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FFmpeg/libswscale/cms.c

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/*
* Copyright (C) 2024 Niklas Haas
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <math.h>
#include <string.h>
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/csp.h"
#include "libavutil/slicethread.h"
#include "cms.h"
#include "csputils.h"
#include "libswscale/swscale.h"
#include "utils.h"
bool sws_color_map_noop(const SwsColorMap *map)
{
/* If the encoding space is different, we must go through a conversion */
if (map->src.prim != map->dst.prim || map->src.trc != map->dst.trc)
return false;
/* If the black point changes, we have to perform black point compensation */
if (av_cmp_q(map->src.min_luma, map->dst.min_luma))
return false;
switch (map->intent) {
case SWS_INTENT_ABSOLUTE_COLORIMETRIC:
case SWS_INTENT_RELATIVE_COLORIMETRIC:
return ff_prim_superset(&map->dst.gamut, &map->src.gamut) &&
av_cmp_q(map->src.max_luma, map->dst.max_luma) <= 0;
case SWS_INTENT_PERCEPTUAL:
case SWS_INTENT_SATURATION:
return ff_prim_equal(&map->dst.gamut, &map->src.gamut) &&
!av_cmp_q(map->src.max_luma, map->dst.max_luma);
default:
av_assert0(!"Invalid gamut mapping intent?");
return true;
}
}
/* Approximation of gamut hull at a given intensity level */
static const float hull(float I)
{
return ((I - 6.0f) * I + 9.0f) * I;
}
/* For some minimal type safety, and code cleanliness */
typedef struct RGB {
float R, G, B; /* nits */
} RGB;
typedef struct IPT {
float I, P, T;
} IPT;
typedef struct ICh {
float I, C, h;
} ICh;
static av_always_inline ICh ipt2ich(IPT c)
{
return (ICh) {
.I = c.I,
.C = sqrtf(c.P * c.P + c.T * c.T),
.h = atan2f(c.T, c.P),
};
}
static av_always_inline IPT ich2ipt(ICh c)
{
return (IPT) {
.I = c.I,
.P = c.C * cosf(c.h),
.T = c.C * sinf(c.h),
};
}
/* Helper struct containing pre-computed cached values describing a gamut */
typedef struct Gamut {
SwsMatrix3x3 encoding2lms;
SwsMatrix3x3 lms2encoding;
SwsMatrix3x3 lms2content;
SwsMatrix3x3 content2lms;
av_csp_eotf_function eotf;
av_csp_eotf_function eotf_inv;
float Iavg_frame;
float Imax_frame;
float Imin, Imax;
float Lb, Lw;
AVCIExy wp;
ICh peak; /* updated as needed in loop body when hue changes */
} Gamut;
static Gamut gamut_from_colorspace(SwsColor fmt)
{
const AVColorPrimariesDesc *encoding = av_csp_primaries_desc_from_id(fmt.prim);
const AVColorPrimariesDesc content = {
.prim = fmt.gamut,
.wp = encoding->wp,
};
const float Lw = av_q2d(fmt.max_luma), Lb = av_q2d(fmt.min_luma);
const float Imax = pq_oetf(Lw);
return (Gamut) {
.encoding2lms = ff_sws_ipt_rgb2lms(encoding),
.lms2encoding = ff_sws_ipt_lms2rgb(encoding),
.lms2content = ff_sws_ipt_lms2rgb(&content),
.content2lms = ff_sws_ipt_rgb2lms(&content),
.eotf = av_csp_itu_eotf(fmt.trc),
.eotf_inv = av_csp_itu_eotf_inv(fmt.trc),
.wp = encoding->wp,
.Imin = pq_oetf(Lb),
.Imax = Imax,
.Imax_frame = fmt.frame_peak.den ? pq_oetf(av_q2d(fmt.frame_peak)) : Imax,
.Iavg_frame = fmt.frame_avg.den ? pq_oetf(av_q2d(fmt.frame_avg)) : 0.0f,
.Lb = Lb,
.Lw = Lw,
};
}
