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lavu: Adding ARIB STD-B67 (hybrid log-gamma) enum value and transfer function.

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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>
This commit is contained in:
Neil Birkbeck
2016-04-21 12:00:05 -07:00
committed by Michael Niedermayer
parent 4c7d3e827c
commit 785038c92c
4 changed files with 37 additions and 0 deletions
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16
libavutil/color_utils.c
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@@ -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: