Jzazbz and JzCzhz reference ranges are too large.

[svgeesus]

Jzazbz is supposed to accommodate the BT.2020 color gamut within an az, bz range of ±0.5 (like ICtCp does). However, the Sadfar paper, figure 3, clearly shows a substantially smaller range should be used.

The green corner color(rec2020 0 1 0) converts to color(jzazbz 0.16058 -0.20664 0.14618), the blue corner color(rec2020 0 0 1) to color(jzazbz 0.09179 -0.07752 -0.20469) and a reddish magenta, which looks to be the greatest extent in the positive az direction, color(rec2020 1 0 0.7) is color(jzazbz 0.16455 0.17557 -0.01852).

An az, bz range of ±0.21 looks enough here.

For JzCzhz the peak chroma is color(rec2020 0 1 0) which is color(jzczhz 0.16058 0.25312 144.72). So a chroma range of 0 to 0.26 looks ample.

[svgeesus]

Related:

• jz**** color spaces have NaN where all other spaces have numbers #613