Re: [EXTERNAL] Re: Conformance files in PQ, HLG, SDR-BT.709?

You’re not going to believe this, but Apple Compressor and FinalCut already recognizing the CICP Chunk correctly (with the exception of full-range flag).

-Chris



From: Chris Lilley <chris@w3.org>
Date: Friday, December 8, 2023 at 3:54 PM
To: Seeger, Chris (NBCUniversal) <Chris.Seeger@nbcuni.com>, public-png@w3.org <public-png@w3.org>
Subject: Re: [EXTERNAL] Re: Conformance files in PQ, HLG, SDR-BT.709?

Sorry I was in a rush to get to another meeting, meant to add the link, forgot

The page is here:
  https://www.nayuki.io/page/png-file-chunk-inspector<https://urldefense.com/v3/__https:/www.nayuki.io/page/png-file-chunk-inspector__;!!PIZeeW5wscynRQ!qsxmSbvqc4A7IuUQxfIlRxReb1_9TKnUmESzCkfxEdPBHx23PKB55Ml6lSuM1-lvlrAgcMvMf2cb8A$>

source is here:
  https://github.com/nayuki/Nayuki-web-published-code/tree/master/png-file-chunk-inspector<https://urldefense.com/v3/__https:/github.com/nayuki/Nayuki-web-published-code/tree/master/png-file-chunk-inspector__;!!PIZeeW5wscynRQ!qsxmSbvqc4A7IuUQxfIlRxReb1_9TKnUmESzCkfxEdPBHx23PKB55Ml6lSuM1-lvlrAgcMtpNW-Nqg$>

my unofficial extension to that code to add cICP support is very simple
["cICP", "Coding-independent code points ", false, (chunk, earlier) => {
            addErrorIfHasType(earlier, "PLTE", chunk, "Chunk must be before PLTE chunk");
            addErrorIfHasType(earlier, "IDAT", chunk, "Chunk must be before IDAT chunk");
            if (chunk.data.length != 4) {
                chunk.errorNotes.push("Invalid data length");
                return;
            }
            const chromaticities = chunk.data[0];
            const transfer = chunk.data[1];
            const matrix = chunk.data[2];
            const videowidth = chunk.data[3];
            if (matrix !== 0) {
                chunk.errorNotes.push("PNG only supports RGB data");
            }
            if (videowidth > 1) {
                chunk.errorNotes.push("Undefined video width value, must be narrow or full");
            }
            // look for specific, common combination values first
            if (chromaticities === 1) {
                // HDTV or sRGB
                if (transfer === 1) {
                    chunk.innerNotes.push(`Rec BT.709 HDTV`);
                } else if (transfer === 8) {
                    chunk.innerNotes.push(`Linear-light sRGB`);
                } else if (transfer === 13) {
                    chunk.innerNotes.push(`IEC 61966-2-1 sRGB`);
                }
            } else if (chromaticities === 9) {
                // BT.2020 or BT.2100
                if (transfer === 14) {
                    chunk.innerNotes.push(`Rec. ITU-R BT.2020-2 (10-bit system)`);
                } else if (transfer === 15) {
                    chunk.innerNotes.push(`Rec. ITU-R BT.2020-2 (12-bit system)`);
                } else if (transfer === 16) {
                    chunk.innerNotes.push(`Rec. ITU-R BT.2100-2 (PQ system)`);
                } else if (transfer === 18) {
                    chunk.innerNotes.push(`Rec. ITU-R BT.2100-2 (HLG system)`);
                };
                // Only mention narrow or full range if both are actually options
                if (videowidth === 0) {
                    chunk.innerNotes.push(`Narrow Range`);
                } else {
                    chunk.innerNotes.push(`Full Range`);
                };
            } else if (chromaticities === 12) {
                // SMPTE EG 432-1 (2010) - DCI D65
                if (transfer === 13) {
                    // Display-P3 uses sRGB transfer function
                    chunk.innerNotes.push(`Display-P3`);
                }
            }
            else {
                // Not common combination
                let c, t, m, p;
                c = chromaticities.toString();
                chunk.innerNotes.push(`Chromaticity: ${c}`);
                t = transfer.toString();
                chunk.innerNotes.push(`Transfer: ${t}`);
                m = (matrix === 0) ? "RGB" : "YCC";
                chunk.innerNotes.push(`Matrix: ${m}`);
                p = (videowidth === 0) ? "Narrow" : "Wide";
                chunk.innerNotes.push(`videowidth: ${p}`);
            }
        }],
On 2023-12-08 14:08, Seeger, Chris (NBCUniversal) wrote:
Do you have a link to it 😊

Also, did I mention that MediaInfo now has support in their nightly build (I’ve been sending out too many emails this morning).

https://mediaarea.net/download/snapshots/binary/mediainfo-gui/<https://urldefense.com/v3/__https:/mediaarea.net/download/snapshots/binary/mediainfo-gui/__;!!PIZeeW5wscynRQ!qsxmSbvqc4A7IuUQxfIlRxReb1_9TKnUmESzCkfxEdPBHx23PKB55Ml6lSuM1-lvlrAgcMtJSyeBsw$>

-Chris


From: Chris Lilley <chris@w3.org><mailto:chris@w3.org>
Date: Friday, December 8, 2023 at 1:53 PM
To: public-png@w3.org<mailto:public-png@w3.org> <public-png@w3.org><mailto:public-png@w3.org>
Subject: Re: [EXTERNAL] Re: Conformance files in PQ, HLG, SDR-BT.709?

There is a nice PNG file chunk inspector, all written in JavaScript

I took a copy and extended it to support cICP. Here is a screenshot of the output. I recognize the most common color spaces and output their names, otherwise I output the actual data.

[cid:part1.snFFGzUD.oGMQQbeO@w3.org]

--

Chris Lilley

@svgeesus

Technical Director @ W3C

W3C Strategy Team, Core Web Design

W3C Architecture & Technology Team, Core Web & Media

--

Chris Lilley

@svgeesus

Technical Director @ W3C

W3C Strategy Team, Core Web Design

W3C Architecture & Technology Team, Core Web & Media