Plug-Ins and Scratch Disks in Photoshop

Plug-ins and scratch disks are a couple of unrelated options combined in a single dialog box. Briefly, plug-ins are mini software programs that add features to Photoshop. Scratch disks are free areas on your hard drive(s) that Photoshop uses as virtual memory when it is short on RAM. Read on to find out more.

Plug-ins
The Plug-Ins folder is where Photoshop stores all your filters and other plug-in add-ons. A default folder is created when you install Photoshop. Photoshop allows you to specify an additional folder to search other than its own Plug-Ins folder. This additional folder may come in handy if you want to keep your third-party add-ons separate from Photoshop’s native plug-ins. An auxiliary plug-ins directory (not nested within Photoshop’s own Plug-Ins folder) can simplify managing those extra filters, and you can turn off their use (potentially speeding up Photoshop’s load time) by deselecting the Additional Plug-Ins Folder check box in this dialog box. You can also use this option when you have some plug-ins installed for another application and want to share them with Photoshop without having to make extra copies in your Photoshop Plug-Ins directory.

To activate a new plug-ins directory, select the Additional Plug-Ins Folder check box and then click the Choose button. In the dialog box that appears, navigate to the folder you want to use and select it. Click OK. You then need to exit Photoshop and restart the program to activate the new directory.

If you have a plug-in or folder you’d like to deactivate, use a tilde (~) as the first character of the plug-in or folder name. Photoshop will ignore the plug-in(s) or folder(s) specified. Just remove the tilde from the name to activate the plug-in or folder. This can come in handy if you are having a program glitch and want to deactivate your plug-ins to troubleshoot whether or not they are causing the problem.

Scratch disks
Scratch disks are areas on your hard drive that Photoshop uses to substitute for physical RAM when you don’t have enough RAM to work with the images you have opened. Scratch disks are no replacement for physical memory, but there are many times when Photoshop will need them, even if you have huge amounts of memory.

Photoshop uses your startup drive (the drive used to boot your operating system) as its first scratch disk by default. That may not be the best choice because your startup drive is usually pretty busy handling requests of your operating system and, if you’re running Windows, requests for Windows’ own virtual memory scheme (your so-called swap file or paging file). Ideally, your scratch disk(s) should be a different hard drive and, preferably, the fastest one you have available.

If you have more than one hard drive, choose one other than your startup drive as your first scratch disk. Select your fastest drive; for example, select a FireWire (IEEE 1394) or USB 2.0 drive over one using the original, slow, USB 1.1 connection. If you have an Ultra-DMA EIDE drive or, better yet, a SCSI drive, use that. Although Ultra-DMA drives have transfer rates that rival even the speediest SCSI models, SCSI can be better because the SCSI bus is designed for multitasking. You’ll often get better performance than with an EIDE drive that shares one of the two EIDE channels with other devices.

If you don’t have a second hard drive, you can improve scratch disk performance by creating a partition on an existing drive for use as a scratch disk. Remember to keep the scratch disk defragmented (that is, with the files all organized together on your hard drive) by using your favorite defragmentation utility.

Adobe changed the format for serial numbers with Photoshop 7, and if you have old plugins that require a valid Photoshop serial number, you can enter the serial number from an older version into the space provided in this dialog box.