PNG Metadata Editor v2.3.0

A graphical tool for viewing and editing metadata in PNG files with an intuitive image browser interface.

Features

Core Features

• View all metadata fields (tEXt, zTXt, iTXt chunks) in PNG files
• Add, edit, and delete metadata fields
• Copy metadata values to clipboard
• Visual indication of unsaved changes
• Pretty-print JSON values in editor (auto-flattens on save)

Image Browser

• Browse directories with thumbnail previews
• Auto-scroll to selected images
• Trackpad and mousewheel scrolling support
• Smooth navigation between multiple files

User Interface

• Automatic dark mode detection (macOS, Windows, Linux)
• Adaptive canvas background based on system theme
• Unicode support throughout UI
• Resizable panes for optimal workflow

Technical Improvements

• Smart JSON handling: displays formatted, saves flattened
• Proper file handle management for reliable multi-file loading
• Enhanced scroll region updates for smooth browsing

Installation

Prerequisites

• Python 3.6+
• Tkinter (usually included with Python)

Dependencies

Install required packages using pip:

pip install pillow

Usage

Basic Workflow

1. Run the application:

   python png-meta-editor.py
   

2. Browse Directory: Click "Browse Directory" to load thumbnails from a folder

3. Select Image: Click any thumbnail to load its metadata

4. View Metadata: See all fields in the tree view with preview

5. Edit Fields:

   • Double-click or use "Edit Field" to modify values
   • JSON values display formatted but save flattened

6. Save Changes: Click "Save Changes" to write metadata back to file

Keyboard Shortcuts

• Double-click on tree item to edit
• Enter/Escape in dialogs to confirm/cancel

Dark Mode

The application automatically detects your system theme:

• macOS: Reads AppleInterfaceStyle setting
• Windows: Reads personalization registry settings
• Linux: Checks GTK theme preferences

Building for Distribution

Using build.py (Recommended)

1. First install the required build tools:

   pip install pyinstaller
   

2. Build the application for your platform:

   python build.py
   

3. The resulting executable will be in the dist/ directory

Manual PyInstaller Commands

Windows

pyinstaller --name="PNG Metadata Editor" \
            --windowed \
            --onefile \
            --icon=AppIcon.ico \
            --version-file version.txt \
            png-meta-editor.py

macOS

pyinstaller --name="PNG Metadata Editor" \
            --windowed \
            --onefile \
            --icon=AppIcon.icns \
            --version-file version.txt \
            png-meta-editor.py

Linux

pyinstaller --name="PNG Metadata Editor" \
            --windowed \
            --onefile \
            png-meta-editor.py

Required Files

For building, you'll need:

• version.txt (for version information)
• AppIcon.ico (Windows icon)
• AppIcon.icns (Mac icon)
• requirements.txt (for dependencies)

Technical Details

JSON Handling

The editor intelligently handles JSON metadata:

• Display: Pretty-printed with indentation for readability
• Storage: Automatically flattened to single line to preserve original format
• Example:

  // What you see in editor:
  {
    "prompt": "a cat",
    "steps": 20
  }
  
  // What gets saved:
  {"prompt":"a cat","steps":20}
  

File Management

• Proper file handle release after reading metadata
• Supports loading multiple files sequentially without issues
• Thumbnail caching for smooth browsing experience

License

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

Author

Robert Tusa
robert@tusa.at

Version History

v2.3.0 (2026-01-07) - Major UI Update

• Added image browser with thumbnail previews
• Implemented dark mode detection for all platforms
• Added trackpad/mousewheel scrolling support
• Smart JSON flattening (preserves original format)
• Fixed file loading issues with proper handle management
• Enhanced scroll region updates
• Unicode support in UI elements

v1.0.0 (2026-01-05) - Initial Release

• Basic metadata viewing and editing
• Tree view with detail pane
• Add, edit, delete operations
• JSON pretty-printing