static av_always_inline IPT rgb2ipt(RGB c, const SwsMatrix3x3 rgb2lms)
{
const float L = rgb2lms.m[0][0] * c.R +
rgb2lms.m[0][1] * c.G +
rgb2lms.m[0][2] * c.B;
const float M = rgb2lms.m[1][0] * c.R +
rgb2lms.m[1][1] * c.G +
rgb2lms.m[1][2] * c.B;
const float S = rgb2lms.m[2][0] * c.R +
rgb2lms.m[2][1] * c.G +
rgb2lms.m[2][2] * c.B;
const float Lp = pq_oetf(L);
const float Mp = pq_oetf(M);
const float Sp = pq_oetf(S);
return (IPT) {
.I = 0.4000f * Lp + 0.4000f * Mp + 0.2000f * Sp,
.P = 4.4550f * Lp - 4.8510f * Mp + 0.3960f * Sp,
.T = 0.8056f * Lp + 0.3572f * Mp - 1.1628f * Sp,
};
}
static av_always_inline RGB ipt2rgb(IPT c, const SwsMatrix3x3 lms2rgb)
{
const float Lp = c.I + 0.0975689f * c.P + 0.205226f * c.T;
const float Mp = c.I - 0.1138760f * c.P + 0.133217f * c.T;
const float Sp = c.I + 0.0326151f * c.P - 0.676887f * c.T;
const float L = pq_eotf(Lp);
const float M = pq_eotf(Mp);
const float S = pq_eotf(Sp);
return (RGB) {
.R = lms2rgb.m[0][0] * L +
lms2rgb.m[0][1] * M +
lms2rgb.m[0][2] * S,
.G = lms2rgb.m[1][0] * L +
lms2rgb.m[1][1] * M +
lms2rgb.m[1][2] * S,
.B = lms2rgb.m[2][0] * L +
lms2rgb.m[2][1] * M +
lms2rgb.m[2][2] * S,
};
}
static inline bool ingamut(IPT c, Gamut gamut)
{
const float min_rgb = gamut.Lb - 1e-4f;
const float max_rgb = gamut.Lw + 1e-2f;
const float Lp = c.I + 0.0975689f * c.P + 0.205226f * c.T;
const float Mp = c.I - 0.1138760f * c.P + 0.133217f * c.T;
const float Sp = c.I + 0.0326151f * c.P - 0.676887f * c.T;
if (Lp < gamut.Imin || Lp > gamut.Imax ||
Mp < gamut.Imin || Mp > gamut.Imax ||
Sp < gamut.Imin || Sp > gamut.Imax)
{
/* Values outside legal LMS range */
return false;
} else {
const float L = pq_eotf(Lp);
const float M = pq_eotf(Mp);
const float S = pq_eotf(Sp);
RGB rgb = {
.R = gamut.lms2content.m[0][0] * L +
gamut.lms2content.m[0][1] * M +
gamut.lms2content.m[0][2] * S,
.G = gamut.lms2content.m[1][0] * L +
gamut.lms2content.m[1][1] * M +
gamut.lms2content.m[1][2] * S,
.B = gamut.lms2content.m[2][0] * L +
gamut.lms2content.m[2][1] * M +
gamut.lms2content.m[2][2] * S,
};
return rgb.R >= min_rgb && rgb.R <= max_rgb &&
rgb.G >= min_rgb && rgb.G <= max_rgb &&
rgb.B >= min_rgb && rgb.B <= max_rgb;
}
}
static const float maxDelta = 5e-5f;
// Find gamut intersection using specified bounds
static inline ICh
desat_bounded(float I, float h, float Cmin, float Cmax, Gamut gamut)
{
if (I <= gamut.Imin)
return (ICh) { .I = gamut.Imin, .C = 0, .h = h };
else if (I >= gamut.Imax)
return (ICh) { .I = gamut.Imax, .C = 0, .h = h };
else {
const float maxDI = I * maxDelta;
ICh res = { .I = I, .C = (Cmin + Cmax) / 2, .h = h };
do {
if (ingamut(ich2ipt(res), gamut)) {
Cmin = res.C;
} else {
Cmax = res.C;
}
res.C = (Cmin + Cmax) / 2;
} while (Cmax - Cmin > maxDI);
return res;
}
}
// Finds maximally saturated in-gamut color (for given hue)
static inline ICh saturate(float hue, Gamut gamut)
{
static const float invphi = 0.6180339887498948f;
static const float invphi2 = 0.38196601125010515f;
ICh lo = { .I = gamut.Imin, .h = hue };
ICh hi = { .I = gamut.Imax, .h = hue };
float de = hi.I - lo.I;
ICh a = { .I = lo.I + invphi2 * de };
