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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>
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
View File

@ -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:

1
libavutil/pixdesc.c
View File

@ -2080,6 +2080,7 @@ static const char *color_transfer_names[AVCOL_TRC_NB] = {
"bt470bg", "smpte170m", "smpte240m", "linear", "log100",
"log316", "iec61966-2-4", "bt1361e", "iec61966-2-1",
"bt2020-10", "bt2020-20", "smpte2084", "smpte428-1",
"arib-std-b67"
};
static const char *color_space_names[AVCOL_SPC_NB] = {

1
libavutil/pixfmt.h
View File

@ -420,6 +420,7 @@ enum AVColorTransferCharacteristic {
AVCOL_TRC_BT2020_12 = 15, ///< ITU-R BT2020 for 12 bit system
AVCOL_TRC_SMPTEST2084 = 16, ///< SMPTE ST 2084 for 10, 12, 14 and 16 bit systems
AVCOL_TRC_SMPTEST428_1 = 17, ///< SMPTE ST 428-1
AVCOL_TRC_ARIB_STD_B67 = 18, ///< ARIB STD-B67, known as "Hybrid log-gamma"
AVCOL_TRC_NB, ///< Not part of ABI
};

19
tests/ref/fate/color_utils
View File

@ -283,3 +283,22 @@ AVColorTransferCharacteristic=17 calling func(15123.456700) expected=39.174525
AVColorTransferCharacteristic=17 calling func(19845.889230) expected=43.490646
AVColorTransferCharacteristic=17 calling func(98678.423100) expected=80.593559
AVColorTransferCharacteristic=17 calling func(99999.899998) expected=81.006971
AVColorTransferCharacteristic=18 calling func(-0.100000) expected=0.000000
AVColorTransferCharacteristic=18 calling func(-0.018054) expected=0.000000
AVColorTransferCharacteristic=18 calling func(-0.010000) expected=0.000000
AVColorTransferCharacteristic=18 calling func(-0.004490) expected=0.000000
AVColorTransferCharacteristic=18 calling func(0.000000) expected=0.000000
AVColorTransferCharacteristic=18 calling func(0.003162) expected=0.097400
AVColorTransferCharacteristic=18 calling func(0.005000) expected=0.122474
AVColorTransferCharacteristic=18 calling func(0.009000) expected=0.164317
AVColorTransferCharacteristic=18 calling func(0.015000) expected=0.212132
AVColorTransferCharacteristic=18 calling func(0.100000) expected=0.544089
AVColorTransferCharacteristic=18 calling func(1.000000) expected=1.000000
AVColorTransferCharacteristic=18 calling func(52.370000) expected=1.712092
AVColorTransferCharacteristic=18 calling func(125.098765) expected=1.867862
AVColorTransferCharacteristic=18 calling func(1999.111230) expected=2.363502
AVColorTransferCharacteristic=18 calling func(6945.443000) expected=2.586219
AVColorTransferCharacteristic=18 calling func(15123.456700) expected=2.725380
AVColorTransferCharacteristic=18 calling func(19845.889230) expected=2.773978
AVColorTransferCharacteristic=18 calling func(98678.423100) expected=3.060803
AVColorTransferCharacteristic=18 calling func(99999.899998) expected=3.063182