/*
 * Copyright (c) 2000 John Walker
 * Copyright (c) 2016 Paul B Mahol
 *
 * 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 "libavutil/avassert.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "libavutil/parseutils.h"
#include "libavutil/pixdesc.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"

enum CieSystem {
    XYY,
    UCS,
    LUV,
    NB_CIE
};

enum ColorsSystems {
    NTSCsystem,
    EBUsystem,
    SMPTEsystem,
    SMPTE240Msystem,
    APPLEsystem,
    wRGBsystem,
    CIE1931system,
    Rec709system,
    Rec2020system,
    NB_CS
};

typedef struct CiescopeContext {
    const AVClass *class;
    int color_system;
    unsigned gamuts;
    int size;
    int show_white;
    int correct_gamma;
    int cie;
    float intensity;
    float contrast;
    int background;

    double log2lin[65536];
    double igamma;
    double i[3][3];
    double m[3][3];
    AVFrame *f;
    void (*filter)(AVFilterContext *ctx, AVFrame *in, double *cx, double *cy, int x, int y);
} CiescopeContext;

#define OFFSET(x) offsetof(CiescopeContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

static const AVOption ciescope_options[] = {
    { "system",     "set color system", OFFSET(color_system), AV_OPT_TYPE_INT, {.i64=Rec709system}, 0, NB_CS-1, FLAGS, "system" },
    {   "ntsc",       "NTSC 1953 Y'I'O' (ITU-R BT.470 System M)", 0, AV_OPT_TYPE_CONST, {.i64=NTSCsystem},     0, 0, FLAGS, "system" },
    {   "470m",       "NTSC 1953 Y'I'O' (ITU-R BT.470 System M)", 0, AV_OPT_TYPE_CONST, {.i64=NTSCsystem},     0, 0, FLAGS, "system" },
    {   "ebu",        "EBU Y'U'V' (PAL/SECAM) (ITU-R BT.470 System B, G)", 0, AV_OPT_TYPE_CONST, {.i64=EBUsystem},      0, 0, FLAGS, "system" },
    {   "470bg",      "EBU Y'U'V' (PAL/SECAM) (ITU-R BT.470 System B, G)", 0, AV_OPT_TYPE_CONST, {.i64=EBUsystem},      0, 0, FLAGS, "system" },
    {   "smpte",      "SMPTE-C RGB",            0, AV_OPT_TYPE_CONST, {.i64=SMPTEsystem},    0, 0, FLAGS, "system" },
    {   "240m",       "SMPTE-240M Y'PbPr",      0, AV_OPT_TYPE_CONST, {.i64=SMPTE240Msystem},0, 0, FLAGS, "system" },
    {   "apple",      "Apple RGB",              0, AV_OPT_TYPE_CONST, {.i64=APPLEsystem},    0, 0, FLAGS, "system" },
    {   "widergb",    "Adobe Wide Gamut RGB",   0, AV_OPT_TYPE_CONST, {.i64=wRGBsystem},     0, 0, FLAGS, "system" },
    {   "cie1931",    "CIE 1931 RGB",           0, AV_OPT_TYPE_CONST, {.i64=CIE1931system},  0, 0, FLAGS, "system" },
    {   "hdtv",       "ITU.BT-709 Y'CbCr",      0, AV_OPT_TYPE_CONST, {.i64=Rec709system},   0, 0, FLAGS, "system" },
    {   "rec709",     "ITU.BT-709 Y'CbCr",      0, AV_OPT_TYPE_CONST, {.i64=Rec709system},   0, 0, FLAGS, "system" },
    {   "uhdtv",      "ITU-R.BT-2020",          0, AV_OPT_TYPE_CONST, {.i64=Rec2020system},  0, 0, FLAGS, "system" },
    {   "rec2020",    "ITU-R.BT-2020",          0, AV_OPT_TYPE_CONST, {.i64=Rec2020system},  0, 0, FLAGS, "system" },
    { "cie",        "set cie system", OFFSET(cie), AV_OPT_TYPE_INT,   {.i64=XYY}, 0, NB_CIE-1, FLAGS, "cie" },
    {   "xyy",      "CIE 1931 xyY", 0, AV_OPT_TYPE_CONST, {.i64=XYY}, 0, 0, FLAGS, "cie" },
    {   "ucs",      "CIE 1960 UCS", 0, AV_OPT_TYPE_CONST, {.i64=UCS}, 0, 0, FLAGS, "cie" },
    {   "luv",      "CIE 1976 Luv", 0, AV_OPT_TYPE_CONST, {.i64=LUV}, 0, 0, FLAGS, "cie" },
    { "gamuts",     "set what gamuts to draw", OFFSET(gamuts), AV_OPT_TYPE_FLAGS, {.i64=0}, 0, 0xFFF, FLAGS, "gamuts" },
    {   "ntsc",     NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<NTSCsystem},      0, 0, FLAGS, "gamuts" },
    {   "470m",     NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<NTSCsystem},      0, 0, FLAGS, "gamuts" },
    {   "ebu",      NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<EBUsystem},       0, 0, FLAGS, "gamuts" },
    {   "470bg",    NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<EBUsystem},       0, 0, FLAGS, "gamuts" },
    {   "smpte",    NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<SMPTEsystem},     0, 0, FLAGS, "gamuts" },
    {   "240m",     NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<SMPTE240Msystem}, 0, 0, FLAGS, "gamuts" },
    {   "apple",    NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<APPLEsystem},     0, 0, FLAGS, "gamuts" },
    {   "widergb",  NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<wRGBsystem},      0, 0, FLAGS, "gamuts" },
    {   "cie1931",  NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<CIE1931system},   0, 0, FLAGS, "gamuts" },
    {   "hdtv",     NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<Rec709system},    0, 0, FLAGS, "gamuts" },
    {   "rec709",   NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<Rec709system},    0, 0, FLAGS, "gamuts" },
    {   "uhdtv",    NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<Rec2020system},   0, 0, FLAGS, "gamuts" },
    {   "rec2020",  NULL, 0, AV_OPT_TYPE_CONST, {.i64=1<<Rec2020system},   0, 0, FLAGS, "gamuts" },
    { "size",       "set ciescope size", OFFSET(size), AV_OPT_TYPE_INT, {.i64=512}, 256, 8192, FLAGS },
    { "s",          "set ciescope size", OFFSET(size), AV_OPT_TYPE_INT, {.i64=512}, 256, 8192, FLAGS },
    { "intensity",  "set ciescope intensity", OFFSET(intensity), AV_OPT_TYPE_FLOAT, {.dbl=0.001}, 0, 1, FLAGS },
    { "i",          "set ciescope intensity", OFFSET(intensity), AV_OPT_TYPE_FLOAT, {.dbl=0.001}, 0, 1, FLAGS },
    { "contrast",   NULL, OFFSET(contrast), AV_OPT_TYPE_FLOAT, {.dbl=0.75},  0, 1, FLAGS },
    { "corrgamma",  NULL, OFFSET(correct_gamma), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, FLAGS },
    { "showwhite",  NULL, OFFSET(show_white), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
    { "gamma",      NULL, OFFSET(igamma), AV_OPT_TYPE_DOUBLE, {.dbl=2.6}, 0.1, 6, FLAGS },
    { NULL }
};

