macOS Preview - chunhualiao/public-docs GitHub Wiki
To remove blank (transparent or white) margins from a PNG image on macOS, you can use several methods depending on your preference:
Use Preview (Manual Crop)
- Open the PNG in Preview.
- Click and drag to select only the content area (excluding blank margins).
- From the menu, select: Tools → Crop.
- Save the file (File → Save or Export as PNG).
🔸 Limitation: Manual; not ideal for batch or pixel-precise trimming.
To edit a JPG file on macOS — like drawing a circle to highlight something — you can use the built-in Preview app. It’s quick and doesn’t require any extra software.
- Double-click the .jpg file — it will open in Preview by default.
Click the Markup toolbar button (looks like a little pen tip ✏️ or toolbox).
If you don’t see it:
- choose View > Show Markup Toolbar from the menu.
Great question! In macOS Preview (and other apps using the Markup toolbar), Sketch and Draw may look similar, but they behave a bit differently—especially depending on your device (e.g., trackpad vs. iPad with Apple Pencil).
Here’s a breakdown:
✏️ Sketch Tool (the scribbly line icon)
• Input: Freehand drawing using your mouse or trackpad.
• Smart detection: macOS tries to recognize what you’re drawing.
• If you draw a rough circle, Preview might automatically convert it into a perfect circle.
• You can choose between keeping your original shape or using the suggested one.
• Great for: Quick shapes, messy diagrams, rough highlighting with cleanup help.
🖊️ Draw Tool (the smoother pen icon)
• Input: Raw freehand drawing.
• No shape recognition – what you draw is exactly what you get.
• Only available if you’re using a Force Touch trackpad or Apple Pencil (on iPad via Sidecar or Continuity Markup).
• Supports pressure sensitivity (thicker lines when pressing harder).
• Great for: Artistic, natural handwriting or sketching with precision.
TL;DR
| Tool | Smart Shape Detection | Freehand Feel | Pressure Sensitive | Best For |
|---|---|---|---|---|
| Sketch | ✅ Yes | ✅ Yes | ❌ No | Diagrams, clean markup |
| Draw | ❌ No | ✅ Very | ✅ Yes | Natural drawing, handwriting |
Let me know which Mac you’re using—I can tailor the answer if you’re on a MacBook Air vs. using an iPad via Sidecar.