SUMM

Discusses the importance of image formats and serving optimal assets to users
Points out PNG's strengths, but highlights its age and lack of features like animation, strong compression, and HDR support
Announces a major update to the PNG specification after over 20 years
Brief pause for a sponsor message promoting Blacksmith, a tool promising faster, cheaper GitHub builds with benefits such as up to 75% cost reduction and improved caching

The last PNG specification was released over 20 years ago, before the first iPhone
Technological advances and new requirements (notably, HDR subtitles from W3C) prompted a revival of the PNG standard
A broad coalition including Adobe, Apple, Google, BBC, and W3C worked on the new spec, with ongoing work for future editions
PNG remains widely recommended for archiving by institutions like the US Library of Congress due to its preservation qualities

For distribution and everyday web use, formats like WEBP and AVIF are often better due to much smaller file sizes and acceptable quality
Lossy formats are preferred for user-facing images to save bandwidth and speed up apps, with original PNGs reserved for downloads or archival
Using PNG for bulk image serving would dramatically increase sizes (e.g., 8.3 KB WEBP vs. 3.8 MB original PNG), making it impractical for high-volume usage

Major change: PNG now supports proper HDR (High Dynamic Range), allowing more vivid brights, deeper blacks, and a wider color range
Previous PNGs could not preserve HDR data; now this is possible using only four additional bytes plus standard overhead
HDR support involves specifying color space information and transfer characteristics according to standards (e.g., Rec 2020, BT.2100 for HDR, CICP labeling)
The HDR features are designed for backward compatibility, so older platforms just display them as standard images

Explanation of how color perception works, and how data is encoded in images (using XYZ and chromaticity values)
Color spaces like Rec 709 (cinema), Rec 2020 (HDR), and sRGB remain important, with platforms needing to know which space to use for accurate reproduction
CICP labeling in PNG allows easy identification of color space for compatibility across platforms and archives
Proper HDR allows for dramatically improved visuals on capable screens, with techniques like hybrid log gamma (HLG) used in live broadcasts and modern smartphones

APNGs have now been adopted into the official PNG specification, solving longstanding compatibility and standardization issues
APNG is valuable for lossless animated image transfer with full transparency (unlike GIF, which is neither efficient nor truly lossless)
Lossless animation formats like APNG are mainly intended for production and archival purposes, not everyday user-facing delivery
Warns against excessive usage of lossless formats for general consumption, advocating for compressed formats whenever possible

PNGs can now carry EXIF metadata (e.g., camera settings, embedded information), which previously was stripped during conversion
The update brings PNG in line with modern expectations for image metadata support

The spec is designed to be backward compatible, and many popular programs and platforms already support the new PNG features (Chrome, Safari, Firefox, iOS/Mac OS, Photoshop, Da Vinci Resolve, Avid Media Composer)
Broadcast infrastructure is adopting the format, leveraging HDR features in news tickers and overlays

Upcoming PNG updates (fourth and fifth editions) are already planned: goals include improved compression and faster parallel encoding/decoding
Next update will focus on better HDR and SDR interoperability
Compression improvements are particularly anticipated to address PNG's current inefficiencies compared to newer formats

The update to PNG is a significant and highly positive change, especially for those managing media and archival content
The host expresses excitement for continued updates and shouts out contributors and the technical community for their work on the new spec

20 years later, PNG 3.0 is finally here