DaVinci Resolve Fusion Patch Replacer

Pro Quality Object Removal with DaVinci Resolve's Patch Replacer

Object removal is a cornerstone of visual effects, but getting it right can be tricky. You've likely faced the classic issue: you clone out an unwanted object, but the patch "sticks out like a sore thumb" because the edges and textures just don't match. Fortunately, DaVinci Resolve's Fusion page has a powerful tool that solves this problem with incredible finesse: the Patch Replacer.

This tool, especially with its Blend Clone mode, is a game-changer for creating seamless object removals. We'll break down a professional workflow to remove a badge from a moving taxi, covering everything from project setup to the final composite.

I have provided the footage to download and practice along with this tutorial as part of joining the cutting club here. This is an excellent way to help support my teaching efforts.

Step 1: Set Up a VFX Linear Workflow

Before any pixels are patched, it's crucial to work in the right color space. For VFX, this means a linear workflow, which ensures your composites and color manipulations are mathematically accurate.

• Footage Type: The demonstration uses Sony S-Log3 footage.

• Log to Linear: The first step in Fusion is to convert the footage from its logarithmic state to a linear one. This is done using the Cineon Log tool, setting the Log Type to match the source footage (e.g., Sony S-Log3).

• Viewing LUT: Working in linear space looks too dark out on a standard monitor. To view it correctly, you need to enable a viewing Look-Up Table (LUT) in the Fusion viewer. Set the Gamut View LUT to match your source and output spaces (e.g., source S-Gamut3.Cine and output sRGB). This is just for viewing and doesn't bake anything into the image.

• Reverting to Log: At the very end of your node tree, just before the MediaOut node, you'll add another Cineon Log tool. This time, you'll set its mode from Lin to Log to revert the image to its original state for the color page.

Step 2: The Performance Crop Trick

High-resolution footage can slow down complex operations. To maintain real-time playback, you only need to process the pixels you're actually working on.

1. Crop In: After the first Cineon Log tool, add a Crop node. Draw a box around the area you need to clean up and the source area you'll be cloning from. This significantly reduces the processing resolution, making everything faster.

2. Un-Crop Later: This cropped image will eventually be placed back onto the full-resolution plate. Set the resolution to the full size and add negative (minus symbol) to the offsets.

Step 3: Stabilize the Shot with the Planar Tracker

To work on a moving object, it's easiest to first make it stand still. The Planar Tracker is perfect for this.

• Track the Motion: Add a Planar Tracker node after the Crop node. On your reference frame (e.g., frame zero), draw a shape around the surface of the object you want to track, like the side of the car, avoiding other moving elements like the tire. Set the Motion Type to something appropriate like Translation, Rotation, and Scale and track forward.

• Stabilize the Image: Once tracked, change the Operation Mode from Track to Steady. This locks the tracked area in place, creating a stabilized plate that's easy to paint on. You can verify the track by placing your cursor over a point; if it doesn't move during playback, you have a solid track.

Step 4: Patch Replacer with a Custom Shape

Now for the magic. While the Patch Replacer can use basic rectangles or ellipses, a custom shape gives you precise control. The setup, however, is not immediately obvious.

1. Create the Alpha Shape: Add a Matte Control node after the stabilized Planar Tracker. Use a B-Spline tool to draw a precise shape around the object you want to remove (the badge).

2. The Unpre-multiplied Trick: Feed the B-Spline's output into the foreground (green) input of the Matte Control node. In the Matte Control inspector, set Combine to Combine Alpha. Crucially, do not check Post-multiply Image. This creates an unpre-multiplied image, which is exactly what the Patch Replacer needs.

3. Apply the Patch: Add the Patch Replacer tool after the Matte Control.

   • In the inspector, set the Region Shape to Alpha Channel.

   • Set the Fill Method to Blend Clone for the best results.

   • On-screen, you can now move the source box to a clean area of the car to fill in the patch. The Blend Clone mode will seamlessly merge the textures and lighting.

Step 5: Putting It All Back Together

You have a clean, stabilized patch. Now it's time to reintroduce motion and composite it back into the full-frame shot.

1. Multiply the Patch: After the Patch Replacer, add an Alpha Multiply node. This cuts out the patch according to its alpha channel, preparing it for compositing.

2. Re-apply Motion: Add a second Planar Tracker node (you can copy the first one). On this one, simply check the box for Invert Steady. This will re-apply the original motion to your patch, making it move with the car again.

3. Un-Crop the Patch: Now, reverse the performance crop from Step 2. Add a copy of your original Crop node and manually enter the full resolution (e.g., 3840x2160). Then, place negative values in front of the X and Y offsets to position the patch correctly in the full-size canvas.

4. Final Merge: Use a Merge node to place your final, moving patch over the original, full-frame footage.

Step 6: Stencil Alpha

Sometimes a patch covers up fine details you want to keep, like the thin line on the car door. You can easily restore this.

• While the patch is still stabilized (before the "Invert Steady" tracker), insert a Merge node.

• Use a Polygon tool to draw an open line that matches the original detail. Increase its Border Width to give it thickness.

• Feed this polygon into the foreground of the new Merge node and set the merge's Operator to Stencil. This will cut the line out of your patch, allowing the original pixels from the background to show through.

And that's it! You have a workflow that not only produces a professional, seamless object removal but is also optimized for high-performance playback, even on modest hardware. By understanding how to properly work in a linear space and leveraging the unique power of the Patch Replacer's Blend Clone and custom alpha modes, you can tackle even the most challenging removal shots.