ICh b = { .I = lo.I + invphi * de };
a = desat_bounded(a.I, hue, 0.0f, 0.5f, gamut);
b = desat_bounded(b.I, hue, 0.0f, 0.5f, gamut);
while (de > maxDelta) {
de *= invphi;
if (a.C > b.C) {
hi = b;
b = a;
a.I = lo.I + invphi2 * de;
a = desat_bounded(a.I, hue, lo.C - maxDelta, 0.5f, gamut);
} else {
lo = a;
a = b;
b.I = lo.I + invphi * de;
b = desat_bounded(b.I, hue, hi.C - maxDelta, 0.5f, gamut);
}
}
return a.C > b.C ? a : b;
}
static float softclip(float value, float source, float target)
{
const float j = SOFTCLIP_KNEE;
float peak, x, a, b, scale;
if (!target)
return 0.0f;
peak = source / target;
x = fminf(value / target, peak);
if (x <= j || peak <= 1.0)
return value;
/* Apply simple mobius function */
a = -j*j * (peak - 1.0f) / (j*j - 2.0f * j + peak);
b = (j*j - 2.0f * j * peak + peak) / fmaxf(1e-6f, peak - 1.0f);
scale = (b*b + 2.0f * b*j + j*j) / (b - a);
return scale * (x + a) / (x + b) * target;
}
/**
* Something like fmixf(base, c, x) but follows an exponential curve, note
* that this can be used to extend 'c' outwards for x > 1
*/
static inline ICh mix_exp(ICh c, float x, float gamma, float base)
{
return (ICh) {
.I = base + (c.I - base) * powf(x, gamma),
.C = c.C * x,
.h = c.h,
};
}
/**
* Drop gamma for colors approaching black and achromatic to avoid numerical
* instabilities, and excessive brightness boosting of grain, while also
* strongly boosting gamma for values exceeding the target peak
*/
static inline float scale_gamma(float gamma, ICh ich, Gamut gamut)
{
const float Imin = gamut.Imin;
const float Irel = fmaxf((ich.I - Imin) / (gamut.peak.I - Imin), 0.0f);
return gamma * powf(Irel, 3) * fminf(ich.C / gamut.peak.C, 1.0f);
}
/* Clip a color along the exponential curve given by `gamma` */
static inline IPT clip_gamma(IPT ipt, float gamma, Gamut gamut)
{
float lo = 0.0f, hi = 1.0f, x = 0.5f;
const float maxDI = fmaxf(ipt.I * maxDelta, 1e-7f);
ICh ich;
if (ipt.I <= gamut.Imin)
return (IPT) { .I = gamut.Imin };
if (ingamut(ipt, gamut))
return ipt;
ich = ipt2ich(ipt);
if (!gamma)
return ich2ipt(desat_bounded(ich.I, ich.h, 0.0f, ich.C, gamut));
gamma = scale_gamma(gamma, ich, gamut);
do {
ICh test = mix_exp(ich, x, gamma, gamut.peak.I);
if (ingamut(ich2ipt(test), gamut)) {
lo = x;
} else {
hi = x;
}
x = (lo + hi) / 2.0f;
} while (hi - lo > maxDI);
return ich2ipt(mix_exp(ich, x, gamma, gamut.peak.I));
}
typedef struct CmsCtx CmsCtx;
struct CmsCtx {
/* Tone mapping parameters */
float Qa, Qb, Qc, Pa, Pb, src_knee, dst_knee; /* perceptual */
float I_scale, I_offset; /* linear methods */
/* Colorspace parameters */
Gamut src;
Gamut tmp; /* after tone mapping */
Gamut dst;
SwsMatrix3x3 adaptation; /* for absolute intent */
/* Invocation parameters */
SwsColorMap map;
float (*tone_map)(const CmsCtx *ctx, float I);
IPT (*adapt_colors)(const CmsCtx *ctx, IPT ipt);
v3u16_t *input;
v3u16_t *output;
/* Threading parameters */
int slice_size;
int size_input;
int size_output_I;
int size_output_PT;
};
/**
* Helper function to pick a knee point based on the * HDR10+ brightness
* metadata and scene brightness average matching.
