The History of the PNG Format: From Patent Battles to Modern Web Standards
PNG (Portable Network Graphics) is one of the most widely used and trusted image formats on the web. Today, it powers logos, icons, game textures, and even animated stickers. But its origin story isn’t about technology — it’s about patent disputes, open-source activism, and the fight for a free internet. In this article, we explore the full evolution of PNG — from its creation as a GIF alternative to its modern support for HDR and animation.
Why PNG Was Created: The End of GIF’s Dominance
In the mid-1990s, GIF was the dominant format for web images. Developed by CompuServe in 1987, it offered lossless compression and animation support. However, its core compression algorithm — LZW — was patented by Unisys. Despite being widely used, developers faced legal risks: Unisys began enforcing licensing fees for software using LZW compression.
This sparked outrage in the open-source community. In 1999, the campaign “Burn All GIFs” urged developers to abandon GIF due to patent concerns. The web needed a free, open, and technically superior alternative.
The solution came from developer Thomas Boutell. On January 4, 1995, he published a draft of a new format initially called PBF (Portable Bitmap Format). By January 23, it was renamed PNG — short for “Portable Network Graphics”, but also a playful recursive acronym: “PNG’s Not GIF”.
The goal was clear: create a patent-free, open, and future-proof image format for the web. And so, the era of PNG began.
Technical Advantages: Why PNG Outperformed GIF
PNG was designed to be more efficient, flexible, and higher quality than GIF. It uses the DEFLATE compression algorithm (a combination of LZ77 and Huffman coding), which is 10–25% more efficient than LZW, resulting in smaller file sizes with no quality loss.
Data in PNG is stored in modular blocks called chunks, each with a type, data, and CRC checksum. This design allows future extensions without breaking compatibility.
Key technical advantages of PNG:
- Alpha channel transparency — 256 levels of partial transparency (vs. GIF’s binary transparency).
- Truecolor support — up to 48 bits per pixel (16 million colors).
- Gamma correction — ensures consistent brightness across devices.
- Interlacing — allows progressive rendering during download.
PNG vs GIF: A Comparative Overview
| Feature | PNG | GIF |
|---|---|---|
| Compression Algorithm | DEFLATE | LZW |
| Patent Status | Open, royalty-free | Patented (expired 2003–2006) |
| Color Depth | Up to 48-bit (Truecolor) | Up to 8-bit (256 colors) |
| Transparency | Alpha channel (256 levels) | Binary (on/off) |
| Animation | APNG (since 2025) | Built-in support |
| Best For | Logos, icons, text, graphics with transparency | Simple animations, diagrams |
Standardization and Evolution: From W3C to ISO
PNG’s development was formalized through collaboration with major standards bodies. In 1996, the World Wide Web Consortium (W3C) officially recognized PNG as a Recommendation, making it the only raster format endorsed for the web.
In 1998, it was adopted as an international standard: ISO/IEC 15948, confirming its long-term reliability.
The most significant update came in 2025 with the third edition of the specification, introducing three major extensions:
- HDR (High Dynamic Range) — support for metadata chunks like
mDCV,cLLI, andcICPfor accurate brightness and color gamut. - APNG (Animated PNG) — native animation via chunks
acTL,fcTL,fdAT. - EXIF Metadata — embedding camera and exposure data via the
eXIfchunk.
The PNG Working Group at W3C continues development, with a mandate extended to 2026, and plans for a fourth edition of the standard.
Key Contributors and Organizations Behind PNG
PNG was a collaborative effort by developers, engineers, and standards organizations. Here are the main contributors:
| Role | Name / Organization | Contribution |
|---|---|---|
| Creator | Thomas Boutell | Initiated the project, authored the first specification |
| Library Developers | Jean-loup Gailly, Mark Adler, Guy Eric Schalnat | Created zlib and libpng (May 1, 1995) |
| Standards Body | W3C | Official standardization, ongoing working group |
| W3C Leadership | Chris Blume (Chair), Chris Lilley (Contact) | Lead the PNG Working Group |
| International Standard | ISO / IEC | Certified PNG as ISO/IEC 15948 |
Modern Use Cases: Where PNG Shines Today
Today, PNG is far more than a GIF replacement. It’s a versatile format used across industries:
- Web Design: Logos, icons, buttons with transparent backgrounds.
- Messaging Apps: Animated stickers (APNG) in Telegram, Discord, and others.
- Gaming: Textures in Unreal Engine and Unity.
- AR/VR & AI: High-precision masks, labels, and training data.
However, PNG is not ideal for photographs — its files are larger than JPEG, WebP, or AVIF. Use it for graphics with sharp edges, text, or transparency.
PNG’s biggest strength? Universal support. It works in every browser, OS, and image editor. This makes it the perfect fallback format and a symbol of reliability.
The Future of PNG: Embracing HDR and Beyond
The future of PNG is bright. With support for HDR, APNG, and EXIF, it now competes with modern formats like WebP and AVIF.
HDR support enables use in professional photography, film, and medical imaging. APNG offers smooth, high-color animations. EXIF metadata turns PNG into a complete photo container.
The W3C working group continues evolving the standard, ensuring PNG remains relevant for decades.
Conclusion: PNG is more than a file format. It’s a symbol of the open web — born from a patent dispute, built by a global community, and evolving to meet the needs of modern digital media. As long as clarity, transparency, and openness matter, PNG will remain essential.
Stay tuned to W3C and ISO updates — the best may still be ahead for PNG.