AVFILTER_DEFINE_CLASS(ciescope);

static const enum AVPixelFormat in_pix_fmts[] = {
    AV_PIX_FMT_RGB24,
    AV_PIX_FMT_RGBA,
    AV_PIX_FMT_RGB48,
    AV_PIX_FMT_RGBA64,
    AV_PIX_FMT_XYZ12,
    AV_PIX_FMT_NONE
};

static const enum AVPixelFormat out_pix_fmts[] = {
    AV_PIX_FMT_RGBA64,
    AV_PIX_FMT_NONE
};

static int query_formats(AVFilterContext *ctx)
{
    int ret;

    if ((ret = ff_formats_ref(ff_make_format_list(in_pix_fmts), &ctx->inputs[0]->out_formats)) < 0)
        return ret;

    if ((ret = ff_formats_ref(ff_make_format_list(out_pix_fmts), &ctx->outputs[0]->in_formats)) < 0)
        return ret;

    return 0;
}

static int config_output(AVFilterLink *outlink)
{
    CiescopeContext *s = outlink->src->priv;

    outlink->h = outlink->w = s->size;
    outlink->sample_aspect_ratio = (AVRational){1,1};

    return 0;
}

/* A  color  system is defined by the CIE x and y  coordinates of its
   three primary illuminants and the x and y coordinates of the  white
   point. */

struct ColorSystem {
    double xRed, yRed,                /* Red primary illuminant */
           xGreen, yGreen,            /* Green primary illuminant */
           xBlue, yBlue,              /* Blue primary illuminant */
           xWhite, yWhite,            /* White point */
           gamma;             /* gamma of nonlinear correction */
};

