Implement CICP Chunk described in PNG 3rd Edition (Priority 1)

[digitaltvguy]

The CICP Chunk identifies explicit characteristics of an image which is described in H.273. CICP is used in every video wrapper and in many codecs to identify the images contained in every framer.

Without this HDR/SDR/WCG (High Dynamic Range, Standard Dynamic Range and Wide Color Gamut) images using BT.709, BT.2100 can't be identified properly.

Identification is critical for content creation described in ITU-R BT.2408 (single-master UHD workflows). The new CICP chunk gives new support for

[jbowler]

Spamming the issues list seems inappropriate.

[digitaltvguy]

Sorry, I thought I was doing what you requested, describing the specific issues. *************** “Believe me it's a lot of work. I can suggest other approaches but it's off topic for this issue which, well, what is the issue @digitaltvguy<https://urldefense.com/v3/__https:/github.com/digitaltvguy__;!!PIZeeW5wscynRQ!tyDD7qbD21PEK7W8Fmszb6p46QwMgsSzOqppPMmVeWTY1OOmJWFIOsVMwFYbRHGQYfDtnOQGQWIJfzvGfxoPgXnnIQ$>?” *************** How can I help?

…

-Chris (digitaltvguy) From: John Bowler ***@***.***> Date: Friday, December 22, 2023 at 7:13 PM To: glennrp/libpng ***@***.***> Cc: Seeger, Chris (NBCUniversal) ***@***.***>, Author ***@***.***> Subject: [EXTERNAL] Re: [glennrp/libpng] Implement CICP Chunk described in PNG 3rd Edition (Priority 1) (Issue #508) Spamming the issues list seems inappropriate. — Reply to this email directly, view it on GitHub<https://urldefense.com/v3/__https:/github.com/glennrp/libpng/issues/508*issuecomment-1868144939__;Iw!!PIZeeW5wscynRQ!vRjPoeJ1qQsVwIKgogIH8U4J2y2ScXD8LUJpyHkAB4viFG_Qteg-f-VYjRF52gMQll9fslmocghOLifNYZxd_Rra2w$>, or unsubscribe<https://urldefense.com/v3/__https:/github.com/notifications/unsubscribe-auth/AANIO6HQBE5ETROJBJIXTLLYKYOZHAVCNFSM6AAAAABBAMB7NKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNRYGE2DIOJTHE__;!!PIZeeW5wscynRQ!vRjPoeJ1qQsVwIKgogIH8U4J2y2ScXD8LUJpyHkAB4viFG_Qteg-f-VYjRF52gMQll9fslmocghOLifNYZwATeWMJQ$>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[jbowler]

How can I help?

Do what I suggested to Chris Blume (@programmax) - submit a pull request.

[digitaltvguy]

We’re looking for help from your community and those who are familiar with the current implementation in libpng. Get Outlook for iOS<https://aka.ms/o0ukef>

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________________________________ From: John Bowler ***@***.***> Sent: Friday, December 22, 2023 7:30:39 PM To: glennrp/libpng ***@***.***> Cc: Seeger, Chris (NBCUniversal) ***@***.***>; Mention ***@***.***> Subject: [EXTERNAL] Re: [glennrp/libpng] Implement CICP Chunk described in PNG 3rd Edition (Priority 1) (Issue #508) How can I help? Do what I suggested to Chris Blume ***@***.***)<https://urldefense.com/v3/__https://github.com/ProgramMax__;!!PIZeeW5wscynRQ!v0672Bf_jc4FIH279BydCr5mnfuLV3pqysVx2Jc5EFSIvwr6VXv5U_f4XKJWXGwDC2Gf_b2j28_GPnCI-8DeTpng8A$> - submit a pull request. — Reply to this email directly, view it on GitHub<https://urldefense.com/v3/__https://github.com/glennrp/libpng/issues/508*issuecomment-1868150476__;Iw!!PIZeeW5wscynRQ!v0672Bf_jc4FIH279BydCr5mnfuLV3pqysVx2Jc5EFSIvwr6VXv5U_f4XKJWXGwDC2Gf_b2j28_GPnCI-8B3yw8qwg$>, or unsubscribe<https://urldefense.com/v3/__https://github.com/notifications/unsubscribe-auth/AANIO6A4YR3C5JYFIT2NIG3YKYQ27AVCNFSM6AAAAABBAMB7NKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNRYGE2TANBXGY__;!!PIZeeW5wscynRQ!v0672Bf_jc4FIH279BydCr5mnfuLV3pqysVx2Jc5EFSIvwr6VXv5U_f4XKJWXGwDC2Gf_b2j28_GPnCI-8A8pNB-EA$>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[jbowler]

Well, ok. Don't respond from your inbox: go to github.com and enter responses there.

[digitaltvguy]

We're looking for help from this community in translating the functions of the cICP chunk described in PNG 3rd Edition to libping.

Here is the temporary location for our conformance files with the new chunks:

https://www.dropbox.com/scl/fo/a44vfxw3p21kvkh8nywpc/h?rlkey=v63ekq5y49kd4omg59ng9q3zr&dl=0

Here is PNG 3rd Edition: https://www.w3.org/TR/png-3/

[jbowler]

I'll say it exactly this once more.

There is real work to be done here. You; you personally, need to do it. There's no one else here.

[svgeesus]

See #565

[jbowler]

Exactly, and @LucasChollet stepped up. Even better his pull request demonstrates an ability to deal with the actual build process and an understanding of the basic architecture. His patch was as good as one I might have contributed in another world and, perhaps, better because I'm sure he is approaching it with a less jaundiced mind. To be clear; he did the things I would have done well just as well and the errors he made were certainly those I might have made (though we would probably have made different errors in practice of course.)

I suggest to @LucasChollet and @ctruta that you talk directly to each other about what you are each trying to achieve. I suggest not on 565. I suggest to @ctruta that you need someone else on this and that someone is not me.