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filmicrgb: add rational function to toe/shoulder #8764

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Apr 24, 2021
Merged

filmicrgb: add rational function to toe/shoulder #8764

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113 changes: 91 additions & 22 deletions data/kernels/filmic.cl
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,13 @@ typedef enum dt_iop_filmicrgb_reconstruction_type_t
DT_FILMIC_RECONSTRUCT_RATIOS = 1,
} dt_iop_filmicrgb_reconstruction_type_t;

typedef enum dt_iop_filmicrgb_curve_type_t
{
DT_FILMIC_CURVE_POLY_4 = 0, // $DESCRIPTION: "hard"
DT_FILMIC_CURVE_POLY_3 = 1, // $DESCRIPTION: "soft"
DT_FILMIC_CURVE_RATIONAL = 2, // $DESCRIPTION: "safe"
} dt_iop_filmicrgb_curve_type_t;

kernel void
filmic (read_only image2d_t in, write_only image2d_t out, int width, int height,
const float dynamic_range, const float shadows_range, const float grey,
Expand Down Expand Up @@ -218,14 +225,66 @@ inline float4 linear_saturation(const float4 x, const float luminance, const flo

inline float filmic_spline(const float x,
const float4 M1, const float4 M2, const float4 M3, const float4 M4, const float4 M5,
const float latitude_min, const float latitude_max)
const float latitude_min, const float latitude_max,
const dt_iop_filmicrgb_curve_type_t type[2])
{
// if type polynomial :
// y = M5 * x⁴ + M4 * x³ + M3 * x² + M2 * x¹ + M1 * x⁰
// but we rewrite it using Horner factorisation, to spare ops and enable FMA in available
// else if type rational :
// y = M1 * (M2 * (x - x_0)² + (x - x_0)) / (M2 * (x - x_0)² + (x - x_0) + M3)

return (x < latitude_min) ? M1.x + x * (M2.x + x * (M3.x + x * (M4.x + x * M5.x))) : // toe
(x > latitude_max) ? M1.y + x * (M2.y + x * (M3.y + x * (M4.y + x * M5.y))) : // shoulder
M1.z + x * (M2.z + x * (M3.z + x * (M4.z + x * M5.z))); // latitude
float result;

if(x < latitude_min)
{
// toe
if(type[0] == DT_FILMIC_CURVE_POLY_4)
{
// polynomial toe, 4th order
result = M1.x + x * (M2.x + x * (M3.x + x * (M4.x + x * M5.x)));
}
else if(type[0] == DT_FILMIC_CURVE_POLY_3)
{
// polynomial toe, 3rd order
result = M1.x + x * (M2.x + x * (M3.x + x * M4.x));
}
else
{
// rational toe
const float xi = latitude_min - x;
const float rat = xi * (xi * M2.x + 1.f);
result = M4.x - M1.x * rat / (rat + M3.x);
}
}
else if(x > latitude_max)
{
// shoulder
if(type[1] == DT_FILMIC_CURVE_POLY_4)
{
// polynomial shoulder, 4th order
result = M1.y + x * (M2.y + x * (M3.y + x * (M4.y + x * M5.y)));
}
else if(type[1] == DT_FILMIC_CURVE_POLY_3)
{
// polynomial shoulder, 3rd order
result = M1.y + x * (M2.y + x * (M3.y + x * M4.y));
}
else
{
// rational toe
const float xi = x - latitude_max;
const float rat = xi * (xi * M2.y + 1.f);
result = M4.y + M1.y * rat / (rat + M3.y);
}
}
else
{
// latitude
result = M1.z + x * M2.z;
}

return result;
}

#define NORM_MIN 1.52587890625e-05f // norm can't be < to 2^(-16)
Expand All @@ -252,7 +311,8 @@ inline float4 filmic_split_v1(const float4 i,
read_only image2d_t lut, const int use_work_profile,
const float sigma_toe, const float sigma_shoulder, const float saturation,
const float4 M1, const float4 M2, const float4 M3, const float4 M4, const float4 M5,
const float latitude_min, const float latitude_max, const float output_power)
const float latitude_min, const float latitude_max, const float output_power,
const dt_iop_filmicrgb_curve_type_t type[2])
{
float4 o;

Expand All @@ -272,9 +332,9 @@ inline float4 filmic_split_v1(const float4 i,
o = linear_saturation(o, luminance, desaturation);

