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This chapter is from the book

This chapter is from the book

Optimizing Photoshop's Performance with the Plug-Ins & Scratch Disks and Memory & Image Cache Preferences Settings

Photoshop handles memory very elegantly, but it doesn't know the memory and hard disk specs of your system. Therefore, the next two Preferences dialog boxes are where you find the real control—how to fine-tune Photoshop's performance. The following sections discuss the settings on the Plug-Ins & Scratch Disks Preferences page and the Memory & Image Cache Preferences pages.

Choosing Plug-Ins & Scratch Disks Preferences

The settings in the Scratch Disk area of the Plug-Ins & Scratch Disks Preferences page are probably as important in Photoshop as color settings are for the workspace. Photoshop needs hard disk space in which it saves history pieces, Clipboard pieces, multiple copies of an active file for Undo purposes, and more. If you do not give it enough hard disk space, your work could come to a grinding halt even with gigabytes of RAM on your system. The Plug-Ins & Scratch Disks Preferences page is shown in Figure 3.17.

Figure 3.17Figure 3.17 You can specify up to four temporary locations on your system's hard disk(s) where Photoshop can store parts of files, multiple undo images, and other things.

Let's get the trivial preferences here out of the way so that we can talk memory management with you:

  • Additional Plug-Ins Folder. Plug-ins, those third-party enhancers from Alien Skin, Andromeda Software, and others can be installed to Photoshop's Plug-Ins directory. Now, here's the catch: What if you also own, say, Painter and want to use the same plug-ins in Painter? No problem. You create a folder on one of your drives, plunk your third-party plug-ins in the folder, and then point Photoshop toward this folder as an additional place to look for plug-ins. To do this, you need to check the Additional Plug-Ins Directory option and then specify the plug-ins location in the Browse for Folder dialog box that appears. This way, Photoshop will go looking the next time you start it. Changes to folder locations for plug-ins don't take place until you restart Photoshop.

  • Legacy Photoshop Serial Number. Some plug-ins will not work without a legitimate Photoshop serial number. Well, the sequencing of the registration number changed back with version 7 of Photoshop, and this might keep third-party plug-ins from working. So, put in your registration number from a previous version of Photoshop if your plug-ins aren't plugging in.

Okay, memory management...

Choosing Scratch Disks Preferences to Dole Out System Resources

New users might be surprised to learn that Photoshop doesn't use that nice hunk of temporary space you set away for applications to use. Nope, Photoshop wants its own space that no other application's going to touch while it is running—and it wants it to be as large as possible. Adobe, like virtually no other company, knows how to handle memory. This means where other applications might gag and crash handling a 40MB image file, Photoshop can do it—if you set up memory and scratch disk allocation the way it wants.

As a rule of thumb, Photoshop wants to work with three to five times the size of a saved image file. This means that if you are working on a 15MB file, you need to have 45 to 75MB free of both scratch disk space and physical RAM. If you have less scratch disk space than RAM, Photoshop will not use any more RAM than it has access to scratch disk space. Therefore, if you have 1GB of RAM and have assigned Photoshop 200MB of scratch disk space, Photoshop will use only 200MB of that huge RAM amount you have installed.

You can specify up to four scratch disks. In the Scratch Disks area of the Preferences page shown in Figure 3.17, you can see that I specified two drives for scratch disk space. When the hard disks were partitioned, drive G (the First drive) was created to be used only by Photoshop. Hard disks are cheap—image work is much larger than it used to be—and I felt that 3GB was plenty of room in which Photoshop could play. The Second drive, drive C, is simply a drive with a lot of room on it.


Big recommendation here Windows ME and later versions defragment drives while you're not watching so that the drives are always optimized. This is not true on the Macintosh. Macintosh users should defragment and optimize their scratch disks regularly using a utility, such as those made by Symantec.

Beginning in 2002, both Windows and the Mac OS began to handle memory in similar ways. This means that the memory handling techniques you'll read about in the following section apply equally to Macintosh and Windows users.

Scratch Disk Assignment and RAM Requirements

Windows and the Macintosh dynamically resize the memory pool to allow applications to extend their use of RAM while you work. But it's still a good idea to devote hard disk space to as many drives as you can afford in the Plug-Ins & Scratch Disks page of the Preferences dialog box. Good candidates to which you can assign a scratch disk location are these:

  • A drive that has a lot of free space. I've gone overboard with my own system, but even 1GB is not unreasonable, and naturally, you get this space back after you close Photoshop.

  • A drive that does not use a compression scheme. Microsoft DriveSpace is not cool on the drive to which you assign the primary scratch disk. Compressed drives shouldn't even exist in 2004. Get a big hard disk instead of compressing.

  • A drive that has been defragmented. As mentioned before, use the Disk Defragmenter utility to optimize any drive to which you assign scratch disk status if your OS doesn't have native clean-up features.

Your first choice should be the drive that happens to have the most free, uncompressed space. If you have any other drives that have a lot of free space, you can assign them as second, third, and fourth drives. Photoshop honestly needs this kind of hard drive space to enable you to work quickly and flawlessly. You might even want to rethink running other applications while Photoshop is loaded to give maximum memory support to Photoshop.


Don't put a scratch disk on your C drive It is not a good idea to put a scratch disk on your C drive. Not only is this usually the drive where your operating system is located, but it's also where temp folders for other applications are placed. If you attempt to dynamically resize a space on a drive on Windows that's been assigned as a scratch disk, you will have system problems.

If you look at the Preferences dialog box again and click Next now, you see the Memory & Image Cache settings.

