Photoshop
Interface
Performance Preferences
This set of preferences determines how Photoshop handles things like memory usage and image cache.
View a full-sized version of the Performance preferences or the CS3 version.
- Memory Usage
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Image processing requires a great deal of RAM (Random Access Memory). This option allows you to set the amount of RAM you want to allocate to Photoshop. You to either manually set a number for the maximum amount of your computer's RAM you'd like to allow Photoshop to use or to drag the slider to adjust this value percentage-wise. The default is usually 55 percent. More RAM allocated to Photoshop will cause it to perform faster but it may slow down other applications on your computer when Photoshop is active.
- Available RAM: Displays the amount of RAM your computer has.
- Ideal Range: This is the range in which Photoshop can function effectively.
- Let Photoshop Use: You can input the number of MB of RAM manually but it should be a value within the Ideal Range.
- Scratch Disks
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Scratch disks are different hard drives or partitions on your computer that Photoshop uses for memory when physical memory (your RAM) is full. An image in Photoshop can take approximately 3-5 times its file size. For instance, if your file takes up 10 MB of your hard drive, Photoshop could require 40 MB or more of RAM when working with it. As you work on multiple images or lots of changes and multiple layers, RAM requirements increase and Photoshop will begin to use your hard drive for virtual (rather than physical) RAM.
It is recommended that free space on your hard drive for the scratch disk equals at least the amount of physical RAM in your system. If you have 128 MB of RAM, you should have at least 128 MB on your hard drive for the scratch disk. The greater the RAM and free space, the better Photoshop performs. Photoshop can have up to four scratch disks. By default, Photoshop will use your Startup hard drive. If you plan on using Photoshop for a large file (i.e., print), or many smaller files at once, it might be a good idea to get a second (or more) hard drive(s) for your computer if your current system is low on resources. Ideally, running Photoshop on one disk drive, storing images on a second disk, and using a third one for a scratch disk will provide the best performance.
History & Cache
- Optimize Cache Levels and Tile Size for documents that are: (CS5)
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- Tall and Thin. These are files with many layers ("tall") and small image dimensions.
- Default. These are files with moderate dimensions and layers.
- Big and Flat. These files have few layers ("flat") but large dimensions.
- History States
- Each action you perform in a document is recorded in the History panel as a "state". This option sets the number of history states that Photoshop will record for each image. A larger number entered here will let you backtrack further (undo) to an earlier state but more memory is required.
- Cache Levels
- The cache is an area of memory Photoshop uses to store low-resolution versions of your images to help with screen updates or refreshes. A higher value will update the screen faster, but the image, as far as display is concerned, may be of lower quality. A setting of 1 is basically the same as no caching because Photoshop will store the full image size in the cache. Note that this does not affect the file in any way.
- Cache Tile Size (CS5)
- This describes the number of bytes that Photoshop stores at once. Referring back to the Optimize buttons mentioned above, a higher cache tile size is used for "big and flat" images while a smaller size is more appropriate for "tall and thin" images.
- GPU Settings
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The GPU (Graphics Processing Unit) settings let you enable or disable OpenGL drawing capabilities on your video adapter. From the Photoshop CS5 Help file: "OpenGL is a software and hardware standard that accelerates video processing when working with large or complex images such as 3D files. OpenGL requires a video adapter that supports the OpenGL standard. Your performance when opening, moving, and editing 3D models is significantly improved on a system with OpenGL. (If OpenGL is not available on your system, Photoshop uses software-based ray-trace rendering to display 3D files.)" OpenGL is also required for Animated Zoom and the HUD colour picker.
Our screen shot was taken on a computer equipped with OpenGL. If any performance problems occur, you can click the Advanced Settings button to adjust settings for memory usage and anti-aliasing. If no OpenGL graphics video card is detected on your system, the Enable OpenGL Drawing option will be greyed out as will the Advanced Settings button.
In CS3 Extended, the GPU settings contain only a checkbox labelled Enable 3D acceleration. When a GPU card is detected, this option can be turned on or off.
Description
In the Performance preferences only, there's a section at the bottom labelled Description. When you hold your mouse over any of the options, a description of that option will be displayed in the Description area.
Performance Preferences Summary
- Performance Preferences set options that affect how Photoshop performs in terms of memory usage, history, cache, scratch disks, and image rendering.
- Memory Usage allocates a specified amount RAM to Photoshop.
- Scratch Disks are areas of your hard drive(s) Photoshop uses for virtual memory when physical memory (RAM) is full.
- Optimize Cache Levels and Tile Size for documents that are: (CS5) lets you select a typical image type to determine optimum cache and tile size settings.
- History States lets you set the number of recent states (edits) stored for each image file.
- Cache Levels are memory settings affecting image rendering and performance.
- Cache Tile Size is the number of bytes that Photoshop stores at once.
- GPU Settings are used to enable/disable OpenGL drawing and provides advanced settings to optimize image rendering.
- The Description section provides additional details about any of the Performance options when you mouseover that option.
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