static float const spectral_chromaticity[][3] = {
    { 0.175560, 0.005294, 0.819146 },
    { 0.175483, 0.005286, 0.819231 },
    { 0.175400, 0.005279, 0.819321 },
    { 0.175317, 0.005271, 0.819412 },
    { 0.175237, 0.005263, 0.819500 },
    { 0.175161, 0.005256, 0.819582 },
    { 0.175088, 0.005247, 0.819665 },
    { 0.175015, 0.005236, 0.819749 },
    { 0.174945, 0.005226, 0.819829 },
    { 0.174880, 0.005221, 0.819899 },
    { 0.174821, 0.005221, 0.819959 },
    { 0.174770, 0.005229, 0.820001 },
    { 0.174722, 0.005238, 0.820040 },
    { 0.174665, 0.005236, 0.820098 },
    { 0.174595, 0.005218, 0.820187 },
    { 0.174510, 0.005182, 0.820309 },
    { 0.174409, 0.005127, 0.820464 },
    { 0.174308, 0.005068, 0.820624 },
    { 0.174222, 0.005017, 0.820761 },
    { 0.174156, 0.004981, 0.820863 },
    { 0.174112, 0.004964, 0.820924 },
    { 0.174088, 0.004964, 0.820948 },
    { 0.174073, 0.004973, 0.820955 },
    { 0.174057, 0.004982, 0.820961 },
    { 0.174036, 0.004986, 0.820978 },
    { 0.174008, 0.004981, 0.821012 },
    { 0.173972, 0.004964, 0.821064 },
    { 0.173932, 0.004943, 0.821125 },
    { 0.173889, 0.004926, 0.821185 },
    { 0.173845, 0.004916, 0.821239 },
    { 0.173801, 0.004915, 0.821284 },
    { 0.173754, 0.004925, 0.821321 },
    { 0.173705, 0.004937, 0.821358 },
    { 0.173655, 0.004944, 0.821401 },
    { 0.173606, 0.004940, 0.821454 },
    { 0.173560, 0.004923, 0.821517 },
    { 0.173514, 0.004895, 0.821590 },
    { 0.173468, 0.004865, 0.821667 },
    { 0.173424, 0.004836, 0.821740 },
    { 0.173380, 0.004813, 0.821807 },
    { 0.173337, 0.004797, 0.821866 },
    { 0.173291, 0.004786, 0.821923 },
    { 0.173238, 0.004779, 0.821983 },
    { 0.173174, 0.004775, 0.822051 },
    { 0.173101, 0.004774, 0.822125 },
    { 0.173021, 0.004775, 0.822204 },
    { 0.172934, 0.004781, 0.822285 },
    { 0.172843, 0.004791, 0.822366 },
    { 0.172751, 0.004799, 0.822450 },
    { 0.172662, 0.004802, 0.822536 },
    { 0.172577, 0.004799, 0.822624 },
    { 0.172489, 0.004795, 0.822715 },
    { 0.172396, 0.004796, 0.822808 },
    { 0.172296, 0.004803, 0.822901 },
    { 0.172192, 0.004815, 0.822993 },
    { 0.172087, 0.004833, 0.823081 },
    { 0.171982, 0.004855, 0.823163 },
    { 0.171871, 0.004889, 0.823240 },
    { 0.171741, 0.004939, 0.823319 },
    { 0.171587, 0.005010, 0.823402 },
    { 0.171407, 0.005102, 0.823490 },
    { 0.171206, 0.005211, 0.823583 },
    { 0.170993, 0.005334, 0.823674 },
    { 0.170771, 0.005470, 0.823759 },
    { 0.170541, 0.005621, 0.823838 },
    { 0.170301, 0.005789, 0.823911 },
    { 0.170050, 0.005974, 0.823976 },
    { 0.169786, 0.006177, 0.824037 },
    { 0.169505, 0.006398, 0.824097 },
    { 0.169203, 0.006639, 0.824158 },
    { 0.168878, 0.006900, 0.824222 },
    { 0.168525, 0.007184, 0.824291 },
    { 0.168146, 0.007491, 0.824363 },
    { 0.167746, 0.007821, 0.824433 },
    { 0.167328, 0.008175, 0.824496 },
    { 0.166895, 0.008556, 0.824549 },
    { 0.166446, 0.008964, 0.824589 },
    { 0.165977, 0.009402, 0.824622 },
    { 0.165483, 0.009865, 0.824652 },
    { 0.164963, 0.010351, 0.824687 },
    { 0.164412, 0.010858, 0.824731 },
    { 0.163828, 0.011385, 0.824787 },
    { 0.163210, 0.011937, 0.824853 },
