The Bridge and Its Slippery Cache: Adobe Photoshop CS4 One-on-One

by Deke McClelland

This excerpt is from Adobe Photoshop CS4 One-on-One. How can you master the fundamentals of Photoshop CS4, with all of its incredible features? Deke McClelland's proven One-on-One learning system offers step-by-step tutorials, five hours of DVD-video demonstrations, and hands-on projects to improve your knowledge and hone your skills. Read about features such as Photoshop's new Adjustments panels in the book, and see how they're used first-hand in the video. The combination is uniquely effective.

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In many ways, the Bridge behaves like your operating system's desktop-level file manager (called Windows Explorer on the PC and the Finder on the Mac). For example, if you click a thumbnail's filename, the Bridge invites you to enter a new name. Choose FileNew Folder to create a new folder. Press the Delete key to toss a selected image in the trash. Through it all, the Bridge magically tracks your changes, never once asking you to save your work.

This may lead you to believe that every change you make is permanent and will be recognized not only by Adobe applications but also by the operating system and other programs. But some actions are recorded in ways that only Adobe's programs can recognize, and sometimes even they ignore them.

For the record, here are some permanent changes you can make in the Bridge that all applications will recognize:

  • Dragging a file from one folder to another

Other changes are permanent, but they are written in such a way that only Photoshop and other applications that support Adobe's XMP (Extensible Metadata Platform) protocol recognize. If an application does not recognize a particular XMP tag, the change is ignored. Such changes include:

  • Custom Camera Raw settings

The final variety of changes are temporary. The Bridge saves these to proprietary files called caches:

  • Stunning high-quality thumbnails

Although permanent and XMP changes are 100 percent safe, sort order and thumbnails are maintained only if you move and rename files and folders inside the Bridge. This is because the Bridge tracks temporary changes based on the path, or specific location, of a file. If that path changes even slightly without the Bridge knowing about it—say, if you rename files or move them from the desktop—the program loses track of the files and the information is lost.

It might seem a tad fastidious to worry over such quick and invisible changes. It takes only a moment for the Bridge to draw a single thumbnail. But transfer a folder containing hundreds or even thousands of images to a CD or DVD and those moments can add up to a massive delay.

What's a savvy user to do? Tell the Bridge to stop hoarding centralized cache files deep in the system level of your computer and instead save them in the same folder as the images themselves. This way, the cache files stay with their images no matter what you name a folder or where you move it.

If you used the previous version of the Bridge, I recommend that you search your computer's main hard drive for a folder called Bridge CS3 that resides in an Adobe folder. Inside that, you should find a subfolder called Cache. Check its size. In the case of my MacBook Pro—a notebook with limited hard drive space—this folder weighed in at 4GB. If you're done with Bridge CS3, you're done with that folder. Throw it away and regain a lot of space.

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