Image Extractor

A tool for extracting and repacking PNG files from .fnt and .spranm formats in DOKAPON! Sword of Fury.

Table of contents

  1. Overview
  2. Requirements
  3. Installation
  4. Usage
    1. Extracting Images
    2. Reimporting Images
  5. Output Structure
    1. Extracted Files
    2. JSON Metadata Format
  6. Technical Details
    1. File Format Analysis
      1. FNT/SPRANM Structure
    2. Extraction Process
    3. Import Process
    4. Memory Management
  7. Best Practices
  8. Troubleshooting
    1. Common Issues
  9. Contributing
  10. License

Overview

The Image Extractor (all2image.py) is a Python script that allows you to:

  • Extract PNG files from the game’s .fnt and .spranm formats
  • Repack modified PNG files back into their original formats
  • Preserve file structure and metadata for accurate repacking

Requirements

  • Python 3.6 or higher
  • DOKAPON! Sword of Fury (PC Version) installed
  • Basic knowledge of using command line tools

Installation

  1. Download the all2image.py script
  2. Place it in the directory containing your .fnt or .spranm files

Usage

The tool provides an interactive menu-driven interface with the following options:

  1. Extract PNG from .fnt files only
  2. Extract PNG from .spranm files only
  3. Extract PNG from both .fnt and .spranm
  4. Reinsert (import) PNG using a JSON metadata file
  5. Exit the program

Extracting Images

  1. Run the script:
    python all2image.py
  2. Choose the appropriate extraction option (1-3)
  3. Either:
    • Press Enter to process all matching files in the current directory
    • Type specific filenames separated by spaces

The script will:

  1. Create an output directory (extracted_fnt or extracted_spranm)
  2. Extract PNG files
  3. Generate JSON metadata files for each extraction

Reimporting Images

  1. Choose option 4 from the main menu
  2. Provide:
    • Path to the JSON metadata file
    • Path to your modified PNG file
    • Output filename (or press Enter for default name)

Output Structure

Extracted Files

extracted_fnt/
  ├── font1.png
  ├── font1.png.json
  ├── font2.png
  └── font2.png.json

JSON Metadata Format

{
    "original_file": "/absolute/path/to/original.fnt",
    "offset": 1234,
    "length": 5678
}

Technical Details

File Format Analysis

FNT/SPRANM Structure

Both file formats embed PNG data with:

  • Standard PNG signature (89 50 4E 47 0D 0A 1A 0A)
  • Complete PNG data including IEND chunk
  • Additional game-specific metadata

Extraction Process

  1. PNG Signature Detection
    PNG_SIGNATURE = b'\x89PNG\r\n\x1a\n'
start_index = data.find(PNG_SIGNATURE)
  2. End Marker Location
    PNG_IEND = b'IEND\xaeB`\x82'
end_index = data.find(PNG_IEND, start_index) + len(PNG_IEND)
  3. Data Extraction
    png_data = data[start_index:end_index]

Import Process

The tool handles size differences between original and modified PNGs:

  1. Smaller Files
    • Adds null byte padding to match original size
    • Preserves file structure integrity
  2. Larger Files
    • Issues warning about size difference
    • Truncates data to fit original space
    • Prevents buffer overflows

Memory Management

  • Streams large files in chunks
  • Efficient byte manipulation
  • Minimal memory footprint

Best Practices

  1. Before Extraction
    • Back up original files
    • Ensure sufficient disk space
    • Verify file permissions
  2. Image Modification
    • Maintain original PNG dimensions
    • Keep file size similar to original
    • Test modifications thoroughly
  3. Reimporting
    • Always work with copies
    • Keep original JSON metadata
    • Verify successful imports

Troubleshooting

Common Issues

  1. PNG Not Found
    [file.fnt] PNG signature not found.
    • Verify file is correct format
    • Check file isn’t corrupted
  2. Import Size Mismatch
    Warning: New PNG data is larger than the original space
    • Reduce modified PNG file size
    • Optimize PNG compression

Contributing

Found a bug or want to improve the tool?

  • Report issues on GitHub
  • Submit pull requests with improvements
  • Share your findings on our Discord

License

This tool is licensed under The Unlicense. You can:

  • ✅ Use freely for any purpose
  • ✅ Modify and distribute without restrictions
  • ✅ No attribution required
  • ✅ Dedicated to public domain
  • ✅ No warranty provided

See the LICENSE file for full details.