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Update cumulative list of changes from second to third edition #441

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Update cumulative list of changes from second to third edition #441

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0f53b3e
Update cumulative list of changes from second to third edition
svgeesus Mar 22, 2024
fb6e0dd
grammar
svgeesus Mar 22, 2024
414825b
Add order of precedence for color space chunks
svgeesus Mar 22, 2024
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67 changes: 52 additions & 15 deletions index.html
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Expand Up @@ -7713,36 +7713,73 @@ <h3 id="changes-20031110">Changes since the <a href="https://www.w3.org/TR/2003/
Second Edition)</h3>

<ul>
<!-- to 5 Apr 2022 -->
<!-- to 22 March 2024 -->

<li>
<p>The three previously defined, but unofficial, chunks for Animated PNG (APNG) have been added:</p>

<ul>
<li><a href="#acTL-chunk" class="chunk">acTL</a> Animation Control Chunk</li>
<li><a href="#fcTL-chunk" class="chunk">fcTL</a> Frame Control Chunk</li>
<li><a href="#fdAT-chunk" class="chunk">fdAT</a> Frame Data Chunk</li>
</ul>

<p>This brings the PNG specification into alignment with widely deployed industry practice.</p>
</li>

<li>
<p>Added the <a class="chunk" href="#cICP-chunk">cICP</a> 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
(<a>HDR</a>) and Wide Color Gamut (WCG) images.</p>
</li>

<li>
<p>For chunks which define the image color space,
the order of precedence is clearly defined,
if more than one is present.</p>
</li>

<li>The three previously defined, but unofficial, chunks for APNG have been added. This brings the PNG specification
into alignment with widely deployed industry practice.
<li>
<p>The previously defined <a class="chunk" href="#eXIf">eXIf</a> chunk has been moved from the PNG-Extensions document
[[PNG-EXTENSIONS]] into the main body of this specification, to reflect its increasing use.</p>
</li>

<li>Added the <a class="chunk" href="#cICP-chunk">cICP</a> 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
(<a>HDR</a>) and Wide Color Gamut (WCG) images.
<li>
<p>To help with tonemapping HDR content, added the <a class="chunk" href="#mDCv-chunk">mDCv</a> chunk, which contains metadata about the display used in
mastering, and <a href="#cLLi-chunk" class="chunk">cLLi</a>, which contains metadata about peak and average light levels. This enabled more accurate color matching on heterogeneous platforms</p>
</li>

<li>
<p>Clarified that the <a href="#11iCCP" class="chunk">iCCP</a> 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.</p>
</li>

<li>The previously defined <a class="chunk" href="#eXIf">eXIf</a> chunk has been moved from the PNG-Extensions document
[[PNG-EXTENSIONS]] into the main body of this specification, to reflect it's widespread use.
<li>
<p>Clarified handling of out-of-range indexes, for indexed-color PNG</p>
</li>

<li>Added the <a class="chunk" href="#mDCv-chunk">mDCv</a> chunk, which contains metadata about the display used in
mastering. This enabled more accurate color matching on heterogeneous platforms
<li>
<p>Clarified error recovery for unknown and invalid ancillary chunks</p>
</li>

<li>Incorporation of all <a href="https://www.w3.org/2003/11/REC-PNG-20031110-errata">PNG Second Edition Errata</a>
<li>
<p>Incorporation of all <a href="https://www.w3.org/2003/11/REC-PNG-20031110-errata">PNG Second Edition Errata</a>. Notably, clarified that PNG images with unknown gamma value, when embedded in formats such as HTML or SVG, must be treated as <a href="https://drafts.csswg.org/css-color-4/#untagged">untagged images</a></p>
</li>

<li>Various editorial clarifications in response to community feedback</li>
<li>
<p>Various editorial clarifications in response to community feedback</p>
</li>

<li>References updated to latest versions</li>
<li>
<p>References updated to latest versions</p>
</li>

<li>Markup corrections and link fixes</li>
<li>
<p>Markup corrections and link fixes</p>
</li>

<li>Document source reformatted to use ReSpec</li>
<li>
<p>Document source reformatted to use ReSpec</p>
</li>
</ul>

<h3>Changes between First and Second Editions</h3>
Expand Down