Image Adjustments, Retouching, and Color
Tonal adjustments
Know the family: Levels (input/output black and white points, gamma), Curves (point-based tonal mapping, per-channel), Brightness/Contrast, Exposure, and Shadows/Highlights. Understand that Levels and Curves are the precision tools, and that Curves can adjust individual channels for color casts.
Color adjustments
Recognize Hue/Saturation (hue, saturation, lightness, with targeted color ranges), Color Balance, Vibrance (protects already-saturated colors and skin tones), Black & White (channel mixers for grayscale conversion), and Selective Color (CMYK-style ink control, common in print work). Match Color and Replace Color appear in questions about harmonizing images.
Retouching tools
Distinguish Clone Stamp (samples a source point) from Healing Brush (samples texture and blends color/lighting), Spot Healing (no source needed), Patch (samples a region), and Content-Aware Fill/Move. Know Dodge/Burn (lighten/darken), Sponge (saturate/desaturate), Blur/Sharpen/Smudge, and Liquify for warping. Red Eye and Dust & Scratches are narrow-purpose filters.
Color management basics
Understand color spaces (sRGB for web, Adobe RGB for wider gamut, CMYK for print), profiles, and soft proofing. A common trap: converting vs assigning a profile - assigning changes interpretation without altering pixel values; converting remaps pixels.
Worked rule of thumb
For a color cast, use Curves per channel or Levels gray-point eyedropper rather than Hue/Saturation. For skin smoothing, use Healing/Spot Healing for blemishes and frequency-separation-style low-opacity blur, not heavy Gaussian blur.
Traps
Adjustment dialogs preview but only commit on OK; Smart Filters let them stay editable.