From 0f53b3e39518db1a23205901109c19e9bb724a8c Mon Sep 17 00:00:00 2001 From: Chris Lilley Date: Fri, 22 Mar 2024 10:30:45 -0400 Subject: [PATCH 1/3] Update cumulative list of changes from second to third edition --- index.html | 61 ++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 46 insertions(+), 15 deletions(-) diff --git a/index.html b/index.html index 9376625..174c64f 100644 --- a/index.html +++ b/index.html @@ -7713,36 +7713,67 @@

Changes since the acTL Animation Control Chunk +
  • fcTL Frame Control Chunk
    • +
  • fdAT Frame Data Chunk
    • + + +

    This brings the PNG specification into alignment with widely deployed industry practice.

    + + +
  • +

    Added the cICP chunk, Coding-independent code points for video signal type + identification, to contain image format metadata defined in [[ITU-T-H.273]] which enables PNG to contain [[ITU-R-BT.2100]] High Dynamic Range + (HDR) and Wide Color Gamut (WCG) images.

    +
    • -
  • The three previously defined, but unofficial, chunks for APNG have been added. This brings the PNG specification - into alignment with widely deployed industry practice. +
  • +

    The previously defined eXIf chunk has been moved from the PNG-Extensions document + [[PNG-EXTENSIONS]] into the main body of this specification, to reflect it's increasing use.

    • -
  • Added the cICP chunk, Coding-independent code points for video signal type - identification, to contain image format metadata defined in [[ITU-T-H.273]] which enables PNG to contain [[ITU-R-BT.2100]] High Dynamic Range - (HDR) and Wide Color Gamut (WCG) images. +
  • +

    To help with tonemapping HDR content, added the mDCv chunk, which contains metadata about the display used in + mastering, and cLLi, which contains metadata about peak and average light levels. This enabled more accurate color matching on heterogeneous platforms

    +
    • +
  • +

    Clarified that the iCCP chunk, which contains an ICC profile, can contain profiles conforming to any version of the ICC.1 specification. PNG Second Edition only referenced the then-current v2 of ICC.1, although it has since become industry practice to also used higher versions.

    • -
  • The previously defined eXIf chunk has been moved from the PNG-Extensions document - [[PNG-EXTENSIONS]] into the main body of this specification, to reflect it's widespread use. +
  • +

    Clarified handling of out-of-range indexes, for indexed-color PNG

    • -
  • Added the mDCv chunk, which contains metadata about the display used in - mastering. This enabled more accurate color matching on heterogeneous platforms +
  • +

    Clarified error recovery for unknown and invalid ancillary chunks

    • -
  • Incorporation of all PNG Second Edition Errata +
  • +

    Incorporation of all PNG Second Edition Errata. Notably, clarified that PNG images with unknown gamma value, when embedded in formats such as HTML or SVG, must be treated as untagged images

    • -
  • Various editorial clarifications in response to community feedback
    • +
  • +

    Various editorial clarifications in response to community feedback

    +
    • -
  • References updated to latest versions
    • +
  • +

    References updated to latest versions

    +
    • -
  • Markup corrections and link fixes
    • +
  • +

    Markup corrections and link fixes

    +
    • -
  • Document source reformatted to use ReSpec
    • +
  • +

    Document source reformatted to use ReSpec

    +

    • Changes between First and Second Editions

    From fb6e0dd49e95d1f26e5bfd189d486bdd1c45fe80 Mon Sep 17 00:00:00 2001 From: Chris Lilley Date: Fri, 22 Mar 2024 14:08:32 -0400 Subject: [PATCH 2/3] grammar Co-authored-by: Chris Needham --- index.html | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/index.html b/index.html index 174c64f..2228a1e 100644 --- a/index.html +++ b/index.html @@ -7735,7 +7735,7 @@

    Changes since the eXIf chunk has been moved from the PNG-Extensions document - [[PNG-EXTENSIONS]] into the main body of this specification, to reflect it's increasing use.

    + [[PNG-EXTENSIONS]] into the main body of this specification, to reflect its increasing use.

  • From 414825ba2e1c40775b9785d41064f83a03ed41d3 Mon Sep 17 00:00:00 2001 From: Chris Lilley Date: Fri, 22 Mar 2024 14:16:12 -0400 Subject: [PATCH 3/3] Add order of precedence for color space chunks --- index.html | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/index.html b/index.html index 2228a1e..a86dcd1 100644 --- a/index.html +++ b/index.html @@ -7733,6 +7733,12 @@

    Changes since the eXIf chunk has been moved from the PNG-Extensions document [[PNG-EXTENSIONS]] into the main body of this specification, to reflect its increasing use.