Setting Memory & Image Cache Preferences

Cache setting for images helps speed up their display in the same way that caching on your system helps speed up display of frequently used screen areas. The default Cache Levels setting is 4, and we see no need to change this because it is a good trade-off between snappy display and overall system performance. The Memory & Image Cache Preferences page for a Windows system is shown in Figure 3.18.

Figure 3.18Figure 3.18 Set the Maximum memory used by Photoshop to at least 96MB; 128 is better; and 256MB is better still.

Use Cache for Image Histograms in Levels is not really a preference you want to choose. We recommend that you leave this option unchecked. Even if you have the system resources to dedicate to caching histogram information, caching is performed on a sampling of pixels in the image, instead of all the pixels in the image.

The Available RAM you dedicate to Photoshop depends on how much total RAM your machine has. As you can see in the Memory Usage area of the Preferences page shown in Figure 3.19, the Macintosh computer in this example has 384MB of RAM. Adobe suggests at least 128MB of RAM for Photoshop, so math tells us that, in this example, about 50% of available RAM can be used by Photoshop, with a matching amount of scratch disk space.


Choosing the Efficiency display If you click on the triangle on the status bar (Mac: on the bottom scrollbar) and choose Efficiency from the pop-up, you will be in constant touch with how much RAM Photoshop is actually using (the indicator will read 100%). You will also be able to see whether Photoshop is swapping out to hard disk. If the Efficiency drops to 58%, for example, you should (1) save and close the file, and/or simplify it by merging unused layers, and (2) buy more RAM!


System resources If, by chance, your editing work exceeds the RAM and scratch disk space, Photoshop will begin to swap in and out elements it needs to complete your work, and this really drags your system down.

Also, you can set Maximum memory usage to 100%, but doing this is sort of a fairy tale. You aren't actually committing 100% of your system's resources to Photoshop; the Windows OS will not allow this. The OS needs resources of its own and will hang onto whatever it needs.

Strong hint: Buy RAM, and keep a large space on one or more of your hard disks free.

You actually decrease Photoshop efficiency as the RAM dedicated approaches 100%. This happens because the Windows system itself can use software caching, and Photoshop and Windows will fight over how much RAM is actually available.

Figure 3.19Figure 3.19 The Macintosh handles memory differently and much better for Photoshop users, with the introduction of OS X.

Let's move on to the next (and last) page in the Preferences, File Browser.

Choosing File Browser Preferences

The File Browser Preferences page, which is new in Photoshop CS, enables you to customize the functionality of the File Browser. The File Browser is very handy when you need to see thumbnails of the images within a particular folder, and it's especially useful if you need to sort through your images using keywords, for example. So, if you'll be using the File Browser, you'll want to understand your options on this Preferences page (see Figure 3.20).

Figure 3.20Figure 3.20 The File Browser Preferences page is new in Photoshop CS.

Check out the figure as we look at each of the options:

  • Do Not Process Files Larger Than. The default value of 500MB is quite large. The File Browser processes and generates a thumbnail of each of the images in the folder that you point the Browser to open. The more images you have and the larger those images are, the more processing power—and time—required of Photoshop. If you have images that are in the three-digit MB range, you might want to enter a smaller number like 100 or even 50.

  • Display. This option sets the number of most recently viewed folders that will appear in the Recent Folders section of the Location drop-down. You can enter any number from 0 to 30.

  • Custom Thumbnail Size. The default setting, 256, is good for most users. However, you might find a smaller or larger size more practical for your use. For example, say you have your screen resolution set to 800x600 but would like to see more thumbnails at one time in the File Browser. You could type a value smaller than 256, such as 128, thus making the File Browser generate smaller thumbnails so that twice as many could fit in the Browser preview window.

Within the Options field, you can select the following check boxes:

  • Allow Background Processing. Click to put a check in this box. The File Browser can be quite slow when processing a large number of files. So, unless you enjoy waiting for Photoshop to complete a task, having this item checked will speed up the process. Background processing employs extra processing power to pre-generate the cache information.

  • High Quality Previews. Again, processing power and time are the concerns here. If you prefer high-quality thumbnails and have a fast machine, we recommend leaving the default check in this box. Otherwise, if your machine bogs down when the File Browser is generating the thumbnails, uncheck this item for faster processing.

  • Render Vector Files. Check this item if you need to see vector image files, such as Illustrator files.

  • Parse XMP Metadata from Non-image Files. With this option checked, the File Browser will show a thumbnail of non-image files, such as text files, and enable you to edit the metadata. Unless you have a need for this option, leave the check box unchecked. That way, if the folders where you are browsing contain any non-image files, you won't be wasting processing power and time generating thumbnails of those files.

  • Keep Sidecar Files with Master Files. Photoshop gives you the choice of maintaining the photos of the passenger car of a motorcycle. Okay, not really. But maybe a brief explanation is needed here. A sidecar file is an .xmp or .thm file that is generated from another (master) file and is used to help other applications process the metadata associated with that master file. (For example, many digital cameras create a .tmb file when a TIFF file is created.) And because the File Browser enables you to move, delete, or copy files from within the browser window, you have a choice of whether you want those sidecar files to tag along with their master image file. We recommend that you check this box. After all, what good is a sidecar without a motorcycle?

Whew! Do you feel like you've been locked in a (Preferences) box for around a week? Okay, come out in the sunshine now. You've optimized all the base-level stuff in Photoshop, and now it's time to make your preferences in the working space. Make Photoshop's workspace truly your own.

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