Select Subject is fast and powerful — but no AI is perfect. The Add mode lets you extend any mask with any tool, covering exactly the areas the AI missed.
➕Add a brush stroke and get the other 10%. One mask, multiple components, one unified adjustment.
Core Concept
What "Add" Means
Adding to a mask creates a union — the final mask covers every pixel that any component covers. Think of it like combining two circles on a Venn diagram: the result is the total area of both.
🤖
Component 1
Select Subject — the broad AI selection. Fast, smart, gets most of what you need.
🖌️
Component 2 (Added)
Brush stroke — painted in the precise area the AI missed. Exact coverage where you need it.
∪The final mask = Component 1 plus Component 2. Not just the overlap — the entire combined area. Your adjustment applies uniformly across all of it.
How To
How to Add to a Mask
1
Create your first mask as usual
Select Subject, Select Sky, Brush — any tool. This becomes Component 1 and appears in the Masking panel.
2
Click the mask row to expand it
Click the mask name in the panel (not the eye or trash). The component list appears along with the "Add" and "Subtract" buttons.
3
Click Add → choose your tool
A dropdown shows all masking tools — Brush, Linear Gradient, Radial Gradient, Select Subject, Select Sky, Color Range, and more. Pick the right one for the area you need.
4
Paint, drag, or auto-select — overlay updates in real time
The red overlay expands to include the new area immediately. The new component appears in the list. Your adjustment now covers the full expanded selection.
The Component List
What You See in the Panel
Every addition appears as a sub-item under the parent mask. Each component has its own eye icon (toggle visibility) and trash icon (delete component).
Masking Panel — Mask 1 (3 components)
Mask 1
👁 ⋯
Select Subject
👁 🗑
Brush 1 — missed shoulder
👁 🗑
Brush 2 — hair detail
👁 🗑
💡Each component is independent — toggle, delete, or add more without affecting the others. One parent mask, any number of components.
Most Common Add
Add with Brush
The classic combo: Select Subject for the broad selection, then Brush to paint in the areas the AI missed.
1
Press O to toggle the overlay — inspect for missed areas
Look at hair edges, hands, shoulders blending into the background. These are where the AI typically misses.
2
Expand mask → Add → Brush. Set Feather ~60
Feather around 60 blends the brush edges naturally with the AI selection. Use [ and ] to resize the brush as you work.
3
Paint the missed area — hold Alt/Option to erase overshoot
Alt (Win) / Option (Mac) switches the brush temporarily to Erase mode. If you paint outside the subject, hold Alt/Option and paint it back off.
⚡Alt/Option = instant erase within the brush. Paint boldly — you can always erase the overshoot without touching the underlying AI selection.
Add with Gradient
Add with Linear Gradient
When Select Sky stops too early near the horizon, a Linear Gradient addition is the most natural-looking fix — it fades right where the sky itself fades.
🌅
The Problem
Select Sky cuts off at the horizon — hazy transition zone not included. A hard brush edge looks unnatural there.
📐
The Fix
Add → Linear Gradient. Drag from clear sky downward into the missed zone. The gradient fades naturally — matching the real-world horizon transition.
✨Match your tool to the nature of what you're masking. The horizon is a gradient in real life — so use a gradient to mask it.
Unusual but Useful
Add with Select Subject
Any tool can be added to any mask. Adding Select Subject to an existing sky mask lets you apply the same adjustment to both areas at once — with one mask, one setting.
🎞️
Film Grain Effect
Want grain on both sky and subject? Select Sky + Add Select Subject. One grain adjustment covers both areas consistently.
🎨
Selective Desaturation
Desaturate sky and subject together while leaving the midground untouched. One combined mask handles both.
🔓No restrictions on what can be combined. Select Subject + Select Sky, Color Range + Brush, Gradient + Luminance Range — any combination that serves the image.
Visual Guide
What the Overlay Shows
The red overlay covers every pixel where any component is active. Any pixel not covered by at least one component is left unaffected by your adjustment.
R
Red overlay = selected and adjusted
Any area showing red in the overlay receives your develop adjustments. This is the exact coverage of the combined mask.
—
No overlay = not selected, not adjusted
Areas without red overlay are untouched. If there's a gap between two components, that gap is unmasked — your adjustment won't reach it.
O
Press O to toggle the overlay on/off
Shift+O cycles through overlay colors: red, green, white, black. Use whichever color contrasts best with your image.
👁The overlay is ground truth. If it shows red there, the adjustment applies there. Trust the overlay — always inspect it after creating or modifying a mask.
Component Control
Toggling Components On/Off
Click the eye icon next to any component to hide it from the combined mask temporarily. The overlay updates instantly — showing exactly what that component contributes.
🔍
Diagnose
Toggle each component to understand what it's covering. A component that barely changes the overlay when hidden may be redundant.
🎯
Isolate
Hide all but one component to see that component in complete isolation. Great for checking whether a brush stroke stayed inside the subject.
💡Use the eye toggle liberally — it's the fastest way to understand a multi-component mask and catch any mistakes before they affect your edit.
Surgical Removal
Deleting a Component
Click the trash icon next to any component to remove it. The parent mask and all other components remain completely intact.
1
Toggle the eye first — confirm it's the problem component
Before deleting, use the eye icon to verify this is the component causing the issue. Diagnose before acting.
2
Click the trash icon — immediate, no confirmation dialog
Lightroom removes the component instantly. The overlay updates to reflect the remaining components. Cmd/Ctrl+Z can undo if you act quickly.
3
Everything else is preserved — no need to undo or rebuild
Parent mask intact. Other components intact. Adjustment settings intact. Only that one component is gone. Use this instead of Cmd+Z whenever possible.
🗑Trash icon = surgical scalpel. Cmd+Z = sledgehammer. For component-level mistakes, always prefer the trash icon.
Practical Workflow
Portrait: Three Components, One Mask
A complete portrait masking workflow — Select Subject plus two Brush additions for the areas the AI missed.
Run Select Subject — toggle the overlay and inspect for missed areas
The final mask covers every pixel from every component. Nothing is ever removed from earlier components when you add. Only expansion.
2
Any Tool + Any Mask
Brush, Gradient, Select Subject, Color Range — any tool can be added to any mask. The only limit is what makes sense for your image.
3
Toggle + Trash
Eye icon to understand each component. Trash icon to surgically remove just the problematic one. Everything else stays intact.
🧠Add expands the mask. Next lesson: Subtract perfects it — removing specific pixels from a mask that covered too much.
Up Next
Lesson 25 — Lightroom Classic
Masking: Subtracting from Masks
You've learned to grow a mask with Add. In Lesson 25, we flip it — Subtract mode removes specific areas from an existing mask. AI selection bleeds into the background? Subtract a Color Range. Sky mask dipped into a rooftop? Subtract a brush stroke. Add expands. Subtract perfects.
Subtract ModeColor Range RemovalPrecision Refinement