Transparent Gif Loop

Transparent Gif Loop

<SKILL_DIR> = the folder containing this SKILL.md.

Quick Start

• Install Pillow if needed: python -m pip install Pillow
• Create a transparent animated WebP: python <SKILL_DIR>/scripts/process_gif.py animated input.gif output.webp --size 220 --threshold 10
• Extract a transparent still: python <SKILL_DIR>/scripts/process_gif.py still input.gif output.webp --still-frame 0 --size 275 --threshold 10

File Safety

• Treat input GIFs and generated frame data as untrusted media. Process only expected GIF/WebP/image files, not archives or executable content.
• Write to a separate output path by default. Do not overwrite the input file unless the user explicitly asks.
• Stop and ask before processing unusually large dimensions, very high frame counts, or files that could exhaust memory/disk.
• Strip or avoid carrying metadata into public outputs unless the user explicitly needs metadata preservation.

Workflow

1. Run animated mode with the defaults first.
2. If the loop seam still snaps, increase --bridge-frames and --bridge-duration.
3. If the source has dead frames or repeated poses, trim to a cleaner cycle with --loop-start and --loop-end.
4. If the seam is still ugly after tuning, treat it as a source-asset problem instead of overfitting the bridge. Ask for a better export or fall back to a still cutout.

Script

• Use <SKILL_DIR>/scripts/process_gif.py for both animated and still outputs.
• After script edits, run python scripts/smoke_test.py from this skill folder to verify still and animated WebP generation on a tiny local fixture.
• The script:
  • Removes near-black matte pixels with an alpha threshold
  • Resizes frames for web delivery
  • Retimes playback with --speed-scale
  • Inserts interpolated midpoint frames between adjacent frames
  • Adds an eased last-to-first bridge
  • Optionally trims to an internal frame range

Helpful Flags

• --threshold: Lower values preserve more dark detail.
• --size: Maximum output dimension in pixels.
• --speed-scale: Values greater than 1 slow playback; values less than 1 speed it up.
• --midpoint-frames: Number of interpolated frames between every adjacent pair.
• --bridge-frames: Extra eased frames added only at the loop seam.
• --bridge-duration: Duration in milliseconds for each seam frame.
• --loop-start / --loop-end: Inclusive frame range for trimming to a cleaner loop.
• --still-frame: Frame index to use in still mode.

Notes

• Animated WebP is usually a better web target than GIF after cleanup.
• This workflow can hide bad seams, but it cannot create a mathematically perfect loop from source frames that never return to the same pose.