// Filmic spline
o.x = filmic_spline(o.x, M1, M2, M3, M4, M5, latitude_min, latitude_max);
o.y = filmic_spline(o.y, M1, M2, M3, M4, M5, latitude_min, latitude_max);
o.z = filmic_spline(o.z, M1, M2, M3, M4, M5, latitude_min, latitude_max);
o.x = filmic_spline(o.x, M1, M2, M3, M4, M5, latitude_min, latitude_max, type);
o.y = filmic_spline(o.y, M1, M2, M3, M4, M5, latitude_min, latitude_max, type);
o.z = filmic_spline(o.z, M1, M2, M3, M4, M5, latitude_min, latitude_max, type);

// Output power
o = native_powr(clamp(o, (float4)0.0f, (float4)1.0f), output_power);
Expand All @@ -288,7 +348,8 @@ inline float4 filmic_split_v2_v3(const float4 i,
read_only image2d_t lut, const int use_work_profile,
const float sigma_toe, const float sigma_shoulder, const float saturation,
const float4 M1, const float4 M2, const float4 M3, const float4 M4, const float4 M5,
const float latitude_min, const float latitude_max, const float output_power)
const float latitude_min, const float latitude_max, const float output_power,
const dt_iop_filmicrgb_curve_type_t type[2])
{
float4 o;

Expand All @@ -308,9 +369,9 @@ inline float4 filmic_split_v2_v3(const float4 i,
o = linear_saturation(o, luminance, desaturation);

// Filmic spline
o.x = filmic_spline(o.x, M1, M2, M3, M4, M5, latitude_min, latitude_max);
o.y = filmic_spline(o.y, M1, M2, M3, M4, M5, latitude_min, latitude_max);
o.z = filmic_spline(o.z, M1, M2, M3, M4, M5, latitude_min, latitude_max);
o.x = filmic_spline(o.x, M1, M2, M3, M4, M5, latitude_min, latitude_max, type);
o.y = filmic_spline(o.y, M1, M2, M3, M4, M5, latitude_min, latitude_max, type);
o.z = filmic_spline(o.z, M1, M2, M3, M4, M5, latitude_min, latitude_max, type);

// Output power
o = native_powr(clamp(o, (float4)0.0f, (float4)1.0f), output_power);
Expand All @@ -327,7 +388,8 @@ filmicrgb_split (read_only image2d_t in, write_only image2d_t out,
const float sigma_toe, const float sigma_shoulder, const float saturation,
const float4 M1, const float4 M2, const float4 M3, const float4 M4, const float4 M5,
const float latitude_min, const float latitude_max, const float output_power,
const dt_iop_filmicrgb_colorscience_type_t color_science)
const dt_iop_filmicrgb_colorscience_type_t color_science,
const dt_iop_filmicrgb_curve_type_t type_1, const dt_iop_filmicrgb_curve_type_t type_2)
{
const unsigned int x = get_global_id(0);
const unsigned int y = get_global_id(1);
Expand All @@ -337,14 +399,16 @@ filmicrgb_split (read_only image2d_t in, write_only image2d_t out,
const float4 i = read_imagef(in, sampleri, (int2)(x, y));
float4 o;

const dt_iop_filmicrgb_curve_type_t type[2] = { type_1, type_2 };

switch(color_science)
{
case DT_FILMIC_COLORSCIENCE_V1:
{
o = filmic_split_v1(i, dynamic_range, black_exposure, grey_value,
profile_info, lut, use_work_profile,
sigma_toe, sigma_shoulder, saturation,
M1, M2, M3, M4, M5, latitude_min, latitude_max, output_power);
M1, M2, M3, M4, M5, latitude_min, latitude_max, output_power, type);
break;
}
case DT_FILMIC_COLORSCIENCE_V2:
Expand All @@ -353,7 +417,7 @@ filmicrgb_split (read_only image2d_t in, write_only image2d_t out,
o = filmic_split_v2_v3(i, dynamic_range, black_exposure, grey_value,
profile_info, lut, use_work_profile,
sigma_toe, sigma_shoulder, saturation,
M1, M2, M3, M4, M5, latitude_min, latitude_max, output_power);
M1, M2, M3, M4, M5, latitude_min, latitude_max, output_power, type);
break;
}
}
Expand All @@ -371,7 +435,8 @@ inline float4 filmic_chroma_v1(const float4 i,
const float sigma_toe, const float sigma_shoulder, const float saturation,
const float4 M1, const float4 M2, const float4 M3, const float4 M4, const float4 M5,
const float latitude_min, const float latitude_max, const float output_power,
const dt_iop_filmicrgb_methods_type_t variant)
const dt_iop_filmicrgb_methods_type_t variant,
const dt_iop_filmicrgb_curve_type_t type[2])
{
float norm = fmax(get_pixel_norm(i, variant, profile_info, lut, use_work_profile), NORM_MIN);

