White Balance tool
The White Balance tool is located near the top of the Basic panel (Figure 6.25). You can activate the tool by clicking it (or press ), which unlocks the tool from its location and allows you to click anywhere in the image to set the white balance. The floating pixel magnifier provides an extreme close-up of the pixels you are measuring, which can really help you select the correct pixel reading. As you hover over an image, you see the RGB readout values for the point in the picture beneath the cursor (Figure 6.26). These RGB readings are shown as percentage values and can help you locate and check the color readings (if the RGB values are all close enough to the same value, the color can be regarded as neutral). If the Auto Dismiss option is disabled, you can hold down the key and continue clicking with the tool until you get the right balance setting, while the key can be used to cancel and return the tool to its normal docked position.
- To make a white balance adjustment, select an area of the picture that should be neutral in color (but not a bright white area of the photo). The light gray stones in this picture are a perfect spot to sample from. If the Auto Dismiss box (circled) in the toolbar is checked, the White Balance tool automatically returns to its docked position in the Basic panel. If the Auto Dismiss box is unchecked, you can click and keep clicking with the White Balance tool until you are completely satisfied with the white balance adjustment that you have made.
- The Show Loupe check box allows you to toggle displaying the loupe that appears just below the White Balance tool cursor. You can adjust the loupe scale setting by dragging the slider next to the Show Loupe item in the toolbar. This slider adjusts the sample grid pixel size, and dragging the slider to the right will increase the number of pixels used when sampling a white balance point measurement. Increasing the pixel sample size can be beneficial if you want to aggregate the pixel readings more, such as when you’re sampling a really noisy image and you don’t want a white balance measurement to be unduly affected by the pixels that contain color noise.
White Balance corrections
In most shoot situations, once you have found the right white balance, all the other colors will tend to fit into place. The As Shot camera Auto White Balance setting may do a good job, but it really depends on the camera you are using (Figure 6.27). Even the best camera won’t know how to handle every lighting situation it meets. In Figure 6.28, we see a scene where there were mixed lighting conditions. This photograph could be processed for either the daylight lighting or the tungsten lighting indoors, and each could be said to be correct. In situations like this you can’t always rely on the camera’s Auto White Balance setting; you have to decide for yourself which setting looks the best. This is where the White Balance tool can come in handy. The trick is to analyze the picture and look for colors in the scene that should be a neutral, nonspecular, textural highlight. You should try to select a neutral light gray, because if you select a white that is too bright, there may be some clipping in one or more of the color channels, and this can result in a false white balance measurement and adjustment.
Figure 6.27 Among other things, the X-Rite Gretag Macbeth ColorChecker chart is useful for taking white balance readings under the same lighting conditions as those you are about to shoot with. To take a white balance reading in Lightroom, click on the light gray patch next to the white patch.
Figure 6.28 The white balance can be measured manually by selecting the White Balance tool () and clicking a color in the image that should be near white in color. This image shows two possible white balances: one measured for the indoor lighting (left) and one measured for the outside daylight (right).