Clipping & Selection
OpenGPEX provides a unified Clip mode with five tools for cropping, shape selection, freeform selection, and AI-powered segmentation.
Entering Clip Mode
Press Space to toggle Clip mode on/off. Once in Clip mode, use Tab to cycle forward through tools (or Shift + Tab to cycle backward). Press Escape to exit Clip mode.
Clip Tools (5)
| Tool | Shortcut | Family | Description |
|---|---|---|---|
| Rect | Tab cycle | Regular (amber) | Standard rectangular clip/selection |
| Ellipse | Tab cycle | Regular (amber) | Elliptical clip (toggle Anti-Alias for smooth/pixelated) |
| Lasso | Tab cycle | Irregular (purple) | Freeform polygon selection |
| Wand | Tab cycle | Irregular (purple) | Color-based magic wand selection |
| SAM | Tab cycle | AI (cyan) | AI segmentation (click or auto) |
Rect & Ellipse (Regular Shapes)
These produce axis-aligned geometric clips:
- Drag to define the clip area
- Use Aspect Ratio Presets to lock proportions (FREE, 1:1, 4:3, 3:4, 16:9, 9:16, 2:3, 3:2)
- Anti-Alias toggle (AA button or double-tap
A): Smooth edges on Ellipse; Rect is always pixel-aligned (AA is not available for Rect)
Lasso (Freeform Polygon)
Draw irregular selection outlines:
- Click to place anchor points (polygon mode)
- Each click adds a straight edge segment
- Click the starting point (or double-click) to close the polygon
Magic Wand
Select contiguous areas of similar color:
- Click on the area you want to select
- Toggle Anti-Aliasing for smoother edges
- Adjust Feather (0–250px) in the Option Bar for soft, graduated edges on the resulting cut/stamp
Note: In v1 the Wand's color-matching tolerance is fixed (no user-adjustable control).
SAM (AI Segmentation)
AI-powered object selection using SAM 2.1. This tool is connected to the AI Tools panel — you need to download the SAM model first (one-time; can be deleted to free space).
Two operation modes:
- Interactive (canvas click): Select the SAM tool, then click on the canvas to segment the object under the cursor (point prompt)
- Auto Segment (panel button): Click the Auto Segment button in the AI Tools panel to automatically detect and segment all objects in the image
Selection Operations
Once you have an active selection (from any tool), you can perform these operations:
| Operation | Description | Shortcut |
|---|---|---|
| Peel (Cut to Layer) | Removes selected area and places it on a new layer. The source layer keeps a hole where pixels were cut — deleting the fragment automatically restores the source. | Ctrl/Cmd + Shift + J |
| Stamp (Copy to Layer) | Copies selected area to a new layer (source layer unchanged) | Ctrl/Cmd + J |
| Invert Selection | Swaps selected/unselected areas | Ctrl/Cmd + Shift + I |
| Select from Alpha | Creates selection from layer transparency | Ctrl/Cmd + Shift + A |
| Select All | Selects the entire canvas | Ctrl/Cmd + A |
| Deselect | Clears the current selection | Ctrl/Cmd + D |
| Offset | Expand (+) or contract (-) selection by N pixels | — |
| Delete Selection | Removes selected pixels | Backspace / Delete |
Note: Select All (
Ctrl/Cmd + A) and Deselect (Ctrl/Cmd + D) only work with the Rect or Ellipse tools while in Clip mode. Select All creates a full-canvas selection in the current tool's shape.
Fragment Operations
When you use Peel (Cut to Layer), the result is a fragment — a layer that is linked back to its source. OpenGPEX tracks this relationship and provides dedicated operations:
| Operation | How to Access | Description |
|---|---|---|
| Merge Back | Right-click a fragment → Merge Back | Returns the cut fragment to its source layer, perfectly restoring the original. Works recursively — if the fragment was itself cut further, all downstream pieces are collected first. |
| Union Merge | Mark multiple fragments (click the layer number) → Merge Fragments button | Combines several fragments from the same source into a single merged fragment. The merge is purely geometric (vector precision, no quality loss). |
| Auto-restore on delete | Delete a cut fragment normally | The source layer's hole is automatically filled — no manual merge needed. |
Marking Fragments for Union Merge
- Click the layer number (left of the layer name) to mark/unmark fragments
- Marked layers show a colored indicator:
- 🟢 Green: all conditions met — ready to merge
- 🟡 Amber: mergeable with minor differences (e.g. opacity mismatch — first fragment's value wins)
- 🔴 Red: cannot merge (different source images, mixed cut/copy, etc.)
- When at least two fragments are marked green or amber, click Merge Fragments in the Layers panel
Feathering
Feathering creates a soft, gradual transition at the edge of your selection:
- 0px: Hard, crisp edges
- 1-5px: Subtle softening
- 10-20px: Significant blur/blend at edges
Useful for:
- Compositing elements from different photos
- Creating vignette effects
- Blending selections seamlessly
Canvas Operations
Resize Canvas
- Enter Clip mode → Click Resize Canvas in the Option Bar
- Enter desired Width and Height in pixels
- Confirm to apply
Create Branch
When you have a clip selection:
- Create Branch: Use the Create Branch button in the Clip toolbar to split the selected area into a new creation (branch) without clipping the canvas
Smart Guides
When moving or resizing layers, Smart Guides provide visual feedback:
- Edge alignment: Highlights when edges align with other layers
- Center alignment: Shows when centers are aligned
- Distance indicators: Displays pixel distance between elements
- Snap behavior: Layers snap to aligned positions for precision
- Configurable: Exclude layer types, ignore small layers, set max targets
Toggle Smart Guides: Ctrl/Cmd + Shift + ;
Smart Guides Settings: Ctrl/Cmd + ;
Next Steps
- Common Tasks — Quick task-oriented guides
- Drawing Tools — Brush, Eraser, and Text
- Masks & Non-Destructive Editing — Advanced masking
Last updated: 2026-08-30