Source: https://github.com/aipoch/medical-research-skills

When to Use

• You need to convert an ID photo background to a required solid color (blue/white/red) for official submissions.
• You need to add a visible “for application only” style watermark to prevent misuse of shared ID photos.
• You need to batch-generate multiple variants while keeping the original image unchanged (explicit output path).
• You need an offline, local-only tool (no network access) for processing sensitive personal images.

Key Features

• Background color replacement for ID photos:
  • Supported target colors: blue, white, red
  • Detects the dominant background color using edge pixels and replaces it using color-distance matching
• Text watermark overlay:
  • Supported positions: top-left, top-right, bottom-left, bottom-right, center
  • Configurable opacity, font size, and font color
• Input/output constraints:
  • Supports JPG and PNG only
  • Output keeps the same format as the input
  • Does not overwrite the original file (output path must be provided)
• Local processing only:
  • Reads only from user-provided input paths and writes only to user-provided output paths

Dependencies

• Python 3.x
• pillow (PIL) — version not pinned
• numpy — version not pinned

Install:

python -m pip install pillow numpy

Example Usage

Background color replacement (JPG):

python scripts/id_photo_tool.py change-bg \
  --input input.jpg \
  --output output.jpg \
  --color blue

Background color replacement (PNG):

python scripts/id_photo_tool.py change-bg \
  --input input.png \
  --output output.png \
  --color white

Add a text watermark:

python scripts/id_photo_tool.py add-watermark \
  --input input.jpg \
  --output watermarked.jpg \
  --text "For application use only"

Implementation Details

Background Color Replacement

• Background sampling: The tool estimates the original background color by sampling pixels along the image edges (where background is most likely present).
• Color-distance based replacement: Pixels close to the estimated background color (by color distance) are treated as background and replaced with the selected target color.
• Supported target colors:
  • blue
  • white
  • red

Text Watermark

• Placement: One of five positions is supported: top-left, top-right, bottom-left, bottom-right, center.
• Rendering parameters:
  • Opacity controls watermark transparency.
  • Font size controls text scale.
  • Font color controls text color.
• Output behavior: The watermark is composited onto the image and saved to the specified output path without modifying the original input file.

Security / Compliance Notes

• No network access is used; all processing is performed locally.
• The script only accesses file paths explicitly provided via CLI arguments.
• The tool requires an explicit output path and does not overwrite the original file by default.