Skill: wxttt/remove-watermark (version 0.1.0)

--- name: remove-watermark description: Remove light-colored text watermarks from white-background document images (exam papers, scanned documents). No API key needed - pure local image processing. Use when the user wants to remove watermarks, clean up document screenshots, or remove light text overlays from images. --- # Remove Watermark Remove watermarks from white-background document images. Pure local processing, no API key needed. ## When to Use Trigger this skill when the user wants to: - Remove watermarks from document images or screenshots - Clean up exam paper screenshots for printing - Remove light text overlays (e.g., "公众号·xxx", website names) ## Workflow: 4-Step Process The script path is `scripts/remove_watermark.py` relative to this SKILL.md. Use `uv run --with Pillow --with numpy` (add `--with scipy` only when using `--region full`). ### Step 1: Visual Analysis (Claude reads the image) Use the Read tool to look at a sample image. Identify: - **Is there a watermark?** If no, skip processing. - **Where is it?** (bottom-right corner, center, scattered across the image) - **What type?** (light gray text, dark logo/stamp, colored) - **Does it overlap with content text?** Estimate the watermark region as approximate percentages: y0%, y1%, x0%, x1%. ### Step 2: Brightness Analysis (script analyzes the region) Run the `analyze` subcommand on the watermark region to determine the right threshold: ```bash uv run --with Pillow --with numpy python3 <skill-path>/scripts/remove_watermark.py analyze <image> --region "y0,y1,x0,x1" ``` Example: `analyze sample.jpg --region "94,100,60,100"` This prints brightness distribution and a **suggested threshold**. ### Step 3: Remove Watermark Use the suggested threshold and region from Steps 1-2: ```bash # Region mode (preferred - zero damage to text outside the region) uv run --with Pillow --with numpy python3 <skill-path>/scripts/remove_watermark.py remove <input> -o <output> --region "y0,y1,x0,x1" --threshold <N> # Full mode (when watermark is scattered everywhere - needs scipy) uv run --with Pillow --with numpy --with scipy python3 <skill-path>/scripts/remove_watermark.py remove <input> -o <output> --threshold <N> ``` **Region presets:** `bottom-right`, `bottom-left`, `top-right`, `top-left`, `bottom`, `top`, `right`, `left`, `center`, `full` **Custom region:** `--region "y0,y1,x0,x1"` as percentages (e.g., `"94,100,60,100"` = bottom 6%, right 40%) ### Step 4: Verify and Auto-Retry Use the Read tool to check the output image. You MUST verify and retry if needed — do not stop after one attempt. **Check these two things:** 1. Is the watermark gone? 2. Is the text content intact (not lightened or damaged)? **If watermark is still visible**, retry with adjusted parameters: | Problem | Fix | |---------|-----| | Watermark still visible | Lower the threshold (e.g., 180 → 130 → 80) | | Only partially removed | Expand the region (e.g., widen by 5-10% in each direction) | | Text got damaged/lightened | Raise the threshold or shrink the region to avoid text areas | | Wrong area processed | Re-examine the image and correct the region coordinates | **Retry rules:** - Retry up to 3 times with different parameters before giving up - Each retry: adjust ONE parameter at a time (threshold OR region, not both) - If the suggested threshold from `analyze` didn't work, try halving it - If threshold=50 still doesn't remove the watermark, try threshold=1 with a tighter region (the region likely has no real content, so blanking it entirely is safe) - After 3 failed attempts, report to the user what was tried and ask for guidance ## Command Reference ### analyze ``` remove_watermark.py analyze <image> [--region REGION] ``` Prints brightness distribution and suggested threshold for a region. ### remove ``` remove_watermark.py remove <input...> [-o OUTPUT] [--region REGION] [--threshold N] [--enhance] ``` | Flag | Default | Description | |------|---------|-------------| | `--region` | `full` | Region to process (preset name or `y0,y1,x0,x1`) | | `--threshold` | `180` | Brightness cutoff for watermark pixels | | `--enhance` | off | Boost text contrast after removal | | `--preview` | off | Print stats without saving | ## Tips - **Region mode is always preferred** over full mode when watermark is localized. It leaves all text perfectly intact. - For dark watermarks (logo, stamps), use a **low threshold** (80-120) with a **tight region**. - For light gray text watermarks, use a **higher threshold** (160-200). - **Same batch**: if all images in a folder have the same watermark position, analyze one image and apply the same settings to all. - Combine with **image-to-pdf** skill: remove watermarks first, then combine into PDF.


Security scan verdicts — ClawScan: clean | static analysis: clean | VirusTotal: clean | SkillSpector: clean (LOW)