    { 0.162552, 0.012520, 0.824928 },
    { 0.161851, 0.013137, 0.825011 },
    { 0.161105, 0.013793, 0.825102 },
    { 0.160310, 0.014491, 0.825199 },
    { 0.159466, 0.015232, 0.825302 },
    { 0.158573, 0.016015, 0.825412 },
    { 0.157631, 0.016840, 0.825529 },
    { 0.156641, 0.017705, 0.825654 },
    { 0.155605, 0.018609, 0.825786 },
    { 0.154525, 0.019556, 0.825920 },
    { 0.153397, 0.020554, 0.826049 },
    { 0.152219, 0.021612, 0.826169 },
    { 0.150985, 0.022740, 0.826274 },
    { 0.149691, 0.023950, 0.826359 },
    { 0.148337, 0.025247, 0.826416 },
    { 0.146928, 0.026635, 0.826437 },
    { 0.145468, 0.028118, 0.826413 },
    { 0.143960, 0.029703, 0.826337 },
    { 0.142405, 0.031394, 0.826201 },
    { 0.140796, 0.033213, 0.825991 },
    { 0.139121, 0.035201, 0.825679 },
    { 0.137364, 0.037403, 0.825233 },
    { 0.135503, 0.039879, 0.824618 },
    { 0.133509, 0.042692, 0.823798 },
    { 0.131371, 0.045876, 0.822753 },
    { 0.129086, 0.049450, 0.821464 },
    { 0.126662, 0.053426, 0.819912 },
    { 0.124118, 0.057803, 0.818079 },
    { 0.121469, 0.062588, 0.815944 },
    { 0.118701, 0.067830, 0.813468 },
    { 0.115807, 0.073581, 0.810612 },
    { 0.112776, 0.079896, 0.807328 },
    { 0.109594, 0.086843, 0.803563 },
    { 0.106261, 0.094486, 0.799253 },
    { 0.102776, 0.102864, 0.794360 },
    { 0.099128, 0.112007, 0.788865 },
    { 0.095304, 0.121945, 0.782751 },
    { 0.091294, 0.132702, 0.776004 },
    { 0.087082, 0.144317, 0.768601 },
    { 0.082680, 0.156866, 0.760455 },
    { 0.078116, 0.170420, 0.751464 },
    { 0.073437, 0.185032, 0.741531 },
    { 0.068706, 0.200723, 0.730571 },
    { 0.063993, 0.217468, 0.718539 },
    { 0.059316, 0.235254, 0.705430 },
    { 0.054667, 0.254096, 0.691238 },
    { 0.050031, 0.274002, 0.675967 },
    { 0.045391, 0.294976, 0.659633 },
    { 0.040757, 0.316981, 0.642262 },
    { 0.036195, 0.339900, 0.623905 },
    { 0.031756, 0.363598, 0.604646 },
    { 0.027494, 0.387921, 0.584584 },
    { 0.023460, 0.412703, 0.563837 },
    { 0.019705, 0.437756, 0.542539 },
    { 0.016268, 0.462955, 0.520777 },
    { 0.013183, 0.488207, 0.498610 },
    { 0.010476, 0.513404, 0.476120 },
    { 0.008168, 0.538423, 0.453409 },
    { 0.006285, 0.563068, 0.430647 },
    { 0.004875, 0.587116, 0.408008 },
    { 0.003982, 0.610447, 0.385570 },
    { 0.003636, 0.633011, 0.363352 },
    { 0.003859, 0.654823, 0.341318 },
    { 0.004646, 0.675898, 0.319456 },
    { 0.006011, 0.696120, 0.297869 },
    { 0.007988, 0.715342, 0.276670 },
    { 0.010603, 0.733413, 0.255984 },
    { 0.013870, 0.750186, 0.235943 },
    { 0.017766, 0.765612, 0.216622 },
    { 0.022244, 0.779630, 0.198126 },
    { 0.027273, 0.792104, 0.180623 },
    { 0.032820, 0.802926, 0.164254 },
    { 0.038852, 0.812016, 0.149132 },
    { 0.045328, 0.819391, 0.135281 },
    { 0.052177, 0.825164, 0.122660 },
    { 0.059326, 0.829426, 0.111249 },
    { 0.066716, 0.832274, 0.101010 },
    { 0.074302, 0.833803, 0.091894 },
    { 0.082053, 0.834090, 0.083856 },
    { 0.089942, 0.833289, 0.076769 },
    { 0.097940, 0.831593, 0.070468 },
    { 0.106021, 0.829178, 0.064801 },
    { 0.114161, 0.826207, 0.059632 },
    { 0.122347, 0.822770, 0.054882 },
    { 0.130546, 0.818928, 0.050526 },
