Darken the background while brightening the subject — without masking both. Duplicate & Invert creates a pixel-perfect complement of any mask in a single step.
✂️Duplicate & Invert is the fastest way to split an image into two independently editable regions.
Core Concept
What Duplicate & Invert Does
Original Mask
White = subject masked. Black = background excluded.
Duplicate & Inverted
White and black are swapped. Background is now masked.
💡Every pixel value flips: white → black, black → white. Feathered edges are preserved exactly — just mirrored.
How To
How to Duplicate & Invert
Open the Masks panel (Shift+W), right-click a mask, and choose the option from the context menu.
1
Open the Masks panel — Shift+W
You need at least one existing mask in the list to duplicate.
2
Right-click the mask row or thumbnail
A context menu appears. Look for "Duplicate & Invert" — not plain "Invert."
3
Click "Duplicate & Invert"
A new mask appears in the list, named "Copy (Inverted)." The original mask is unchanged.
4
Click the new mask to select it — apply your adjustments
The sliders below now control the inverted region. Adjust independently of the original.
The Result
Two Masks — 100% Coverage
After Duplicate & Invert, the mask list shows both masks. Together they cover every pixel in the image.
Masks Panel
Mask 1 — Subject
Exposure +0.5 applied
Adjusted ✓
Mask 1 Copy (Inverted)
Background — ready to adjust
New
Total Coverage
Mask 1
Mask 1 Inverted
No pixel covered twice. No pixel missed. Together = 100%.
Key Distinction
Duplicate & Invert vs. Plain Invert
🔁
Duplicate & Invert
Creates a new mask. Original is preserved. You end up with two masks: the original and its complement. Use when you want to edit both regions independently.
🔄
Plain Invert
Flips the existing mask in place. No copy is made. The original selection is replaced by its inverse. Use when you selected the wrong region and just want to flip it.
⚠️One mask in + Invert = one mask out (flipped). One mask in + Duplicate & Invert = two masks out. Choose accordingly.
Practical Use
Portrait Workflow
1
Masks panel → Add Mask → Select Subject
AI detects the person. The subject is now Mask 1. Adjust: Exposure +0.5, Clarity +10, Whites +15.
2
Right-click Mask 1 → Duplicate & Invert
The background mask appears instantly — every pixel not covered by the subject mask.
3
Click the inverted mask — adjust the background
Try: Exposure –0.7, Highlights –30, Saturation –15. The subject pops. Toggle \ (backslash) to compare before/after.
👤One AI selection + one invert = a complete subject-vs-background split edit. No second manual mask needed.
The inverted mask follows the exact horizon — no seam, no gap. Better than any linear gradient at a complex edge.
🏔️Sky mask → Duplicate & Invert = instant foreground mask that follows every contour of the horizon. Seam-free, always.
Editing Both Regions
Click Each Mask to Switch
The sliders below the mask list update instantly to reflect whichever mask is selected. Your adjustments only affect the active mask.
A
Click Mask 1 → adjust Region A (subject / sky)
Sliders show that mask's current values. Changes apply only here.
B
Click Mask 1 Copy (Inverted) → adjust Region B
Sliders switch to the inverted mask's values. These are completely independent of Mask 1.
O
Press O to toggle the mask overlay
See exactly which region each mask covers. Shift+O cycles overlay colors. Verify you're editing the right region before adjusting.
🖱️Neither mask affects the other. Go back and forth between them as many times as you need — each holds its own adjustments independently.
The Guarantee
100% Coverage — No Seams
Duplicate & Invert produces a mathematically perfect complement. Original + inverted = every pixel, exactly once.
Original pixel value
200
+
Inverted pixel value
55
200 + 55 = 255 · Always, for every pixel.
✅Two separately created masks may gap or overlap at complex edges. Duplicate & Invert cannot — the pixel math guarantees a perfect seam-free split every time.
Decision Guide
When NOT to Use It
✅
Use It When…
✅ One subject vs. one background
✅ Sky vs. foreground
✅ "Everything but this object"
✅ Simple two-region split
⚠️
Think Twice When…
⚠️ The inverse mixes unlike regions
⚠️ You need 3+ distinct zones
⚠️ The "everything else" is too varied
⚠️ Group photos with multiple subjects
🧩Before duplicating, ask: "What would the inverse look like?" If it's one coherent region, proceed. If it's a jumble of unlike areas, build separate masks instead.
Advanced Technique
Combining with Subtract
After Duplicate & Invert, you can further refine the inverted mask by subtracting from it — carving out exceptions.
1
Subject mask on Person A → Duplicate & Invert
The inverted mask covers everything except Person A — including Person B in the background.
2
With the inverted mask active → Subtract → Select Object
Paint Person B. They are now excluded from the background mask — no background adjustments apply to them.
3
Add a third mask — Select Object → Person B
Three non-overlapping masks: Person A, Background, Person B. Each independently adjustable.
🔧Duplicate & Invert gives you the starting point. Subtract refines it. Together they unlock complex multi-region edits from a single AI selection.
Your Homework
🎯
Duplicate & Invert Challenge
Do the split-edit workflow on a portrait and a landscape before Lesson 29.
👤 Open a portrait → Select Subject → Duplicate & Invert
☁️ Open a landscape → Select Sky → Duplicate & Invert
🏔️ Apply different treatments to sky and foreground
🔍 Check the horizon — notice there's no seam
💬 Share a before/after in the club gallery or comments
Up Next
3 Things to Remember
1
Right-click → Duplicate & Invert
Original is untouched. New mask is pixel-perfect complement. Two independent edits, two regions.
2
Zero Seams, Guaranteed
Original + inverted = 100% of pixels, exactly once. Better alignment than two separately created masks at any edge.
3
Best For Two-Region Splits
Subject vs. background. Sky vs. foreground. One AI selection + one invert = complete split edit.
Lesson 29 — Lightroom Classic
Other Mask Options
Renaming masks, reordering them, toggling visibility, using mask groups, and all the remaining mask management tools in the panel. Everything you need to stay organized on complex multi-mask edits.