*
* Inspired by SMPTE ST2094-10, with some modifications
*/
static void st2094_pick_knee(float src_max, float src_min, float src_avg,
float dst_max, float dst_min,
float *out_src_knee, float *out_dst_knee)
{
const float min_knee = PERCEPTUAL_KNEE_MIN;
const float max_knee = PERCEPTUAL_KNEE_MAX;
const float def_knee = PERCEPTUAL_KNEE_DEF;
const float src_knee_min = fmixf(src_min, src_max, min_knee);
const float src_knee_max = fmixf(src_min, src_max, max_knee);
const float dst_knee_min = fmixf(dst_min, dst_max, min_knee);
const float dst_knee_max = fmixf(dst_min, dst_max, max_knee);
float src_knee, target, adapted, tuning, adaptation, dst_knee;
/* Choose source knee based on dynamic source scene brightness */
src_knee = src_avg ? src_avg : fmixf(src_min, src_max, def_knee);
src_knee = av_clipf(src_knee, src_knee_min, src_knee_max);
/* Choose target adaptation point based on linearly re-scaling source knee */
target = (src_knee - src_min) / (src_max - src_min);
adapted = fmixf(dst_min, dst_max, target);
/**
* Choose the destnation knee by picking the perceptual adaptation point
* between the source knee and the desired target. This moves the knee
* point, on the vertical axis, closer to the 1:1 (neutral) line.
*
* Adjust the adaptation strength towards 1 based on how close the knee
* point is to its extreme values (min/max knee)
*/
tuning = smoothstepf(max_knee, def_knee, target) *
smoothstepf(min_knee, def_knee, target);
adaptation = fmixf(1.0f, PERCEPTUAL_ADAPTATION, tuning);
dst_knee = fmixf(src_knee, adapted, adaptation);
dst_knee = av_clipf(dst_knee, dst_knee_min, dst_knee_max);
*out_src_knee = src_knee;
*out_dst_knee = dst_knee;
}
static void tone_map_setup(CmsCtx *ctx, bool dynamic)
{
const float dst_min = ctx->dst.Imin;
const float dst_max = ctx->dst.Imax;
const float src_min = ctx->src.Imin;
const float src_max = dynamic ? ctx->src.Imax_frame : ctx->src.Imax;
const float src_avg = dynamic ? ctx->src.Iavg_frame : 0.0f;
float slope, ratio, in_min, in_max, out_min, out_max, t;
switch (ctx->map.intent) {
case SWS_INTENT_PERCEPTUAL:
st2094_pick_knee(src_max, src_min, src_avg, dst_max, dst_min,
&ctx->src_knee, &ctx->dst_knee);
/* Solve for linear knee (Pa = 0) */
slope = (ctx->dst_knee - dst_min) / (ctx->src_knee - src_min);
/**
* Tune the slope at the knee point slightly: raise it to a user-provided
* gamma exponent, multiplied by an extra tuning coefficient designed to
* make the slope closer to 1.0 when the difference in peaks is low, and
* closer to linear when the difference between peaks is high.
