After 20 Years of Nothing, PNG Now Updates Every Year

A Quick Recap - What Changed in PNG Edition 3

If you missed our earlier coverage, the W3C published the PNG Third Edition in June 2025 - the first major update to the format since 2003. The headline additions were HDR support, official APNG (Animated PNG) recognition, and formal EXIF metadata support.

Major browsers and apps already support those features: Chrome, Safari, Firefox, iOS/macOS, Photoshop, and DaVinci Resolve all shipped compatibility before or shortly after the spec was published. The update was backed by a broad industry coalition including Adobe, Apple, Google, BBC, Comcast/NBCUniversal, and MovieLabs.

Did you know? The push to update PNG originally came from subtitle and caption makers. The W3C's Timed Text Working Group needed HDR support in PNG images so that bright subtitles wouldn't cause eye strain against dark scenes. That narrow requirement opened the door to a full format overhaul.

PNG 4th Edition - What's Being Added Now

The 4th Edition Editor's Draft is already live at the W3C GitHub repository as of early 2026. It's still in development, but the key additions are already well-defined.

The headline feature is gain maps. You may have encountered this term with HEIC photos from Apple devices. A gain map is a small piece of extra data embedded in an image that tells the display how to tone-map HDR content when shown on a standard SDR screen.

In plain terms: your HDR photo will look great on a 4K HDR monitor and still look correct on an older laptop screen - automatically, with no manual export step. The Working Group has acknowledged that gain maps add some overhead to file size, but considers the trade-off worthwhile.

The 4th Edition is also described as a "short" update - focused tightly on HDR/SDR interoperability rather than sweeping changes. Expect a faster publication timeline than the 22-year gap between editions 2 and 3.

PNG 5th Edition - Finally Tackling File Size

The 5th Edition is the one that could genuinely shake up the image format landscape. The Working Group has set out to research three major compression improvements.

• Updated libpng - the core library hasn't kept pace with modern hardware capabilities
• Parallel encoding and decoding - current PNG processes images sequentially, leaving modern multi-core CPUs mostly idle during large batch jobs
• Modern compression algorithms - the leading candidate is zstd (Zstandard), the same algorithm used in many modern archive formats, which can compress faster and smaller than PNG's current DEFLATE method

File size has always been the weakness that pushed developers toward WebP and AVIF. If the 5th Edition ships meaningful compression gains while keeping PNG's lossless quality and universal compatibility, the format could close that gap significantly.

What This Means for Your Images Right Now

For most users, nothing changes today. The 4th and 5th Editions are still in development and won't ship overnight. But if you're already working with PNG images, it's worth optimizing what you have now.

For batch-converting or processing PNG files on Windows, XnConvert handles 500+ formats with 80+ operations per file - resize, recolor, strip metadata, and export in one pass. IrfanView is another strong choice for quick batch tasks and metadata inspection.

If you need to reduce PNG file sizes without losing transparency or quality right now - before the 5th Edition arrives - OptimizePNG is a free online tool that compresses PNG files by up to 80% directly in your browser, no install required. You can also inspect or strip EXIF and chunk metadata from any PNG using the OptimizePNG Metadata Viewer - useful now that EXIF is officially part of the PNG spec.

The Bigger Picture - PNG vs. WebP vs. AVIF

The 3rd Edition already addressed the feature gap between PNG and modern formats like AVIF. The 5th Edition targets the last remaining weakness: file size.

PNG's advantages - lossless quality, universal compatibility, zero patent encumbrances, and now HDR support - have always been strong. If compression catches up, there's a real case for PNG becoming the default choice again for web assets that need transparency.

For now, FastStone Image Viewer and most modern image tools already handle the 3rd Edition features without any extra steps. The format is moving forward faster than at any point in its 30-year history.