Commit bac90482 authored by Kevin Wheatley's avatar Kevin Wheatley Committed by Michael Niedermayer

avutil/color_utils: Add basic transfer functions for each AVColorTransferCharacteristic

Most functions are valid over a domain and range of [0.0-1.0] but
some are defined over greater. This patch does not deal with
AVColorRange and assumes AVCOL_RANGE_JPEG for the returned values.
Signed-off-by: 's avatarKevin Wheatley <kevin.j.wheatley@gmail.com>
parent f6e598af
......@@ -18,6 +18,9 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stddef.h>
#include <math.h>
#include "libavutil/color_utils.h"
#include "libavutil/pixfmt.h"
......@@ -50,3 +53,166 @@ double avpriv_get_gamma_from_trc(enum AVColorTransferCharacteristic trc)
}
return gamma;
}
#define BT709_alpha 1.099296826809442
#define BT709_beta 0.018053968510807
static double avpriv_trc_bt709(double Lc)
{
const double a = BT709_alpha;
const double b = BT709_beta;
return (0.0 > Lc) ? 0.0
: ( b > Lc) ? 4.500 * Lc
: a * pow(Lc, 0.45) - (a - 1.0);
}
static double avpriv_trc_gamma22(double Lc)
{
return (0.0 > Lc) ? 0.0 : pow(Lc, 1.0/ 2.2);
}
static double avpriv_trc_gamma28(double Lc)
{
return (0.0 > Lc) ? 0.0 : pow(Lc, 1.0/ 2.8);
}
static double avpriv_trc_smpte240M(double Lc)
{
const double a = 1.1115;
const double b = 0.0228;
return (0.0 > Lc) ? 0.0
: ( b > Lc) ? 4.000 * Lc
: a * pow(Lc, 0.45) - (a - 1.0);
}
static double avpriv_trc_linear(double Lc)
{
return Lc;
}
static double avpriv_trc_log(double Lc)
{
return (0.01 > Lc) ? 0.0 : 1.0 + log10(Lc) / 2.0;
}
static double avpriv_trc_log_sqrt(double Lc)
{
// sqrt(10) / 1000
return (0.00316227766 > Lc) ? 0.0 : 1.0 + log10(Lc) / 2.5;
}
static double avpriv_trc_iec61966_2_4(double Lc)
{
const double a = BT709_alpha;
const double b = BT709_beta;
return (-b >= Lc) ? -a * pow(-Lc, 0.45) + (a - 1.0)
: ( b > Lc) ? 4.500 * Lc
: a * pow( Lc, 0.45) - (a - 1.0);
}
static double avpriv_trc_bt1361(double Lc)
{
const double a = BT709_alpha;
const double b = BT709_beta;
return (-0.0045 >= Lc) ? -(a * pow(-4.0 * Lc, 0.45) + (a - 1.0)) / 4.0
: ( b > Lc) ? 4.500 * Lc
: a * pow( Lc, 0.45) - (a - 1.0);
}
static double avpriv_trc_iec61966_2_1(double Lc)
{
const double a = 1.055;
const double b = 0.0031308;
return (0.0 > Lc) ? 0.0
: ( b > Lc) ? 12.92 * Lc
: a * pow(Lc, 1.0 / 2.4) - (a - 1.0);
}
static double avpriv_trc_smpte_st2084(double Lc)
{
const double c1 = 3424.0 / 4096.0; // c3-c2 + 1
const double c2 = 32.0 * 2413.0 / 4096.0;
const double c3 = 32.0 * 2392.0 / 4096.0;
const double m = 128.0 * 2523.0 / 4096.0;
const double n = 0.25 * 2610.0 / 4096.0;
const double L = Lc / 10000.0;
const double Ln = pow(L, n);
return (0.0 > Lc) ? 0.0
: pow((c1 + c2 * Ln) / (1.0 + c3 * Ln), m);
}
static double avpriv_trc_smpte_st428_1(double Lc)
{
return (0.0 > Lc) ? 0.0
: pow(48.0 * Lc / 52.37, 1.0 / 2.6);
}
avpriv_trc_function avpriv_get_trc_function_from_trc(enum AVColorTransferCharacteristic trc)
{
avpriv_trc_function func = NULL;
switch (trc) {
case AVCOL_TRC_BT709:
case AVCOL_TRC_SMPTE170M:
case AVCOL_TRC_BT2020_10:
case AVCOL_TRC_BT2020_12:
func = avpriv_trc_bt709;
break;
case AVCOL_TRC_GAMMA22:
func = avpriv_trc_gamma22;
break;
case AVCOL_TRC_GAMMA28:
func = avpriv_trc_gamma28;
break;
case AVCOL_TRC_SMPTE240M:
func = avpriv_trc_smpte240M;
break;
case AVCOL_TRC_LINEAR:
func = avpriv_trc_linear;
break;
case AVCOL_TRC_LOG:
func = avpriv_trc_log;
break;
case AVCOL_TRC_LOG_SQRT:
func = avpriv_trc_log_sqrt;
break;
case AVCOL_TRC_IEC61966_2_4:
func = avpriv_trc_iec61966_2_4;
break;
case AVCOL_TRC_BT1361_ECG:
func = avpriv_trc_bt1361;
break;
case AVCOL_TRC_IEC61966_2_1:
func = avpriv_trc_iec61966_2_1;
break;
case AVCOL_TRC_SMPTEST2084:
func = avpriv_trc_smpte_st2084;
break;
case AVCOL_TRC_SMPTEST428_1:
func = avpriv_trc_smpte_st428_1;
break;
case AVCOL_TRC_RESERVED0:
case AVCOL_TRC_UNSPECIFIED:
case AVCOL_TRC_RESERVED:
default:
break;
}
return func;
}
......@@ -36,4 +36,21 @@
*/
double avpriv_get_gamma_from_trc(enum AVColorTransferCharacteristic trc);
typedef double (*avpriv_trc_function)(double);
/**
* Determine the function needed to apply the given
* AVColorTransferCharacteristic to linear input.
*
* The function returned should expect a nominal domain and range of [0.0-1.0]
* values outside of this range maybe valid depending on the chosen
* characteristic function.
*
* @return Will return pointer to the function matching the
* supplied Transfer Characteristic. If unspecified will
* return NULL:
*/
avpriv_trc_function avpriv_get_trc_function_from_trc(enum AVColorTransferCharacteristic trc);
#endif
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