mh_PLAYer - ACES Sanity Kit
===========================
Kit v1.0  |  targets mh_PLAYer v2.12.0  |  2026-06-04
(c) 2026 Martin P. Heigan / mh_vfx_tools - anti-matter-3d.com
Licence: see "Licence & credits" at the end (mixed)

Purpose
-------
Known-good scene-linear test material for checking mh_PLAYer's ACES handling -
both the built-in ACES Filmic display mode and the accurate OCIO ACES pipeline.

Files
-----
  mh_aces_test_chart.exr        Scene-linear float EXR (linear Rec.709 primaries),
                                1920x1080. Contents:
                                  - top: 13-step EV ramp, -6..+6 stops of 18% grey
                                    (so it runs from ~0.003 up to ~11.5 = HDR)
                                  - neutral patches 0.0 / 0.045 / 0.09 / 0.18 /
                                    0.36 / 0.72 / 0.9 / 1.0
                                  - colour primaries at diffuse 0.18 and at 1.0
                                  - bottom: a 0 -> 4.0 linear highlight gradient
  mh_aces_test_chart_srgb.png   Plain sRGB render of the same chart (clamped) for
                                a quick non-EXR reference. This is NOT ACES.
  aces_cg_config.ocio           Official ACES 2.0 OCIO config (OCIO 2.5
                                "cg-config-latest", serialised to a standalone file -
                                no external LUTs). Validated with PyOpenColorIO.

Test A - built-in ACES Filmic (quick)
-------------------------------------
1. Open mh_aces_test_chart.exr.
2. Display Transform > ACES Filmic (Narkowicz 2016).  EV = 0.
3. Compare against Display Transform > sRGB:
   - In sRGB the top EV ramp and the 0->4 gradient clip hard to white past 1.0.
   - In ACES Filmic the highlights roll off smoothly instead of clipping.
   This mode is a fast approximation - good for a look, not for matching a facility.

Test B - OCIO ACES 2.0 (accurate)
---------------------------------
1. Open mh_aces_test_chart.exr.
2. Colour Management > Browse Config... > aces_cg_config.ocio.
3. Set the combos (the chart is linear Rec.709):
       Input CS : Linear Rec.709 (sRGB)
       Display  : sRGB - Display
       View     : ACES 2.0 - SDR 100 nits (Rec.709)
   then click Apply.
4. The dropdowns are populated from the config; other useful views are
   "Un-tone-mapped", "Video (colorimetric)", and "Raw".

Reference values (neutral 18% grey patch)
------------------------------------------
  OCIO ACES 2.0 SDR view ...... ~0.349  (~89 / 255)   <- the ACES tone curve
  plain sRGB (Test A sRGB mode)  ~0.461  (~118 / 255)  <- sRGB OETF of 0.18
  built-in ACES Filmic ........ differs (Narkowicz approximation)

What to look for
----------------
  - Highlight roll-off: the 0->4 gradient and the +stops of the EV ramp should
    compress gracefully under ACES, vs clip to white under sRGB/Linear.
  - 18% grey reads as a mid neutral (values above); primaries keep believable hue.

CLI (headless)
--------------
  Built-in ACES:  mh_player mh_aces_test_chart.exr -m aces -p
  Bake ACES:      mh_player -X mh_aces_test_chart.exr out.png -m aces
  OCIO ACES:      mh_player -X mh_aces_test_chart.exr out.png -m ocio ^
                    --ocio-config aces_cg_config.ocio ^
                    --ocio-src "Linear Rec.709 (sRGB)" ^
                    --ocio-display "sRGB - Display" ^
                    --ocio-view "ACES 2.0 - SDR 100 nits (Rec.709)"

Note
----
The EXR is scene-linear with linear Rec.709 / sRGB primaries, which is why the
OCIO Input CS is "Linear Rec.709 (sRGB)". If you load it and it looks washed out
in plain sRGB mode, that is expected - it is linear data awaiting a transform.

Licence & credits
-----------------
Kit (c) 2026 Martin P. Heigan / mh_vfx_tools, anti-matter-3d.com.
The kit packaging, the test chart (EXR + PNG) and this document are released
under Creative Commons BY-NC-ND 4.0
(https://creativecommons.org/licenses/by-nc-nd/4.0/).

aces_cg_config.ocio is the ACES reference "CG config" (cg-config-latest),
generated with OpenColorIO 2.5. It is published by the Academy Software
Foundation / ACES and licensed under Apache-2.0; it is included here as a
convenience and is NOT covered by the CC licence above. Source:
https://github.com/AcademySoftwareFoundation/OpenColorIO-Config-ACES
ACES is a trademark of the Academy of Motion Picture Arts and Sciences. This
kit is independent and not endorsed by the Academy or the ASWF.
