GIMP is a powerful free image editor, but its interface can feel unfamiliar if you’re coming from Photoshop. This guide covers the essentials.

Installation

brew install --cask gimp

The Interface

When you first open GIMP, you’ll see three floating windows. You can switch to single-window mode via Windows → Single-Window Mode. Do this — it makes the experience much more familiar.

Essential Tools

  • Crop (Shift+C) — Trim your image
  • Scale (Shift+S) — Resize an image or layer
  • Move (M) — Move layers around
  • Text (T) — Add text
  • Heal (H) — Remove blemishes by sampling nearby areas

Working with Layers

Layers work exactly like Photoshop. Each layer can have its own opacity, blend mode, and visibility. Use Ctrl+Shift+N to create a new layer.

Most edits should happen on new layers so you can always go back.

Common Tasks

Resize an image: Image → Scale Image → Enter new dimensions → Scale

Remove a background: Use the Fuzzy Select tool (U), click the background, press Delete. For complex edges, use the Paths tool (B) to draw a selection.

Adjust colors: Colors → Levels (or Curves). Drag the sliders to adjust shadows, midtones, and highlights.

Export for web: File → Export As → Choose JPEG or PNG. GIMP’s native format is XCF (like PSD) — use Export, not Save, for sharing.

Key Shortcuts

ShortcutAction
Ctrl+ZUndo
Ctrl+Shift+ZRedo
[ / ]Smaller / larger brush
Ctrl+Shift+NNew layer
Ctrl+LLayers panel