Gemini Sparkle Remover

Gemini sparkle remover

Use this when a user needs to remove a visible Gemini sparkle/corner mark from an image while preserving the original and producing clear before/after proof.

This skill uses allenk/GeminiWatermarkTool by default. It edits visible pixels only; it does not edit metadata or invisible watermarking.

What this does

• Keeps the source image unchanged.
• Installs or locates allenk/GeminiWatermarkTool.
• Runs GeminiWatermarkTool on the source image.
• Creates a derivative image with the visible sparkle removed when the tool detects it.
• Produces a review sheet with full-image and bottom-right crop before/after proof.
• Reports the tool output, diff metrics, and whether removal was attempted.

Setup

The remover comes from:

https://github.com/allenk/GeminiWatermarkTool

For a fresh agent/environment, run setup from this skill directory and install the latest release binary:

TOOL_DIR="$PWD/.tools/GeminiWatermarkTool-src"
git clone https://github.com/allenk/GeminiWatermarkTool.git "$TOOL_DIR"
cd "$TOOL_DIR"

python3 - <<'PY'
import json
import platform
import urllib.request
from pathlib import Path

repo = 'allenk/GeminiWatermarkTool'
release = json.load(urllib.request.urlopen(f'https://api.github.com/repos/{repo}/releases/latest', timeout=30))
tag = release['tag_name']
assets = {asset['name']: asset['browser_download_url'] for asset in release['assets']}

system = platform.system().lower()
if system == 'linux':
    asset = 'GeminiWatermarkTool-Linux-x64.zip'
elif system == 'darwin':
    asset = 'GeminiWatermarkTool-macOS-Universal.zip'
elif system == 'windows':
    asset = 'GeminiWatermarkTool-Windows-x64.zip'
else:
    raise SystemExit(f'unsupported platform: {platform.system()}')

for name in [asset, 'SHA256SUMS.txt']:
    url = assets[name]
    print(f'downloading {name} from {tag}')
    urllib.request.urlretrieve(url, name)
PY

sha256sum -c SHA256SUMS.txt --ignore-missing
python3 - <<'PY'
import zipfile
from pathlib import Path
zip_path = next(Path('.').glob('GeminiWatermarkTool-*.zip'))
with zipfile.ZipFile(zip_path) as z:
    z.extractall('dist')
PY
chmod +x ./dist/GeminiWatermarkTool
./dist/GeminiWatermarkTool --version
cd - >/dev/null

Then either pass the binary explicitly:

python3 templates/sparkle_remover.py \
  --tool ./.tools/GeminiWatermarkTool-src/dist/GeminiWatermarkTool \
  --input ./samples/source.png \
  --output ./samples/derivative.png \
  --review ./samples/review.jpg

or export it once for the session:

export ALLENK_GEMINI_WATERMARK_TOOL="$PWD/.tools/GeminiWatermarkTool-src/dist/GeminiWatermarkTool"

Install Python dependencies for the wrapper/review sheet:

python3 -m pip install Pillow

Recommended workflow

1. Copy the source image and keep the original unchanged.
2. Make sure GeminiWatermarkTool is installed and available via --tool, ALLENK_GEMINI_WATERMARK_TOOL, or PATH.
3. Run the remover script and create a derivative plus review sheet.
4. Inspect the review sheet at high zoom:
   • the sparkle should be gone or visibly reduced
   • the local texture should not smear badly
   • there should be no dark inverse sparkle, blur blob, or obvious rectangular patch
   • nothing outside the expected watermark region should change
5. If the result is bad, leave the original unchanged and investigate the real watermark geometry instead of guessing with broad pixel edits.

Command pattern

Run on an image:

python3 templates/sparkle_remover.py \
  --tool ./.tools/GeminiWatermarkTool-src/dist/GeminiWatermarkTool \
  --input ./samples/source.png \
  --output ./samples/derivative.png \
  --review ./samples/review.jpg

Create a synthetic test image to verify wrapper/review-sheet wiring only. This does not prove remover quality, because the synthetic sparkle is not a real Gemini watermark profile:

python3 templates/sparkle_remover.py \
  --tool ./.tools/GeminiWatermarkTool-src/dist/GeminiWatermarkTool \
  --make-sample ./samples/source.png \
  --output ./samples/derivative.png \
  --review ./samples/review.jpg \
  --no-remove

Useful flags:

--tool /path/to/GeminiWatermarkTool  # override remover binary
--no-remove                          # copy image and make proof only

Verification checklist

Before reporting success, verify:

• The original file still exists and was not overwritten.
• The derivative output exists.
• Source and derivative dimensions match.
• The review sheet exists.
• The sparkle is gone or visibly reduced in the bottom-right crop.
• No obvious blur blob, dark inverse sparkle, rectangular patch, or off-target edit was introduced.
• The JSON report says method: allenk/GeminiWatermarkTool and scope: visible_pixel_sparkle_removal.

See references/verification-checklist.md for a compact review checklist.