*/
ratio = src_max / dst_max - 1.0f;
ratio = av_clipf(SLOPE_TUNING * ratio, SLOPE_OFFSET, 1.0f + SLOPE_OFFSET);
slope = powf(slope, (1.0f - PERCEPTUAL_CONTRAST) * ratio);
/* Normalize everything the pivot to make the math easier */
in_min = src_min - ctx->src_knee;
in_max = src_max - ctx->src_knee;
out_min = dst_min - ctx->dst_knee;
out_max = dst_max - ctx->dst_knee;
/**
* Solve P of order 2 for:
* P(in_min) = out_min
* P'(0.0) = slope
* P(0.0) = 0.0
*/
ctx->Pa = (out_min - slope * in_min) / (in_min * in_min);
ctx->Pb = slope;
/**
* Solve Q of order 3 for:
* Q(in_max) = out_max
* Q''(in_max) = 0.0
* Q(0.0) = 0.0
* Q'(0.0) = slope
*/
t = 2 * in_max * in_max;
ctx->Qa = (slope * in_max - out_max) / (in_max * t);
ctx->Qb = -3 * (slope * in_max - out_max) / t;
ctx->Qc = slope;
break;
case SWS_INTENT_SATURATION:
/* Linear stretch */
ctx->I_scale = (dst_max - dst_min) / (src_max - src_min);
ctx->I_offset = dst_min - src_min * ctx->I_scale;
break;
case SWS_INTENT_RELATIVE_COLORIMETRIC:
/* Pure black point adaptation */
ctx->I_scale = src_max / (src_max - src_min) /
(dst_max / (dst_max - dst_min));
ctx->I_offset = dst_min - src_min * ctx->I_scale;
break;
case SWS_INTENT_ABSOLUTE_COLORIMETRIC:
/* Hard clip */
ctx->I_scale = 1.0f;
ctx->I_offset = 0.0f;
break;
}
}
static av_always_inline IPT tone_map_apply(const CmsCtx *ctx, IPT ipt)
{
float I = ipt.I, desat;
if (ctx->map.intent == SWS_INTENT_PERCEPTUAL) {
const float Pa = ctx->Pa, Pb = ctx->Pb;
const float Qa = ctx->Qa, Qb = ctx->Qb, Qc = ctx->Qc;
I -= ctx->src_knee;
I = I > 0 ? ((Qa * I + Qb) * I + Qc) * I : (Pa * I + Pb) * I;
I += ctx->dst_knee;
} else {
I = ctx->I_scale * I + ctx->I_offset;
}
/**
* Avoids raising saturation excessively when raising brightness, and
* also desaturates when reducing brightness greatly to account for the
* reduction in gamut volume.
*/
desat = fminf(ipt.I / I, hull(I) / hull(ipt.I));
return (IPT) {
.I = I,
.P = ipt.P * desat,
.T = ipt.T * desat,
};
}
static IPT perceptual(const CmsCtx *ctx, IPT ipt)
{
ICh ich = ipt2ich(ipt);
IPT mapped = rgb2ipt(ipt2rgb(ipt, ctx->tmp.lms2content), ctx->dst.content2lms);
RGB rgb;
float maxRGB;
/* Protect in gamut region */
const float maxC = fmaxf(ctx->tmp.peak.C, ctx->dst.peak.C);
float k = smoothstepf(PERCEPTUAL_DEADZONE, 1.0f, ich.C / maxC);
k *= PERCEPTUAL_STRENGTH;
ipt.I = fmixf(ipt.I, mapped.I, k);
ipt.P = fmixf(ipt.P, mapped.P, k);
ipt.T = fmixf(ipt.T, mapped.T, k);
rgb = ipt2rgb(ipt, ctx->dst.lms2content);
maxRGB = fmaxf(rgb.R, fmaxf(rgb.G, rgb.B));
rgb.R = fmaxf(softclip(rgb.R, maxRGB, ctx->dst.Lw), ctx->dst.Lb);
rgb.G = fmaxf(softclip(rgb.G, maxRGB, ctx->dst.Lw), ctx->dst.Lb);
rgb.B = fmaxf(softclip(rgb.B, maxRGB, ctx->dst.Lw), ctx->dst.Lb);
return rgb2ipt(rgb, ctx->dst.content2lms);
}
static IPT relative(const CmsCtx *ctx, IPT ipt)
{
return clip_gamma(ipt, COLORIMETRIC_GAMMA, ctx->dst);
}
static IPT absolute(const CmsCtx *ctx, IPT ipt)
{
RGB rgb = ipt2rgb(ipt, ctx->dst.lms2encoding);
float c[3] = { rgb.R, rgb.G, rgb.B };
ff_sws_matrix3x3_apply(&ctx->adaptation, c);
