Screen Replacement with Fake Reflections
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How to Fake Realistic Reflections for Screen Replacements in DaVinci Resolve
Screen replacements are a common task for video editors and compositors, but taking an ordinary screen insert and giving it life requires attention to detail. The biggest giveaway of a fake screen is the lack of reflections. Because screens are often filmed while turned on, the "free" natural reflections are lost in the light of the practical screen content.
In this guide, we will walk through a workflow in DaVinci Resolve Fusion to insert a screen and add fake reflections using inverted tracking data for a realistic result.
The Workflow: Linear Color Space
Before diving into the composite, it is crucial to ensure the lighting math works correctly. This tutorial uses an ACES CG workflow, meaning the footage is linearized.
The Plate: The main footage (Nintendo Switch) is already in ACES CG.
The Insert: The graphic we are inserting (Tetris Effect) is standard sRGB/Rec.709.
** The Fix:** To make the light levels work properly, add an ACES Transform node after the graphic. Set the input to "sRGB texture" and output to "ACES CG". This ensures the sRGB texture is linearized so the light is properly placed onto the screen.
Step 1: Tracking the Device
We need to track the handheld device to pin our new screen to it.
Planar Tracker: Add a Planar Tracker node to your main plate.
Reference Frame: Go to frame 0 and set it as your reference frame by clicking "Set".
Selection: Draw a shape around the screen, selecting areas with contrast but trying to avoid existing reflections if possible.
Settings: Set the Tracker Type to Hybrid Point/Area and Motion Type to Perspective (essential for handheld devices). Track forward.
Verify: To check the track, switch the Operation Mode to Steady and play the clip. If the screen remains locked in place without jittering, the track is good.
Step 2: Inserting the Screen
Once the track is solid, we can insert the new graphic.
Export Transform: In the Planar Tracker, switch back to "Track" mode and click Create Planar Transform. This node contains all the movement data.
Corner Pinning: Add a Corner Positioner node to your linearized graphic. On your reference frame (frame 0), drag the corners of the insert to match the corners of the device screen.
Composite: Connect the Corner Positioner to the Planar Transform, and merge it over the original footage.
Note: The Planar Transform node now includes a "Scale to Source" checkbox, which simplifies resolution matching.
Step 3: Designing the Fake Reflection
To sell the effect, we need to build a reflection map that looks like light hitting the glass.
Texture: Create a Background node with a "Four Color Gradient" rather than a solid color. Use mid-grays to "paint with light".
Irregularity: Add a Fast Noise node and merge it onto the gradient using a "Multiply" blend mode. This breaks up the gradient, making it look like smoke or clouds, adding organic variance to the light.
Highlights: Use a Paint node to draw specific white "light swipes" or highlights across the frame. Ensure the "stroke" icon is selected so the paint stroke appears on the entire clip.
Step 4: Inverted Motion for the Reflection
Reflections on a moving screen should not move perfectly in sync with the handheld moving screen; they should move in the opposite direction.
To achieve this without complex 3D perspective:
Reuse the Tracker: Copy your original Planar Tracker node.
Steady Mode: Set this copy to Steady mode, referenced from frame 0.
Apply to Reflection: Run your reflection texture (Gradient + Noise + Paint) through this Steady-mode tracker.
This causes the reflection texture to remain "locked off" relative to the frame while the screen moves, effectively creating inverted movement that mimics a reflection.
Step 5: Blending and Masking
Finally, merge the reflection over the screen insert.
Add Mode: In the Merge node, lower the Alpha Gain to 0. This acts as an "Add" operation, adding the pixels as light rather than screening them.
Masking: We only want reflections on the screen itself. Take the alpha output from the original Planar Transform (or Tracker) and plug it into the Mask input (blue input) of the reflection's Merge node.
Opacity: Adjust the Blend slider on the Merge node to control the intensity of the reflection.
Final Polish
To make the composite completely seamless, add these finishing touches:
Tilt Shift Blur: Add a Tilt Shift Blur effect to the screen insert to match the defocus of the original footage. This creates a realistic depth of field.
Motion Blur: Enable motion blur inside the Planar Transform settings. Increasing the quality to around 10 samples usually yields good results.
Grain: In the Color page, use the Film Look Creator or grain tools to add a layer of grain over the entire image. This ties the digital insert and the organic footage together.
