by hand, you’ll still use the old method.

To b honest, I didn’t even look at the masking panel until weeks after I’d started using the CS4 beta, because I can access my preferred masking functions as I did in CS3. While I doubt I’ll become a Masks panel devotee, it's good for casual maskers and beginning maskers who want to start using Adjustment layer masks but aren't sure how.

Improved Features
Many of Photoshop's older features have received a new shine in CS4.

The Auto-Align and Auto-Blend features (released in CS3) are better. Where most users will notice the difference is in the Photomerge script, which stitches multiple images into a seamless panorama. While the CS3 stitching was excellent, the new version has smoother color transitions from one image to another. CS4 also does a much better job of correcting vignetting and barrel or pincushion distortion, further reducing color discrepancies across individual images.

The addition of depth-of-field stacking has improved Auto-Blend layers. You can shoot multiple frames that are each focused at a different distance, and Photoshop will merge all of the images, pulling the in-focus areas from each one, to create an image with very deep depth of field.

For this feature to work well, you must invest time and effort in set-up. A tripod is a must, and a moving subject won’t work. Even landscapes with very deep depth of field may not be practical, as blowing trees or moving clouds will ruin the results. For macro shooters, though, depth-of-field stacking is a great addition.

How Do They Do That?!
Perhaps the most impressive new feature is Content-Aware Scaling, which changes the proportions of an image without altering the subject matter.

Consider this original image (click it to see a larger version):

To place this image in a layout that required a different aspect ratio -- say, a square - I could scale it horizontally, but then the motorcycles would be distorted:

Click above to see a larger version.

With the new Content-Aware Scaling command, I can resize the image to a square, yet Photoshop doesn’t scale the motorcycles. Once I choose Content-Aware Scaling from the Edit menu, handles appear on the edges of my image, as if I were using the Transform command. I drag these to resize the image and Photoshop does the rest. There’s no need to tell it what subject matter to leave as is. The software figures that out on its own, as you see here (click for a larger version):

You can also use Content-Aware Scaling to scale up. While the results are still impressive, you’ll probably see a little more distortion of your subject matter.

This incredible technology, one of the most remarkable Adobe has ever produced, will be very useful for creative professionals of all stripes.

More Bits and Other Enhancements
In an upgrade this substantial, it’s impossible to include every addition and tweak, but here are a few more worth mentioning.

Windows Vista users can run the program in 64-bit. It doesn’t boost performance, but it lets you take advantage of colossal amounts of RAM. That's handy when you work on images greater than 4GB in size. While Mac OS X 10.5 (Leopard) supports 64-bit processing, Apple decided not to make the promised infrastructure changes necessary for Adobe to port Photoshop, so Adobe can’t be blamed for this omission.

Smart Objects (Photoshop’s mechanism for working non-destructively with raw files) have jumped a few IQ points. You can now apply scaling and geometric transformations to them, still in a completely non-destructive manner.

The Print dialog now shows out-of-gamut colors, and if you’re a Mac user, Photoshop now supports 16-bit printing. (Whether sixteen-bit printing is actually useful is another story, and one I hope to cover soon.)

Missing in Action
A few features have fallen by the wayside in CS4. The Extract filter is gone, as are the Picture Package, Contact Sheets, and PDF Presentations features. I never found the Extract feature especially useful as a masking tool, and as for the others, the Output module in Bridge CS4 can perform similar functions. However, it only outputs PDF, whereas Picture Package and Contact Sheets could create Photoshop documents. These are unfortunate omissions, and I hope Adobe sets things right in a future update.

In the meantime, you can use the old Picture Package and Contact Sheet plug-ins with the new version.

Also missing is any kind of local help system. Instead, Help is only on the Web, which means you must have an Internet connection to use it. I’m often away from an Internet connection, or limited to a slow connection, and I hate to think that means I can’t get answers when I need them.

Worth Every Penny
Buying Photoshop CS4 new costs $699. Owners of Photoshop CS, CS2, and CS3 can upgrade for $199, a great price for the new features. The upgrade costs $599 when you move from Photoshop 5 or 6, but you’ll also get the features added in CS, CS2, and CS3, and you’ll open the door to an entirely new workflow in Bridge.

Photoshop CS4 is a very impressive upgrade. Adobe has improved the interface without making the transition uncomfortable (and while preserving your ability to remained with the old interface), and has added important new features and updates.

Photoshop is not perfect. There’s still no easy-to-use straighten tool; there’s no way to tell why some features go in the Automate menu and some in the Scripts menu, which can make it difficult to remember where you found a feature; Bridge still lacks a histogram display; and there are other minor annoyances here and there.

But make no doubt about it: Photoshop CS4 is far and away the best image-editing tool around, whether you're talking about ease of workflow or editing and adjustment power.