diff --git a/staging/color-management/appendix.md b/staging/color-management/appendix.md index 8bd6141..bdac16e 100644 --- a/staging/color-management/appendix.md +++ b/staging/color-management/appendix.md @@ -53,6 +53,22 @@ The above are specified by [ITU-R BT.1886]. Note, that $`E < 0`$ and $`E > 1`$ are possible with limited range quantization, as required by e.g. the calibration method in [ITU-R BT.814]. +### `compound_power_2_4` + +```math +O = \begin{cases} +\frac{E}{12.92}, & 0 \leq E < 0.04045\\ +\left( \frac{E + 0.055}{1.055} \right)^{2.4}, & 0.04045 \leq E \leq 1 +\end{cases} +``` + +The above is the IEC 61966-2-1 piece-wise transfer function, +as recorded in [Khronos Data Format Specification][KDFS] 1.4.0 +Section 13.3, and restricted to the unit range. + +```math +L = (L_W - L_B)O + L_B +``` ### `gamma22` @@ -125,3 +141,4 @@ L = 10'000\ \mathrm{cd/m²} \cdot O + L_B [ITU-R BT.814]: https://gitlab.freedesktop.org/pq/color-and-hdr/-/blob/main/doc/specs.md#itu-r-bt814 [ITU-R BT.1886]: https://gitlab.freedesktop.org/pq/color-and-hdr/-/blob/main/doc/specs.md#itu-r-bt1886 [ITU-R BT.2100]: https://gitlab.freedesktop.org/pq/color-and-hdr/-/blob/main/doc/specs.md#itu-r-bt2100 +[KDFS]: https://registry.khronos.org/DataFormat/ diff --git a/staging/color-management/color-management-v1.xml b/staging/color-management/color-management-v1.xml index 2eb4722..5dc8591 100644 --- a/staging/color-management/color-management-v1.xml +++ b/staging/color-management/color-management-v1.xml @@ -288,8 +288,7 @@ - United States Federal Communications Commission (2003) Title 47 Code of Federal Regulations 73.682 (a) (20) - Rec. ITU-R BT.1700-0 625 PAL and 625 SECAM - - Note: an sRGB display (IEC 61966-2-1) uses this transfer function. + - IEC 61966-2-1 (reference display) @@ -326,18 +325,18 @@ - IEC 61966-2-4 - - + + Transfer characteristics as defined by - IEC 61966-2-1 sRGB - Note: This is not appropriate for describing sRGB material. - sRGB material is intended to be viewed on an sRGB display, and - that is described by gamma22. + As a rule of thumb, use gamma22 for video, motion picture and + computer graphics, or compound_power_2_4 for ICC calibrated print + workflows. - - + + Transfer characteristics as defined by - IEC 61966-2-1 sYCC @@ -387,6 +386,12 @@ ARIB STD-B67 or BT.2100. + + + Encoding characteristics as defined by IEC 61966-2-1, for displays + that invert the encoding function. + +