fdwm 0.2.1

Frequency-domain watermarking library and CLI

FDWM - Frequency Domain Watermarking

A Python library for embedding and extracting watermarks in images using frequency domain techniques. Supports both image and text watermarks with a command-line interface.

Features

• Frequency Domain Watermarking: Uses FFT (Fast Fourier Transform) to embed watermarks in high-frequency regions
• Flexible Region Selection: Choose from corners, center, or random regions for watermark embedding
• Image Watermarks: Embed and extract image-based watermarks
• Text Watermarks: Embed and extract text watermarks with OCR support
• Command Line Interface: Easy-to-use CLI for batch processing
• Multiple Languages: Support for various text languages
• Robust Extraction: High correlation coefficients for reliable watermark detection

Installation

From PyPI (Recommended)

pip install fdwm

From Source

git clone https://github.com/Liam0205/fdwm.git
cd fdwm
pip install -e .

Quick Start

Python API

import cv2
from fdwm import embed, extract, extract_text

# Load host image and watermark
host_img = cv2.imread('host.jpg')
watermark_img = cv2.imread('watermark.png')

# Embed watermark in corners (default)
watermarked_img = embed(host_img, watermark_img, strength=0.1, region_type="corners")

# Embed watermark in center region
watermarked_img = embed(host_img, watermark_img, strength=0.1, region_type="center")

# Embed watermark in random regions with seed
watermarked_img = embed(host_img, watermark_img, strength=0.1, region_type="random", random_seed=42)

# Extract watermark (use same region_type as embedding)
extracted_watermark = extract(watermarked_img, watermark_img.shape[:2], region_type="corners")

# For text watermarks
text = "Hello World"
watermarked_img = embed(host_img, text, strength=0.1, is_text=True, region_type="center")
extracted_text = extract_text(watermarked_img, region_type="center")

Command Line Interface

# Embed image watermark in corners (default)
fdwm embed host.jpg --watermark-img watermark.png

# Embed image watermark in center region
fdwm embed host.jpg --watermark-img watermark.png --region-type center

# Embed image watermark in random regions
fdwm embed host.jpg --watermark-img watermark.png --region-type random --random-seed 42

# Embed text watermark
fdwm embed host.jpg --watermark-text "Hello World" --region-type center

# Extract image watermark (use same region_type as embedding)
fdwm extract watermarked.jpg --region-type center

# Extract text watermark
fdwm extract watermarked.jpg --text --region-type center

Region Types

FDWM supports three different region types for watermark embedding:

1. Corners (Default)

Embeds watermark in the four corners of the image:

• Top-left corner: Main region with full strength
• Bottom-right corner: Flipped watermark with 50% strength
• Top-right corner: Horizontally flipped with 50% strength
• Bottom-left corner: Vertically flipped with 50% strength

This provides good robustness against cropping attacks.

2. Center

Embeds watermark in the center region of the image (30% of image size).

• Provides good resistance to edge cropping
• Maintains watermark integrity in central areas

3. Random

Embeds watermark in random regions using a specified seed:

• Uses 5 random positions by default
• Applies random transformations (flips)
• Requires random_seed parameter for reproducible results
• Provides high security through obfuscation

CLI Usage

Embed Command

fdwm embed <host_image> [options]

Options:
  --watermark-img PATH    Watermark image path
  --watermark-text TEXT   Watermark text
  --strength FLOAT        Embedding strength (default: 30000.0)
  --scale FLOAT           Watermark scale relative to host (default: 0.25)
  --font PATH             Font file path for text watermark
  --font-size INT         Font size for text watermark
  --region-type TYPE      Region type: corners, center, random (default: corners)
  --random-seed INT       Random seed for reproducible random embedding

Extract Command

fdwm extract <watermarked_image> [options]

Options:
  --strength FLOAT        Embedding strength used during embedding (default: 30000.0)
  --scale FLOAT           Watermark scale relative to host (default: 0.25)
  --output PATH           Directory to save extracted watermark images/text
  --text                  Perform OCR and output text instead of image
  --save-text             Save recognized text to .txt files
  --region-type TYPE      Region type used during embedding: corners, center, random (default: corners)
  --random-seed INT       Random seed used during embedding

Examples

Different Region Types

# Embed in corners (most robust)
fdwm embed image.jpg --watermark-text "Secret" --region-type corners

# Embed in center (resistant to edge cropping)
fdwm embed image.jpg --watermark-text "Secret" --region-type center

# Embed in random regions (high security)
fdwm embed image.jpg --watermark-text "Secret" --region-type random --random-seed 12345

# Extract using same region type
fdwm extract watermarked.jpg --text --region-type center

Batch Processing

# Embed watermark in all images in a directory
fdwm embed images/ --watermark-img watermark.png --region-type center

# Extract watermark from all images
fdwm extract watermarked/ --region-type center --output extracted/

Text Watermarking

# Embed Chinese text in center region
fdwm embed image.jpg --watermark-text "Hello World" --region-type center

# Extract text
fdwm extract watermarked.jpg --text --region-type center

Requirements

• Python 3.10+
• numpy
• opencv-python
• Pillow
• pytesseract

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Acknowledgments

• Based on frequency domain watermarking techniques
• Uses OpenCV for image processing
• Tesseract OCR for text extraction