diff options
| author | Neil Birkbeck <neil.birkbeck@gmail.com> | 2016-04-21 22:00:05 +0300 |
|---|---|---|
| committer | Michael Niedermayer <michael@niedermayer.cc> | 2016-06-01 17:32:08 +0300 |
| commit | 785038c92cc7fc1da437576382083246ca598fce (patch) | |
| tree | 464eb45e093a254d3dc3d8ac654bbdca3812b9a8 /libavutil/color_utils.c | |
| parent | 4c7d3e827c80627e4c77b01cc9478f4603a59b90 (diff) | |
lavu: Adding ARIB STD-B67 (hybrid log-gamma) enum value and transfer function.
Adding hybrid log-gamma (https://en.wikipedia.org/wiki/Hybrid_Log-Gamma)
based on the standardization in ARIB STD-B67:
http://www.arib.or.jp/english/html/overview/doc/2-STD-B67v1_0.pdf
The choice of enum value of 18 is consistent with HEVC:
http://phenix.it-sudparis.eu/jct/doc_end_user/current_document.php?id=10481
And also with latest proposal for color format in mkv:
https://mailarchive.ietf.org/arch/search/?email_list=cellar&gbt=1&q=Colour+Format+proposal
The implementation assumes a nominal input range of [0, 1], which is
consistent with HEVC.
Signed-off-by: Neil Birkbeck <neil.birkbeck@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Diffstat (limited to 'libavutil/color_utils.c')
| -rw-r--r-- | libavutil/color_utils.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/libavutil/color_utils.c b/libavutil/color_utils.c index 63f2230980..eb8bc7b5fc 100644 --- a/libavutil/color_utils.c +++ b/libavutil/color_utils.c @@ -155,6 +155,18 @@ static double avpriv_trc_smpte_st428_1(double Lc) : pow(48.0 * Lc / 52.37, 1.0 / 2.6); } + +static double avpriv_trc_arib_std_b67(double Lc) { + // The function uses the definition from HEVC, which assumes that the peak + // white is input level = 1. (this is equivalent to scaling E = Lc * 12 and + // using the definition from the ARIB STD-B67 spec) + const double a = 0.17883277; + const double b = 0.28466892; + const double c = 0.55991073; + return (0.0 > Lc) ? 0.0 : + (Lc <= 1.0 / 12.0 ? sqrt(3.0 * Lc) : a * log(12.0 * Lc - b) + c); +} + avpriv_trc_function avpriv_get_trc_function_from_trc(enum AVColorTransferCharacteristic trc) { avpriv_trc_function func = NULL; @@ -209,6 +221,10 @@ avpriv_trc_function avpriv_get_trc_function_from_trc(enum AVColorTransferCharact func = avpriv_trc_smpte_st428_1; break; + case AVCOL_TRC_ARIB_STD_B67: + func = avpriv_trc_arib_std_b67; + break; + case AVCOL_TRC_RESERVED0: case AVCOL_TRC_UNSPECIFIED: case AVCOL_TRC_RESERVED: |