A More Precise Curves

This quick tip is essential for retouching and color correction

The Curves dialog box (Cmd-M or Ctrl-M) is considered by many experts to be the best place to manipulate colors and values for color-correction purposes. The Levels dialog box takes second place in that race, but Levels is really just Curves with only three editable points—shadow, highlight and 50% midtone. Levels’ only advantage is its histogram, but since CS Photoshop has had its own Histogram palette so Levels is no longer necessary for reading histograms. But the fact remains that Curves is the place to go for precision and ease of use when manipulating color and value.

The problem with the standard Curves dialog box (Fig. 1) is that it is imprecise. The default grid only marks 25, 50 and 75 percent, so if you’re wanting to pinpoint 30% or 40% you’ll have to guess. But there’s a hidden trick: Option-click the grid space and it will be demarcated in tenths instead of quarters.

Figure 2 is the new Curves dialog box, marked in tenths, and it makes it a lot easier to manipulate precise values.

Figure 1: The default Curves dialog box.

Figure 2: The Curves dialog box with the grid space demarcated in tenths.