ipt = rgb2ipt((RGB) { c[0], c[1], c[2] }, ctx->dst.encoding2lms);
return clip_gamma(ipt, COLORIMETRIC_GAMMA, ctx->dst);
}
static IPT saturation(const CmsCtx * ctx, IPT ipt)
{
RGB rgb = ipt2rgb(ipt, ctx->tmp.lms2content);
return rgb2ipt(rgb, ctx->dst.content2lms);
}
static av_always_inline av_const uint16_t av_round16f(float x)
{
return av_clip_uint16(x * (UINT16_MAX - 1) + 0.5f);
}
/* Call this whenever the hue changes inside the loop body */
static av_always_inline void update_hue_peaks(CmsCtx *ctx, float P, float T)
{
const float hue = atan2f(T, P);
switch (ctx->map.intent) {
case SWS_INTENT_PERCEPTUAL:
ctx->tmp.peak = saturate(hue, ctx->tmp);
/* fall through */
case SWS_INTENT_RELATIVE_COLORIMETRIC:
case SWS_INTENT_ABSOLUTE_COLORIMETRIC:
ctx->dst.peak = saturate(hue, ctx->dst);
return;
default:
return;
}
}
static void generate_slice(void *priv, int jobnr, int threadnr, int nb_jobs,
int nb_threads)
{
CmsCtx ctx = *(const CmsCtx *) priv;
const int slice_start = jobnr * ctx.slice_size;
const int slice_stride = ctx.size_input * ctx.size_input;
const int slice_end = FFMIN((jobnr + 1) * ctx.slice_size, ctx.size_input);
v3u16_t *input = &ctx.input[slice_start * slice_stride];
const int output_slice_h = (ctx.size_output_PT + nb_jobs - 1) / nb_jobs;
const int output_start = jobnr * output_slice_h;
const int output_stride = ctx.size_output_PT * ctx.size_output_I;
const int output_end = FFMIN((jobnr + 1) * output_slice_h, ctx.size_output_PT);
v3u16_t *output = ctx.output ? &ctx.output[output_start * output_stride] : NULL;
const float I_scale = 1.0f / (ctx.src.Imax - ctx.src.Imin);
const float I_offset = -ctx.src.Imin * I_scale;
const float PT_offset = (float) (1 << 15) / (UINT16_MAX - 1);
const float input_scale = 1.0f / (ctx.size_input - 1);
const float output_scale_PT = 1.0f / (ctx.size_output_PT - 1);
const float output_scale_I = (ctx.tmp.Imax - ctx.tmp.Imin) /
(ctx.size_output_I - 1);
for (int Bx = slice_start; Bx < slice_end; Bx++) {
const float B = input_scale * Bx;
for (int Gx = 0; Gx < ctx.size_input; Gx++) {
const float G = input_scale * Gx;
for (int Rx = 0; Rx < ctx.size_input; Rx++) {
double c[3] = { input_scale * Rx, G, B };
RGB rgb;
IPT ipt;
ctx.src.eotf(ctx.src.Lw, ctx.src.Lb, c);
rgb = (RGB) { c[0], c[1], c[2] };
ipt = rgb2ipt(rgb, ctx.src.encoding2lms);
if (output) {
/* Save intermediate value to 3DLUT */
*input++ = (v3u16_t) {
av_round16f(I_scale * ipt.I + I_offset),
av_round16f(ipt.P + PT_offset),
av_round16f(ipt.T + PT_offset),
};
} else {
update_hue_peaks(&ctx, ipt.P, ipt.T);
ipt = tone_map_apply(&ctx, ipt);
ipt = ctx.adapt_colors(&ctx, ipt);
rgb = ipt2rgb(ipt, ctx.dst.lms2encoding);
c[0] = rgb.R;
c[1] = rgb.G;
c[2] = rgb.B;
ctx.dst.eotf_inv(ctx.dst.Lw, ctx.dst.Lb, c);
*input++ = (v3u16_t) {
av_round16f(c[0]),
av_round16f(c[1]),
av_round16f(c[2]),
};
}
}
}
}
if (!output)
return;
/* Generate split gamut mapping LUT */
for (int Tx = output_start; Tx < output_end; Tx++) {
const float T = output_scale_PT * Tx - PT_offset;
for (int Px = 0; Px < ctx.size_output_PT; Px++) {
