Insider Info: GPU acceleration in Photoshop CS4

There are plenty of great new features in Photoshop CS4, but one thing that has really been hyped about the release is that the whole of Creative Suite 4 is the first application of its kind to take advantage of the power of native GPU acceleration. But if that means nothing to you, then we’ll explain exactly what GPU means and what extra features you gain as a result.

First things first, it helps to know what a GPU actually is. It stands for graphics processing unit. The GPU either sits on top of the video card or will be integrated directly into the motherboard – what you ideally want is the former. With Photoshop CS4 being such a resource-hungry application, by making use of the GPU and taking the strain off the CPU, you get better graphics and faster workflow. You can run Photoshop CS4 without having a dedicated GPU, but it does unlock added features and speed. In order for Photoshop to access your GPU and give you these benefits, then your display card must have a GPU that supports OpenGL, have 128MB RAM and a display driver that supports both OpenGL 2.0 and Shader Model 3.0.

If you have CS4, it’s easy to find out if you have a compatible GPU or not by simply going to Photoshop>
Preferences>Performance and looking in the GPU section, which will be greyed out if you can’t access the functions. Of course, you’ll find out soon enough anyway, as soon as you select the Rotate View tool and it won’t let you do anything! If, however, you want to know if your video card is supported before investing in Photoshop, then there is a full list of tested cards on the Adobe Knowledge Base (some cards not on the list may also work, but they haven’t been tested for compatibility) at
http://kb.adobe.com/selfservice/viewContent.do?externalId=kb405711&sliceId=1. Make sure that whatever card you have, you have got the latest driver, which you can check on your manufacturer’s website. In order to check what card you have installed, on a Mac you need to go to About This Mac from the Apple menu, then hit More Info to open the System Profiler. From here, select Graphics/Displays to see everything you need to know about your GPU setup. On a PC, you will find this information over in the Device Manager, which is accessible from the Control Panel.

If you don’t have a supported card, you’ll either need to upgrade to one that is supported (see the boxout for our recommendations) or make do without the extra features and speed.

So what does GPU acceleration actually mean for Photoshop CS4? Quite a lot, actually. For a start, everything works faster, and this is especially noticeable when you’re panning or zooming your way around large images. The Zoom tool is instantaneous, with no lagging, and completely smooth no matter how close you get. When you get to 500 per cent, you can get right down to a pixel-by-pixel view with no bleeding between the pixels – this pixel grid is perfect for extremely precise editing.

Pixel grid: When you zoom in over 500 per cent (and up to 3,200 per cent), you will see a pixel grid, giving you crisp separations between individual pixels for incredibly accurate editing

A new function is the Birds-eye View. If you’re zoomed into an image, you can hold down H and click with your mouse to zoom right out. Reposition the viewing rectangle and you’ll automatically zoom back into the new position, which is simply brilliant for fast navigation.

The Rotate View function is fantastic – a compass comes up on-screen and you can literally pull the image in any direction to spin it, without any need to enter an exact rotation angle as before. Similarly, the Hand tool has been updated with the ‘flick pan’ ability, where you can drag across the image and it will then pan in real-time in any direction you want.

Fluid rotation: The rotation compass lets you drag an image in any direction smoothly

There are plenty more advantages, especially if you are going to be using the 3D functions, as the GPU acceleration really does make things a lot quicker and easier here. It’s worth the video card upgrade if you’re shelling out for CS4.