KoColorTransferFunctions.h File Reference

#include <cmath>
#include <QtGlobal>
#include <KoAlwaysInline.h>
#include <KoMultiArchBuildSupport.h>
#include <KoStreamedMath.h>

Go to the source code of this file.

Classes
struct	KoColorTransferFunctions< Arch >

Enumerations
enum class	ConversionPolicy { KeepTheSame , ApplyPQ , ApplyHLG , ApplySMPTE428 }
enum class	LinearizePolicy { KeepTheSame , LinearFromPQ , LinearFromHLG , LinearFromSMPTE428 }
	The KoColorTransferFunctions class. More...

Functions
ALWAYS_INLINE float	applyHLGCurve (float x) noexcept
ALWAYS_INLINE void	applyHLGOOTF (float *rgb, const double *lumaCoefficients, float gamma=1.2f, float nominalPeak=1000.0f) noexcept
ALWAYS_INLINE float	applySmpte2048Curve (float x) noexcept
ALWAYS_INLINE float	applySMPTE_ST_428Curve (float x) noexcept
ALWAYS_INLINE float	HLGOOTFGamma (float nominalPeak) noexcept
ALWAYS_INLINE float	removeHLGCurve (float x) noexcept
ALWAYS_INLINE void	removeHLGOOTF (float *rgb, const double *lumaCoefficients, float gamma=1.2f, float nominalPeak=1000.0f) noexcept
ALWAYS_INLINE float	removeSmpte2048Curve (float x) noexcept
ALWAYS_INLINE float	removeSMPTE_ST_428Curve (float x) noexcept

Variables
static constexpr uint16_t	max12bit = 4095.f
static constexpr float	max16bit = 65535.0f
static constexpr float	multiplier10bit = 1.0f / 1023.0f
static constexpr float	multiplier12bit = 1.0f / 4095.0f
static constexpr float	multiplier16bit = 1.0f / max16bit

Enumeration Type Documentation

ConversionPolicy

enum class ConversionPolicy

strong

Enumerator
KeepTheSame
ApplyPQ
ApplyHLG
ApplySMPTE428

Definition at line 36 of file KoColorTransferFunctions.h.

{ KeepTheSame, ApplyPQ, ApplyHLG, ApplySMPTE428 };

LinearizePolicy

enum class LinearizePolicy

strong

The KoColorTransferFunctions class.

A number of often used transferFunctions.

These functions can, at the time of writing, not be implemented in ICC profiles, so instead, we apply or remove the curve as necessary.

Enumerator
KeepTheSame
LinearFromPQ
LinearFromHLG
LinearFromSMPTE428

Definition at line 28 of file KoColorTransferFunctions.h.

{ KeepTheSame, LinearFromPQ, LinearFromHLG, LinearFromSMPTE428 };

Function Documentation

applyHLGCurve()

ALWAYS_INLINE float applyHLGCurve ( float x )

noexcept

Definition at line 106 of file KoColorTransferFunctions.h.

{
    const float a = 0.17883277f;
    const float b = 0.28466892f;
    const float c = 0.55991073f;
 
    if (x > 1.0f / 12.0f) {
        return (a * logf(12.0f * x - b) + c);
    } else {
        // return (sqrt(3.0) * powf(x, 0.5));
        return (sqrtf(3.0f) * sqrtf(x));
    }
}

applyHLGOOTF()

ALWAYS_INLINE void applyHLGOOTF ( float * rgb, const double * lumaCoefficients, float gamma = 1.2f, float nominalPeak = 1000.0f )

noexcept

Definition at line 75 of file KoColorTransferFunctions.h.

{
    const float luma = (rgb[0] * static_cast<float>(lumaCoefficients[0]))
        + (rgb[1] * static_cast<float>(lumaCoefficients[1]))
        + (rgb[2] * static_cast<float>(lumaCoefficients[2]));
    const float a = nominalPeak * powf(luma, gamma - 1.f);
    rgb[0] *= a;
    rgb[1] *= a;
    rgb[2] *= a;
}

applySmpte2048Curve()

ALWAYS_INLINE float applySmpte2048Curve ( float x )

noexcept

Definition at line 38 of file KoColorTransferFunctions.h.

