pngmeta 0.1.0

A Python library for reading and writing PNG metadata (tEXt, iTXt, zTXt chunks and XMP)

pngmeta

A Python library for reading and writing PNG metadata, similar to iptcinfo3 for JPEG files.

Features

• Read and write PNG text chunks (tEXt, iTXt, zTXt)
• Handle XMP metadata in PNG files
• Simple, intuitive API similar to iptcinfo3
• Pure Python implementation with no dependencies
• Support for UTF-8 and compressed text chunks

Installation

pip install pngmeta

Or with uv:

uv pip install pngmeta

Quick Start

from pngmeta import PngMeta

# Read metadata
meta = PngMeta('image.png')
print(meta.get('Title'))
print(meta.get('Author'))
print(meta.get('Copyright'))

# Write metadata
meta.set('Title', 'My Image')
meta.set('Author', 'John Doe')
meta.set('Copyright', 'Copyright 2025')
meta.save()

# Save to a new file
meta.save('image_with_metadata.png')

# Work with XMP
xmp = meta.get_xmp()
if xmp:
    print("XMP data:", xmp)

# Dictionary-style access
meta['Description'] = 'A beautiful landscape'
if 'Author' in meta:
    print(f"Author: {meta['Author']}")

# Iterate over all metadata
for key, value in meta.items():
    print(f"{key}: {value}")

Common PNG Text Keywords

• Title - Short title or caption
• Author - Image author
• Description - Longer description
• Copyright - Copyright notice
• Creation Time - Original image creation time
• Software - Software used to create the image
• Comment - Miscellaneous comment
• XML:com.adobe.xmp - XMP metadata (automatically handled)

PNG Metadata Background

PNG files store metadata in "ancillary chunks":

• tEXt - Latin-1 text (uncompressed)
• iTXt - UTF-8 text (optionally compressed), used for XMP
• zTXt - Compressed Latin-1 text

Unlike JPEG, PNG doesn't natively use IPTC, but XMP can be embedded in iTXt chunks for cross-format compatibility.

Development

# Clone the repository
git clone https://github.com/yourusername/pngmeta.git
cd pngmeta

# Install with uv
uv venv
source .venv/bin/activate  # or `.venv\Scripts\activate` on Windows
uv pip install -e ".[dev]"

# Run tests
pytest

# Format code
black pngmeta tests

# Type checking
mypy pngmeta

License

This is free and unencumbered software released into the public domain (Unlicense).

See Also

• iptcinfo3 - IPTC metadata for JPEG files
• PNG Specification
• Exiv2 PNG Metadata Notes