How to Choose the Right Mask Size for Video Inpainting
Mask size controls how much of the original frame is discarded and reconstructed. A tight mask preserves evidence, while a complete mask prevents letters, halos, or translucent edges from surviving the pass.
There is no universal pixel padding. The correct margin depends on resolution, compression, motion blur, opacity, edge softness, and how the element changes over time.
Start with the true visual footprint
Zoom in on both light and dark backgrounds. Include anti-aliased pixels, drop shadows, outline strokes, glow, and semi-transparent plates. The obvious solid center is often smaller than the contaminated area.
For moving or scaling elements, map stable time ranges. A mask sized for every possible position at once can become much larger than the element in any single frame.
Recognize masks that are too small or too large
A small mask leaves letter fragments, dark outlines, shimmer, or a ghost edge. A large mask bends lines, softens faces, repeats texture, and creates a visible patch where clean information was removed.
Adjust one variable at a time. Expand only the failing edge or split the time range before increasing the entire region.
Test at delivery conditions
Review at the final aspect ratio and resolution, not only in a scaled preview. Compression can hide a flaw in one player and reveal it after another export.
Watch at normal speed for flicker, then pause on the most complex frame. A successful still is not enough if the patch moves or pulses during playback.
Recommended workflow
- Inspect the element on both bright and dark frames.
- Include its soft edge, shadow, glow, plate, and motion blur.
- Choose separate time ranges for position, size, or opacity changes.
- Test the most complex background with the smallest complete mask.
- Expand only where residue remains and recheck motion at final size.
Frequently asked questions
Should a mask touch the watermark edge exactly?
Usually leave enough margin to include anti-aliasing, shadow, glow, and compression bleed without covering unrelated pixels.
Why does a large mask reduce quality?
It discards more real image information and asks the model to invent a larger area across every frame.
What if the watermark moves?
Split the timeline or track the position. Avoid one oversized box that covers the entire path for the whole clip.
How do I know the mask is too small?
Look for faint letters, outlines, halos, or flicker around the original edge.