const float P = output_scale_PT * Px - PT_offset;
update_hue_peaks(&ctx, P, T);
for (int Ix = 0; Ix < ctx.size_output_I; Ix++) {
const float I = output_scale_I * Ix + ctx.tmp.Imin;
IPT ipt = ctx.adapt_colors(&ctx, (IPT) { I, P, T });
RGB rgb = ipt2rgb(ipt, ctx.dst.lms2encoding);
double c[3] = { rgb.R, rgb.G, rgb.B };
ctx.dst.eotf_inv(ctx.dst.Lw, ctx.dst.Lb, c);
*output++ = (v3u16_t) {
av_round16f(c[0]),
av_round16f(c[1]),
av_round16f(c[2]),
};
}
}
}
}
int sws_color_map_generate_static(v3u16_t *lut, int size, const SwsColorMap *map)
{
return sws_color_map_generate_dynamic(lut, NULL, size, 1, 1, map);
}
int sws_color_map_generate_dynamic(v3u16_t *input, v3u16_t *output,
int size_input, int size_I, int size_PT,
const SwsColorMap *map)
{
AVSliceThread *slicethread;
int ret, num_slices;
CmsCtx ctx = {
.map = *map,
.input = input,
.output = output,
.size_input = size_input,
.size_output_I = size_I,
.size_output_PT = size_PT,
.src = gamut_from_colorspace(map->src),
.dst = gamut_from_colorspace(map->dst),
};
switch (ctx.map.intent) {
case SWS_INTENT_PERCEPTUAL: ctx.adapt_colors = perceptual; break;
case SWS_INTENT_RELATIVE_COLORIMETRIC: ctx.adapt_colors = relative; break;
case SWS_INTENT_SATURATION: ctx.adapt_colors = saturation; break;
case SWS_INTENT_ABSOLUTE_COLORIMETRIC: ctx.adapt_colors = absolute; break;
default: return AVERROR(EINVAL);
}
if (!output) {
/* Tone mapping is handled in a separate step when using dynamic TM */
tone_map_setup(&ctx, false);
}
/* Intermediate color space after tone mapping */
ctx.tmp = ctx.src;
ctx.tmp.Lb = ctx.dst.Lb;
ctx.tmp.Lw = ctx.dst.Lw;
ctx.tmp.Imin = ctx.dst.Imin;
ctx.tmp.Imax = ctx.dst.Imax;
if (ctx.map.intent == SWS_INTENT_ABSOLUTE_COLORIMETRIC) {
/**
* The IPT transform already implies an explicit white point adaptation
* from src to dst, so to get absolute colorimetric semantics we have
* to explicitly undo this adaptation with a * corresponding inverse.
*/
ctx.adaptation = ff_sws_get_adaptation(&ctx.map.dst.gamut,
ctx.dst.wp, ctx.src.wp);
}
ret = avpriv_slicethread_create(&slicethread, &ctx, generate_slice, NULL, 0);
if (ret < 0)
return ret;
ctx.slice_size = (ctx.size_input + ret - 1) / ret;
num_slices = (ctx.size_input + ctx.slice_size - 1) / ctx.slice_size;
avpriv_slicethread_execute(slicethread, num_slices, 0);
avpriv_slicethread_free(&slicethread);
return 0;
}
void sws_tone_map_generate(v2u16_t *lut, int size, const SwsColorMap *map)
{
CmsCtx ctx = {
.map = *map,
.src = gamut_from_colorspace(map->src),
.dst = gamut_from_colorspace(map->dst),
};
const float src_scale = (ctx.src.Imax - ctx.src.Imin) / (size - 1);
const float src_offset = ctx.src.Imin;
const float dst_scale = 1.0f / (ctx.dst.Imax - ctx.dst.Imin);
const float dst_offset = -ctx.dst.Imin * dst_scale;
tone_map_setup(&ctx, true);
for (int i = 0; i < size; i++) {
const float I = src_scale * i + src_offset;
IPT ipt = tone_map_apply(&ctx, (IPT) { I, 1.0f });
lut[i] = (v2u16_t) {
av_round16f(dst_scale * ipt.I + dst_offset),
av_clip_uint16(ipt.P * (1 << 15) + 0.5f),
};
}
}