Intersect keeps only the pixels that exist in both masks simultaneously. It's the most surgical tool in the Lightroom masking system — combining two independent selection criteria into a single, pinpoint zone.
🔬Intersect is the tool when a brush alone can't get you there — it selects by two dimensions at once: location AND brightness, content AND hue.
Core Concept
The Venn Diagram Overlap Only
Mask A
Everything in A
Mask B
Everything in B
A ∩ B
Only where BOTH agree — final mask
💡A pixel must qualify for Mask A AND Mask B to survive the intersection. If it's only in one — it's excluded.
How To
How to Intersect
Build your first mask, then use the three-dot menu to add an Intersect component.
1
Create Mask 1 — any tool (Subject, Sky, Brush, Gradient…)
This is your base mask (Mask A). Cover the broad area you want to start from.
2
Click the three-dot (…) menu next to the mask name
You'll see Add, Subtract, and Intersect options — each with a submenu of mask tools.
3
Click Intersect → choose your second mask tool
Lightroom instantly restricts the mask to the overlap. Both components remain independently editable in the panel.
✅The mask overlay updates immediately — you'll see the coverage collapse to only the intersection zone. Toggle the overlay (O key) to compare.
Comparison
Add vs. Subtract vs. Intersect
➕ Add
Everything in either — area grows
➖ Subtract
A minus B — area shrinks
∩ Intersect
Only overlap — most targeted
🎯Add = more area · Subtract = less area · Intersect = more specific area. Choose based on whether you need to grow, shrink, or narrow your selection.
Use Case #1
Select Subject ∩ Luminance Range
Target only the bright highlights on the subject — AI edges, no brushing required.
1
Create Mask — Select Subject
AI selects the entire subject. Whole person protected — face, hair, clothing, shadow side.
2
Three-dot → Intersect → Luminance Range
Sample a bright highlight (forehead, cheekbone). Set range to ~65–100. Add smooth falloff at the lower edge.
Only the lit areas brighten and smooth. Shadow side, dark hair, background — untouched.
✨The result: dimensionally sculpted light — bright side lifts, shadow side stays. A three-click technique that used to take minutes of careful brushwork.
Use Case #2
Brush ∩ Color Range
Target only the red tones within a brushed geographic zone — other colors in that area stay untouched.
🖌️
Step 1 — Brush
Paint roughly over the area of interest. Precision doesn't matter yet — just define the geographic zone.
🎨
Step 2 — Intersect Color Range
Sample the target hue. The mask collapses to only that color within your brush zone. Green foliage right next to red flowers? Not included.
🌹Two independent criteria: geographic location (brush) AND hue (color range). The overlap is precise in both dimensions simultaneously.
Use Case #3
Select Subject ∩ Linear Gradient
Restrict a full-subject mask to only the upper half — without touching lower body or background.
1
Select Subject — full person selected
Too broad. You only want face and upper body — not legs or lower clothing.
2
Intersect → Linear Gradient from top down to waist
The gradient's full-strength zone covers the upper half of the frame. Lower body falls outside — vanishes from the mask.
3
Result — upper subject only
Add brightness. The lower body and background in the upper frame are completely unaffected.
🧍Reverse the gradient direction for a lower-body-only mask. Same technique, inverted geometry.
Use Case #4
Select Sky ∩ Radial Gradient
Find only the area that is BOTH in the sky AND inside a radial gradient centered on the sun.
🌤️
Select Sky alone
Entire sky protected — boosts the whole sky evenly. You want only the sun's glow zone.
⭕
Radial Gradient alone
Circular zone around the sun — but it would bleed into the foreground below the horizon too.
Sky ∩ Radial = circular glow zone, clipped to the sky boundary — foreground excluded automatically
☀️Set the Radial Gradient feather to 60–70% so the glow blends naturally. Invert the radial so the inside of the circle is protected.
Why It Matters
Brush vs. Intersect
🖌️
Brush Alone
❌ Can't distinguish bright from dark
❌ Can't distinguish red from green
❌ Follows your hand — not image content
❌ Hard edges need constant zooming
∩
Intersect
✅ Location AND luminance AND color
✅ AI subject/sky edges — no painting
✅ Feathering built into range tools
✅ Fully re-editable, non-destructive
🧠Each mask tool selects along one dimension. Intersect combines two dimensions simultaneously — a selection that no single tool and no brush can replicate.
UI Reference
Reading the Component List
The Mask panel shows intersect components indented under the base mask, marked with a ∩ symbol.
Mask Panel — Component View
🎭
Mask 1 — Select Subject
BASE
∩
Luminance Range (bright tones)
∩
✏️Click any component to re-open its controls. Adjust the Luminance Range, reposition a gradient, change a Color Range sample — the mask updates live.
Practical Workflow
Portrait — Highlight Sculpting
Select Subject ∩ Luminance Range — lift only the highlights on skin. Try it right now.
Open a portrait in Develop. Open the Masking panel.
Create New Mask → Select Subject. Confirm the AI edge on the subject.
Three-dot menu → Intersect → Luminance Range.
Sample a highlight on the forehead or cheekbone. Set range ~65–100. Add smooth falloff.
Press O to toggle the mask overlay — confirm shadow side is NOT included.
Press \ to compare before and after. Notice the sculpted light on the subject.
Your Challenge
☀️
Intersect Challenge
Find a landscape with sky and a visible sun or bright horizon. Build this mask.
🌤️ Create Mask → Select Sky. Confirm the AI horizon edge.
⭕ Three-dot → Intersect → Radial Gradient. Center on the sun.
🌡️ Set feather to 60–70%. Check Invert so the inside is protected.
☀️ Boost Exposure +0.4, Highlights +20, Temperature +15.
✅ Confirm foreground is NOT affected — only the sky glow zone.
💬 Share your before/after in the club gallery.
Lesson Recap
3 Things to Remember
1
Intersect = AND
Only pixels in both masks survive. Stricter than Add. The most targeted operation in the masking system.
2
Three-Dot → Intersect
Open the three-dot menu on any existing mask. Choose Intersect → pick a second tool. Components stay editable forever.
3
Two Dimensions at Once
Subject + Luminance. Sky + Radial. Brush + Color. Each pair selects by two independent criteria — no single tool can do that.
Lesson 27 — Lightroom Classic
Duplicating Masks
Why build complex masks from scratch every time? Lesson 27 covers copying masks within an image and across photos — batch consistency and fast iteration on sophisticated masking setups.