Expand All @@ -398,7 +463,7 @@ inline float4 filmic_chroma_v1(const float4 i,

// Filmic S curve on the max RGB
// Apply the transfer function of the display
norm = native_powr(clamp(filmic_spline(norm, M1, M2, M3, M4, M5, latitude_min, latitude_max), 0.0f, 1.0f), output_power);
norm = native_powr(clamp(filmic_spline(norm, M1, M2, M3, M4, M5, latitude_min, latitude_max, type), 0.0f, 1.0f), output_power);

return o * norm;
}
Expand All @@ -412,7 +477,8 @@ inline float4 filmic_chroma_v2_v3(const float4 i,
const float4 M1, const float4 M2, const float4 M3, const float4 M4, const float4 M5,
const float latitude_min, const float latitude_max, const float output_power,
const dt_iop_filmicrgb_methods_type_t variant,
const dt_iop_filmicrgb_colorscience_type_t colorscience_version)
const dt_iop_filmicrgb_colorscience_type_t colorscience_version,
const dt_iop_filmicrgb_curve_type_t type[2])
{
float norm = fmax(get_pixel_norm(i, variant, profile_info, lut, use_work_profile), NORM_MIN);

Expand All @@ -431,7 +497,7 @@ inline float4 filmic_chroma_v2_v3(const float4 i,

// Filmic S curve on the max RGB
// Apply the transfer function of the display
norm = native_powr(clamp(filmic_spline(norm, M1, M2, M3, M4, M5, latitude_min, latitude_max), 0.0f, 1.0f), output_power);
norm = native_powr(clamp(filmic_spline(norm, M1, M2, M3, M4, M5, latitude_min, latitude_max, type), 0.0f, 1.0f), output_power);

// Re-apply ratios with saturation change
ratios = fmax(ratios + ((float4)1.0f - ratios) * ((float4)1.0f - desaturation), (float4)0.f);
Expand Down Expand Up @@ -465,7 +531,8 @@ filmicrgb_chroma (read_only image2d_t in, write_only image2d_t out,
const float4 M1, const float4 M2, const float4 M3, const float4 M4, const float4 M5,
const float latitude_min, const float latitude_max, const float output_power,
const dt_iop_filmicrgb_methods_type_t variant,
const dt_iop_filmicrgb_colorscience_type_t color_science)
const dt_iop_filmicrgb_colorscience_type_t color_science,
const dt_iop_filmicrgb_curve_type_t type_1, const dt_iop_filmicrgb_curve_type_t type_2)
{
const unsigned int x = get_global_id(0);
const unsigned int y = get_global_id(1);
Expand All @@ -475,14 +542,16 @@ filmicrgb_chroma (read_only image2d_t in, write_only image2d_t out,
const float4 i = read_imagef(in, sampleri, (int2)(x, y));
float4 o;

const dt_iop_filmicrgb_curve_type_t type[2] = { type_1, type_2 };

switch(color_science)
{
case DT_FILMIC_COLORSCIENCE_V1:
{
o = filmic_chroma_v1(i, dynamic_range, black_exposure, grey_value,
profile_info, lut, use_work_profile,
sigma_toe, sigma_shoulder, saturation,
M1, M2, M3, M4, M5, latitude_min, latitude_max, output_power, variant);
M1, M2, M3, M4, M5, latitude_min, latitude_max, output_power, variant, type);
break;
}
case DT_FILMIC_COLORSCIENCE_V2:
Expand All @@ -492,7 +561,7 @@ filmicrgb_chroma (read_only image2d_t in, write_only image2d_t out,
profile_info, lut, use_work_profile,
sigma_toe, sigma_shoulder, saturation,
M1, M2, M3, M4, M5, latitude_min, latitude_max, output_power, variant,
color_science);
color_science, type);
break;
}
}
Expand Down