PNG Progress

PNG History

1994-1996

PNG created, developed & standardized

1996-2003

PNG widely adopted

PNG Second Edition, ISO standard

2004-2023

(crickets)

2007

Animated PNG proposed, rejected

PNG Working Group (2021)

• Maintain PNG spec (clarifications, errata)
• Incorporate APNG
• Extend for WCG & HDR

Wide Color Gamut

Defines color space of the RGB image data

• ICC Profiles (PNG 2nd Edition)
  • Adds 1-20 kB
• CICP (PNG 3rd Edition)
  • Adds 4 bytes

High Dynamic Range

Difference in luminance between the lightest and the darkest colors, in stops (log scale)

HDR has deeper darks, brighter lights than reference white ("paper white").

Content Luminance Levels

Helps with tone mapping for less capable screens

MaxFALL

Average luminance level of the brightest frame

MaxCLL

Luminance of the brightest pixel

Mastering Color Volume

Helps with tone mapping and gamut mapping

Mastering display gamut and maximum luminance sets an upper bound on the range of colors in the content.

HDR10

CICP + CLLI + MDCV = HDR10

PNG fits in existing HDR workflow

PNG 4th Edition

• Content Credentials
• just started, but expected to be a small update