Using a Grey Card
Because a digital camera attempts to look (and adjust) images taking into account areas with 18% grey, the best way to make sure that this occurs is to have it in the picture to begin with. A variety of companies produce an 18% grey card. From solid plastic to folding cloth, these cards give you the ability to put a solid grey square into your image.
When you are working on a photo shoot, simply place the card into the scene, near the object that you will be photographing (in this instance, I have our model holding the grey card, as shown in Figure 4).
Figure 4 A model holding a grey card
Take a picture with the card in place, then proceed with your photo session. Once you have completed your photo session, select all of the images and drag them into Photoshop CS5.
Adobe Camera Raw will open all of the images in a strip to the left side of the screen, showing you the first grey card image in your series. Select the White Balance eyedropper at the top of the Camera Raw window and click on any area inside of the grey target (see Figure 5). You’ll notice that the color is automatically corrected to its best temperature and tint (see Figure 6).
Figure 5 Using the White Balance dropper
Figure 6 The White Balance calibrated image
Now it’s time to make sure all of the images that we’ve shot have the same color. Press Command-A (or Control-A on a PC), and all of the images in the strip to the left will be automatically selected. You’ll notice that the original image has more of a white border around itself, letting you know that this is the main image that is selected, and the one that you will be using for comparison.
At the top of the camera RAW window, you’ll see a Synchronize button (see Figure 7). Clicking on that will bring up a dialog box, allowing you to select which of the Camera RAW settings you would like to synchronize with all of the other images that are selected (see Figure 8). Clicking on the White Balance checkbox and clicking OK will automatically make all of these changes to the images, speeding up your workflow.
Figure 7 Synchronizing the Changes in Camera Raw
Figure 8 The Synchronize Dialog Box