Why shoot raw?
Table of Contents
White balance control
Adjusting the white balance on a raw file is fundamentally different from attempting to do so on an already-rendered image in Adobe Photoshop®.
As Figure 1 shows, Photoshop edits are inherently destructive—you wind up with fewer levels than you started out with. But when you change the white balance as part of the raw conversion process, the edit is much less destructive, because instead of changing pixel values by applying curves, you’re gently scaling one or two channels to match the third. There may be very few free lunches in this world, but white balance control in Camera Raw is a great deal cheaper, in terms of losing data, than anything you can do to the processed image in Photoshop.
Figure 1: Destructive editing
Figure 2: Before-and-after histograms show the loss of levels. The top histogram shows the state of the unedited image; the bottom one shows the state of the image after editing. The gaps indicate lost levels where the tonal range was stretched, and the spikes indicate lost differences where the tonal range was compressed.
