Join Taz Tally for an in-depth discussion in this video Managing your memory for optimization, part of Photoshop CS3 Color Correction.
- [Narrator] In this section, I'd like to talk about setting up memory in Photoshop, 'cause Photoshop is such a memory intensive application that managing it becomes very critical, particularly when you're working with large color images. So the memory allocation section is in the preferences, which in the Macintosh it's underneath the Photoshop or application menu in preferences, and in Windows it was underneath the edit menu. And you can just come down and choose performance. It's not called memory, it's called performance. And it's a great title for it, because this really does, how you manage your memory really has a lot to do with how well Photoshop performs, how quickly it works.
Now, basically, there's three types of memory that Photoshop uses. The first is RAM, or random access memory, and basically, you can think of RAM as being like your desktop workspace. The more RAM you have, the more workspace that you have to work on, therefore the faster you can work, and, or the more projects you can work on a one time. Now Photoshop on both Mac and Windows uses dynamic allocation of memory. What that means is that Photoshop will take up only the amount of memory that it needs at any given moment, so that when you open up Photoshop, it's using a minimum amount of memory, but as soon as you open an image and start working on it, it'll take up more memory.
For those of you who remember the Macintosh in system nine, you actually had to select an application when it wasn't running, do a command-I, and then assign memory to it. Well that's no longer true. The Macintosh is more now like Windows that has had dynamic application memory for quite a while. Photoshop will take up more and more memory. What this first dialogue box portion shows you here is how much on a percentage basis of whatever ram is currently available Photoshop will have access to use. The number that you see here is in thousands of megabytes, also known as gigabytes.
So this is 3,072 megabytes, or three gigabytes. And then, Photoshop gives you kind of an ideal range of what it would like to have access to use. So between 1,689 and 2,200. Between 1,500 and two gigabytes, basically. And then, this percentage of number right down here in megabytes is set at about 70 percent in this particular case. And notice that we're well between these two numbers. You want to have at least a bare bones minimum of one gigabyte of available RAM for Photoshop to use.
And really, really, what you want to have for working on most images is two gigabytes of RAM for Photoshop to use. There's actually a complicated formula. There's a white paper on the Adobe website that describes in detail the complexities of how RAM is allocated in Photoshop. And you can read that if you want to, but when you get done with the end, you're going to come in here and assign two gigabytes of RAM. So that's really my recommendation. You want to have at least one, but you really ought to have two gigabytes. So whatever amount of RAM it takes for you to have on your machine that allows you to assign at least two gigabytes for Photoshop, come in here, and then adjust this so that you have at least two gigabytes available.
But my strong recommendation is generally don't go above about 70 or 75 percent. Why? Because your operating system needs memory as well, and you never want your operating system and Photoshop to be running into each other and competing for the same RAM. So never assign anything more than about 75 percent, but have enough so that you can have at least two gigabytes of RAM for Photoshop to work with. And it's true, the larger the files that you work on, the more gigabytes of RAM that you're going to want to have, but if you have at least two gigabytes of RAM, and you're working with eight by 10 300 pixel print images, you're going to have plenty of RAM assigned for Photoshop to use.
The second level of memory that Photoshop uses is called history and cache. Now if RAM is your desktop workspace that you have to work with, the cache is the portion of that RAM that is used in any given moment to recall the very latest thing that you did. That's what cache is. And then, history state is storing the last x number of things that you've done somewhere in memory. How many history states you store depends upon this menu that you have here. The default is 20. If you're working on an image, and applying edits to your image, and you find that you need to step back more than what Photoshop is storing for you in the history state, you can come in here and assign more history states, and then Photoshop will store that.
Now Photoshop is going to use scratch disc space, as well as RAM for managing the history states and the cache levels. So the more history states you have, the more cache levels you have, the higher the cache level, the more RAM and scratch disc space you want to have. We'll discuss scratch disc space in just a second. And that's fine. Have as many history states as you need, but don't have any more than what you actually want to have, or you need to have when you're working inside of your files on a regular basis. If you are working on a project that you know you're going to be doing lots of editing and have lots of variations of a file, then for that particular job, you may want to come in here and raise the number of history states.
Once again, provide as much RAM as you possibly can. RAM is cheap. It's a lot cheaper than time that we have to spend waiting for Photoshop to perform things. Cache level actually does use a portion of RAM, and my suggestion is set the cache level up at eight. When you set your cache level up to eight, which is the maximum, Photoshop can store the maximum amount of information of the most recently used item, such as the last view or the last layer that you were working on. The only time you might want to lower the cache level is if you're using a Wacom, a pen tablet, and the pen tablet is acting a little slow or squirrelly, sometimes having a large cache level will interfere with that.
So you might want to lower that if you have that problem with your pressure sensitive tablet. And then, finally, scratch disc levels. This is a critical memory variable to pay attention to. And first, what is scratch disc space? Well, if RAM is your desktop workspace, scratch disc is working in storage. It's working off of your hard drive. It's kind of like you've got your desktop table, and then you've got your file cabinet, and your file cabinet is where you store things, but once in a while you need that extra space, so you work on top of your file cabinet as well.
That's scratch disc. It's slower, it's kludgier, but it's an important aspect of memory to have, because no matter how much RAM you have, Photoshop will indeed use scratch disc space in order to store various portions of your image or project that you're working on. How do we manage scratch disc space? Well, the best way to manage scratch disc is to have free and clear space for Photoshop to swap files back and forth from, and the easiest and the best way to do that is to have a separate volume that you don't store anything on.
Best of all possible worlds is to have a separate hard drive installed internally in your desktop or tower computer, and then assign that as your scratch disc as you have here. By default, your computer will use the boot drive, which on a Windows machine is the c drive, and on Macintosh is the drive that comes up first in the upper right-hand corner of your desktop. In this case, it's the Macintosh HD. It will use that by default. And notice what I've done here is I've created a separate hard drive called scratch. And you do this by reformatting your drive or putting in a separate drive, and that's the easiest thing to do.
If you're working on a laptop and you can't have more than one drive, then you can reformat your drive and create a separate partition, a hardware partition to assign it to. Easiest thing, just put in a separate hard drive, and just assign that as the scratch disc here. But just putting in the hard drive doesn't do it. You must come in here and check this check-box, and then click OK in the upper right-hand corner. And then, in order to activate that new scratch disc, you'll have to quit Photoshop and then relaunch it. It won't access the new scratch disc until you actually quit Photoshop. There's the three portions of memory that you need to pay attention to.
Just to review, at least two gigabytes of RAM for Photoshop to use. Never go above about 70 or 75 percent, so that your operating system has plenty of RAM to work with. Your history states and cache. Cache uses a portion of the RAM that you have for storing the most recently used item. Keep this at eight as a general rule, unless you're working with a pressure sensitive tablet. Your history states, have as many history states as you need to work with, but no more than what you need to. Start with 20, and then go above if you need to. And finally, scratch disc. A separate volume that Photoshop can swap image data back and forth from free and clear, and not run into any problems.
There we go. So that's setting memory inside of Photoshop.
- Setting up Photoshop CS3 for color correction
- Managing images with Bridge CS3
- Understanding color image fundamentals
- Evaluating images quickly and accurately
- Determining whether to correct or adjust
- Evaluating and fixing physical characteristics
- Fine-tuning brightness and contrast
- Proofing and gamut testing