The Auto Color Correction options control tonal and color corrections applied by Auto Color, Auto Levels, Auto Contrast, and the Auto option in both Levels and Curves. The Auto Color Correction options let you specify shadow and highlight clipping percentages, and assign color values to shadows, midtones, and highlights.
You can apply the settings during a single use of the Levels dialog box or Curves dialog box, or you can save the settings as default values when applying Auto Levels, Auto Contrast, Auto Color, and the Auto option in Levels and Curves.