{
    const float m1 = 2610.0f / 4096.0f / 4.0f;
    const float m2 = 2523.0f / 4096.0f * 128.0f;
    const float a1 = 3424.0f / 4096.0f;
    const float c2 = 2413.0f / 4096.0f * 32.0f;
    const float c3 = 2392.0f / 4096.0f * 32.0f;
    const float a4 = 1.0f;
    const float x_p = powf(0.008f * std::max(0.0f, x), m1);
    const float res = powf((a1 + c2 * x_p) / (a4 + c3 * x_p), m2);
    return res;
}

applySMPTE_ST_428Curve()

ALWAYS_INLINE float applySMPTE_ST_428Curve ( float x )

noexcept

Definition at line 133 of file KoColorTransferFunctions.h.

{
    return powf(48.0f * x * (1.f / 52.37f), (1.f / 2.6f));
}

HLGOOTFGamma()

ALWAYS_INLINE float HLGOOTFGamma ( float nominalPeak )

noexcept

Definition at line 66 of file KoColorTransferFunctions.h.

{
    const float k = 1.111f;
    return 1.2f * powf(k, log2f(nominalPeak * (1.f / 1000.0f)));
}

removeHLGCurve()

ALWAYS_INLINE float removeHLGCurve ( float x )

noexcept

Definition at line 120 of file KoColorTransferFunctions.h.

{
    const float a = 0.17883277f;
    const float b = 0.28466892f;
    const float c = 0.55991073f;
    if (x <= 0.5f) {
        // return (powf(x, 2.0) / 3.0);
        return x * x * (1.f / 3.0f);
    } else {
        return (expf((x - c) * (1.f / a)) + b) * (1.f / 12.0f);
    }
}

removeHLGOOTF()

ALWAYS_INLINE void removeHLGOOTF ( float * rgb, const double * lumaCoefficients, float gamma = 1.2f, float nominalPeak = 1000.0f )

noexcept

Definition at line 92 of file KoColorTransferFunctions.h.

{
    const float luma = (rgb[0] * static_cast<float>(lumaCoefficients[0]))
        + (rgb[1] * static_cast<float>(lumaCoefficients[1]))
        + (rgb[2] * static_cast<float>(lumaCoefficients[2]));
    const float multiplier = powf(luma * (1.f / nominalPeak), (1.f - gamma) * (1.f / gamma)) * (1.f / nominalPeak);
    rgb[0] *= multiplier;
    rgb[1] *= multiplier;
    rgb[2] *= multiplier;
}

removeSmpte2048Curve()

ALWAYS_INLINE float removeSmpte2048Curve ( float x )

noexcept

Definition at line 51 of file KoColorTransferFunctions.h.

{
    const float m1_r = 4096.0f * 4.0f / 2610.0f;
    const float m2_r = 4096.0f / 2523.0f / 128.0f;
    const float a1 = 3424.0f / 4096.0f;
    const float c2 = 2413.0f / 4096.0f * 32.0f;
    const float c3 = 2392.0f / 4096.0f * 32.0f;
 
    const float x_p = powf(x, m2_r);
    const float res = powf(qMax(0.0f, x_p - a1) / (c2 - c3 * x_p), m1_r);
    return res * 125.0f;
}

removeSMPTE_ST_428Curve()

ALWAYS_INLINE float removeSMPTE_ST_428Curve ( float x )

noexcept

Definition at line 138 of file KoColorTransferFunctions.h.

{
    return (52.37f / 48.0f) * powf(x, 2.6f);
}

Variable Documentation

max12bit

constexpr uint16_t max12bit = 4095.f

staticconstexpr

Definition at line 30 of file KoColorTransferFunctions.h.

max16bit

constexpr float max16bit = 65535.0f

staticconstexpr

Definition at line 31 of file KoColorTransferFunctions.h.

multiplier10bit

constexpr float multiplier10bit = 1.0f / 1023.0f

staticconstexpr

Definition at line 32 of file KoColorTransferFunctions.h.

multiplier12bit

constexpr float multiplier12bit = 1.0f / 4095.0f

staticconstexpr

Definition at line 33 of file KoColorTransferFunctions.h.

multiplier16bit

constexpr float multiplier16bit = 1.0f / max16bit

staticconstexpr

Definition at line 34 of file KoColorTransferFunctions.h.