Like a well-fed amoeba, the 2007 Adobe Photoshop has split in two, producing its own child, Adobe Photoshop CS3 Extended. Think of Extended as Photoshop heavy (as opposed to Photoshop Light); it's basically the same application with some extra capabilities and bundled scripts targeted at video postproduction tasks, 3D texture-map editing, and scientific image analysis. At about $300 more than Adobe Photoshop CS3, it is a significant upgrade decision--one which I'm not sure will entirely satisfy the relevant users.
Adobe seems to use Extended as a dumping ground for everything it considers "other." What else could explain a product that supports both DICOM image stacks and texture-map editing? Though it boasts some useful capabilities, Extended seems like a tentative, uncertain step toward addressing each segment of Photoshop's heretofore tangential users. It's Photoshop with multiple personality disorder: one scientist, one architect/engineer, and one game designer/video producer.
Furthermore, whenever a company draws a market segment line between two versions of a product, the placement of that line becomes somewhat arbitrary. In the case of Photoshop standard versus Extended, that fuzzy line cuts across its 32-bit high-dynamic-range (HDR) imaging support. The standard version has Merge to HDR, which allows you to take bracketed photos and combine them to attain a broader tonal range. But for HDR-capable brushes and support for adjustments like Levels, Hue, and Saturation, you'll have to bump up to Extended. Even there, the Magic Wand doesn't work in 32-bit mode (although, oddly, Quick Select works), nor do Curves and the new Black and White adjustments (you can still use the Channel Mixer, however).
Its new measurement tools, which let you drop counters on an image as well as measure and record the distance and angle between two points, are faster to use than previous manual methods, but they feel a bit undercooked--as if Adobe is waiting to hear from users before putting them back in the oven. For example, the count tool doesn't even let you change the size or shape of the markers it drops, or provide an option to let them scale when you zoom. Despite the many potential applications for recording color values in an image, the color sampler tool still only supports four data points, and you can't record the measurements.
In addition to the enhanced Vanishing Point capabilities in its cheaper sibling--the ability to create linked planes at odd angles--Extended allows you to measure the planes and angles as well as export the meshes to DXF or VPE (After Effects). You can import a few popular formats of 3D models and edit any embedded texture maps; there are some basic rotation controls, coarse rendering options, and some odd lighting presets (it will load lights from the file, however).
However, if Adobe intends this to be a useful tool for creating presentation materials using 3D objects--can you say Acrobat 3D?--it needs more high-quality renderers and light presets, plus better visual feedback as to whether you're manipulating the camera or the object. The cross-section view is nice, but a reference axis floating in the object space would be really helpful. You can apply filters to 3D objects via Smart Filters, which I have to admit is very cool for producing "artist's rendering" views of a model.
Extended also contains some refugees from the now-defunct ImageReady, including its frame-based animation tools. Adobe has expanded the animation to include a timeline for basic keyframing of video effects and individual frame edits; it's certainly no replacement for After Effects CS3 Professional, but will serve in a pinch. Though I can understand the development reasons behind splitting the motion capabilities into a separate package, it's a shame to deny Web or mobile designers the ability to, say, animate the movement of a drop shadow via the Global Light setting, unless they fork over the extra $300 bucks.
Though based on the veteran 10th-generation Photoshop CS3, Photoshop Extended feels like a version 1.0 product tacked on. If you have the budget and want to experiment with the new tools, it's certainly worth a try. But if you're looking for the same streamlined, high-productivity tools for technical analysis, 3D imaging, and video/animation that Photoshop brings to traditional imaging, you'll need to wait a version or two.