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

> On Dec 9, 2023, at 21:05, Seeger, Chris (NBCUniversal) <Chris.Seeger@nbcuni.com> wrote:
> 
> Thanks Leo!
> 
> It seems like Preview in MacOS is not reading the cicp chunk.  Can you help us fix it?

There are actually two levels of support that are relevant here:
1. Supporting the HDR metadata (i.e. CICP)
2. Displaying HDR content as HDR rather than tone-mapping to SDR

If you don't support #1, things will simply display very incorrectly and I think pretty much everything that uses the OS-level image processing APIs will correctly handle #1. But HDR content may still get displayed as (correctly tone-mapped according to the ITU doc that I can't remember the number of) SDR even if the OS supports HDR content. The reason is that just blindly enabling HDR in an app may mess up a UI that is not prepared for parts of it to "pop". I think these are the Apple sessions that discuss it IIRC:

https://developer.apple.com/videos/play/wwdc2023/10181/
https://developer.apple.com/documentation/uikit/images_and_pdf/supporting_hdr_images_in_your_app?language=objc

So not all apps on iOS/macOS will actually display content as HDR. But they should all be handling it according to the spec recommendations.

Cheers,
//Leo

> 
> Get Outlook for iOS <https://aka.ms/o0ukef>
> From: Leo Barnes <lbarnes@apple.com>
> Sent: Saturday, December 9, 2023 1:55:15 PM
> To: Chris Blume (ProgramMax) <programmax@gmail.com>
> Cc: Seeger, Chris (NBCUniversal) <Chris.Seeger@nbcuni.com>; public-png@w3.org <public-png@w3.org>
> Subject: Re: [EXTERNAL] Conformance files in PQ, HLG, SDR-BT.709?
>  
> 
> 
>> On Dec 9, 2023, at 04:13, Chris Blume (ProgramMax) <programmax@gmail.com> wrote:
>> 
>> My understanding (could be wrong) is that a lot of image handling (only PNG?) on Apple platforms happens via OS-provided APIs.
> 
> Yes, this is correct. Unless apps have very specific needs they tend to use ImageIO <https://urldefense.com/v3/__https://developer.apple.com/documentation/imageio?language=objc__;!!PIZeeW5wscynRQ!vur_aJ2XTckLKYECOxw6G7JKAv3gyncliPaPK9vGMFJ-PAi3RpaWBa_gHDzyNeSTBGF1z95EWs1Ek7d6$> to parse, decode and encode images. It supports a bunch of image formats (including PNG, JPEG and HEIF) in a format agnostic API.
> If ImageIO adds support for a new format or a new feature of an existing format, that tends to then come for free for all apps on all Apple platforms.
> 
>> For example, if we're concerned about Safari's support of PNG, we actually care about MacOS's / iOS's support.
> 
> Yes and no. Safari also tends to backport some things for new versions of Safari on older OS releases.
> 
> Cheers,
> //Leo
> 
>> 
>> On Fri, Dec 8, 2023 at 6:59 PM Seeger, Chris (NBCUniversal) <Chris.Seeger@nbcuni.com <mailto:Chris.Seeger@nbcuni.com>> wrote:
>> It appears to be MacOS system wide.  The Photo’s app also reads the CICP chunk.
>> 
>>  
>> 
>> From: Chris Lilley <chris@w3.org <mailto:chris@w3.org>>
>> Date: Friday, December 8, 2023 at 4:55 PM
>> To: Seeger, Chris (NBCUniversal) <Chris.Seeger@nbcuni.com <mailto:Chris.Seeger@nbcuni.com>>, 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?
>> 
>> Great, so we can make a reftest which fails if the narrow/full flag is 
>> ignored, put that in web platform tests and file bugs on those 
>> implementations to fix the bug.
>> 
>> On 2023-12-08 16:46, Seeger, Chris (NBCUniversal) wrote:
>> > 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 Lilley
>> @svgeesus
>> Technical Director @ W3C
>> W3C Strategy Team, Core Web Design
>> W3C Architecture & Technology Team, Core Web & Media
>> 
>> 
>