#27. Removing Color Casts
Unfortunately, you can't always count on perfect lighting when shooting your photos. And less than ideal lighting conditions usually result in an unfavorable amount of one color throughout your pictures. This unpleasant effect is known as a color cast. Thankfully, removing these color casts is something Photoshop can do in its sleep.
To remove an undesirable color cast from a photograph, choose Image > Adjustments > Auto Color. Photoshop analyzes the shadows, midtones, and highlights and then automatically adjusts the contrast and color of the image. Sure, you could do much of this yourself via the Levels or Curves commands, but Photoshop does surprisingly well on its own. However, if you feel the result could stand a little help, Photoshop obliges by offering an Auto Correction Options dialog (Figure 27). Here you can adjust the settings Photoshop uses when running any Auto Correction commands, such as Auto Color or Auto Contrast. To access these settings, click Options in the Levels dialog (Image > Adjustments > Levels).
Figure 27. The Auto Color command does a fine job of removing color casts. But if you'd like to tweak the settings, use this dialog.