4th edition meta-issue

[ProgramMax]

This is a meta-issue, tracking the various individual issues for 4th edition.
In general, discussion should happen on those issues, not here.
We will update this post to reflect the current status of 4th edition issues.

• gain maps
  Proposal: gain maps for PNG #380
  ISO 21496-1 is not yet free. Liaison established (see Liaison letter from ISO TC 42/WG 23 on Gain Maps #366 ).
• gain curves
  Some tone mapping requires the average luminance between frames #311
  SMPTE ST 2094-50 is not yet free. However, we'll probably wait for AOM's version anyway.
• T.35 metadata
  T.35 is freely available. This is tied to gain curves, so it is also waiting.
• Tone mapping general issues
  Some tone mapping requires the average luminance between frames #311
  Tone-mapping should be stable when mDCv and cLLi are static #319
• HDR Reference White Level
  Add PNG hRWl (HDR Reference White Level) chunk to conform to ISO 22028-5 #390
  ISO/TS 22028-5 is not freely available. Liaison work is being done here, too.
  ITU-R BT.2408 is technically aligned with ISO 22028-5, and freely available
• Negative cHRM values
• C2PA metadata
  C2PA and PNG #542
• Cleanup
  Filtering description confussion #543
  Improve section 7.2 Scanlines #552
  Unclear tIME restrictions #572

[Crissov]

Is the plan then to attach all open issues that are currently labeled as enhancement to this or #537 – or close them as won't do?

[ProgramMax]

Is the plan then to attach all open issues that are currently labeled as enhancement to this or #537 – or close them as won't do?

No. Some issues were created as generally good or interesting ideas, but do not have industry pressure or demand, for example. Those types of issues are not scheduled. However, closing them isn't the best option, either.

They are instead given the "Future edition considerations" milestone. But they will not show up in the 4th or 5th edition meta-issues unless they get scheduled.