    { 0.138702, 0.814774, 0.046523 },
    { 0.146773, 0.810395, 0.042832 },
    { 0.154722, 0.805864, 0.039414 },
    { 0.162535, 0.801238, 0.036226 },
    { 0.170237, 0.796519, 0.033244 },
    { 0.177850, 0.791687, 0.030464 },
    { 0.185391, 0.786728, 0.027881 },
    { 0.192876, 0.781629, 0.025495 },
    { 0.200309, 0.776399, 0.023292 },
    { 0.207690, 0.771055, 0.021255 },
    { 0.215030, 0.765595, 0.019375 },
    { 0.222337, 0.760020, 0.017643 },
    { 0.229620, 0.754329, 0.016051 },
    { 0.236885, 0.748524, 0.014591 },
    { 0.244133, 0.742614, 0.013253 },
    { 0.251363, 0.736606, 0.012031 },
    { 0.258578, 0.730507, 0.010916 },
    { 0.265775, 0.724324, 0.009901 },
    { 0.272958, 0.718062, 0.008980 },
    { 0.280129, 0.711725, 0.008146 },
    { 0.287292, 0.705316, 0.007391 },
    { 0.294450, 0.698842, 0.006708 },
    { 0.301604, 0.692308, 0.006088 },
    { 0.308760, 0.685712, 0.005528 },
    { 0.315914, 0.679063, 0.005022 },
    { 0.323066, 0.672367, 0.004566 },
    { 0.330216, 0.665628, 0.004156 },
    { 0.337363, 0.658848, 0.003788 },
    { 0.344513, 0.652028, 0.003459 },
    { 0.351664, 0.645172, 0.003163 },
    { 0.358814, 0.638287, 0.002899 },
    { 0.365959, 0.631379, 0.002662 },
    { 0.373102, 0.624451, 0.002448 },
    { 0.380244, 0.617502, 0.002254 },
    { 0.387379, 0.610542, 0.002079 },
    { 0.394507, 0.603571, 0.001922 },
    { 0.401626, 0.596592, 0.001782 },
    { 0.408736, 0.589607, 0.001657 },
    { 0.415836, 0.582618, 0.001546 },
    { 0.422921, 0.575631, 0.001448 },
    { 0.429989, 0.568649, 0.001362 },
    { 0.437036, 0.561676, 0.001288 },
    { 0.444062, 0.554714, 0.001224 },
    { 0.451065, 0.547766, 0.001169 },
    { 0.458041, 0.540837, 0.001123 },
    { 0.464986, 0.533930, 0.001084 },
    { 0.471899, 0.527051, 0.001051 },
    { 0.478775, 0.520202, 0.001023 },
    { 0.485612, 0.513389, 0.001000 },
    { 0.492405, 0.506615, 0.000980 },
    { 0.499151, 0.499887, 0.000962 },
    { 0.505845, 0.493211, 0.000944 },
    { 0.512486, 0.486591, 0.000923 },
    { 0.519073, 0.480029, 0.000899 },
    { 0.525600, 0.473527, 0.000872 },
    { 0.532066, 0.467091, 0.000843 },
    { 0.538463, 0.460725, 0.000812 },
    { 0.544787, 0.454434, 0.000779 },
    { 0.551031, 0.448225, 0.000744 },
    { 0.557193, 0.442099, 0.000708 },
    { 0.563269, 0.436058, 0.000673 },
    { 0.569257, 0.430102, 0.000641 },
    { 0.575151, 0.424232, 0.000616 },
    { 0.580953, 0.418447, 0.000601 },
    { 0.586650, 0.412758, 0.000591 },
    { 0.592225, 0.407190, 0.000586 },
    { 0.597658, 0.401762, 0.000580 },
    { 0.602933, 0.396497, 0.000571 },
    { 0.608035, 0.391409, 0.000556 },
    { 0.612977, 0.386486, 0.000537 },
    { 0.617779, 0.381706, 0.000516 },
    { 0.622459, 0.377047, 0.000493 },
    { 0.627037, 0.372491, 0.000472 },
    { 0.631521, 0.368026, 0.000453 },
    { 0.635900, 0.363665, 0.000435 },
    { 0.640156, 0.359428, 0.000416 },
    { 0.644273, 0.355331, 0.000396 },
    { 0.648233, 0.351395, 0.000372 },
    { 0.652028, 0.347628, 0.000344 },
    { 0.655669, 0.344018, 0.000313 },
    { 0.659166, 0.340553, 0.000281 },
    { 0.662528, 0.337221, 0.000251 },
    { 0.665764, 0.334011, 0.000226 },
    { 0.668874, 0.330919, 0.000207 },
    { 0.671859, 0.327947, 0.000194 },
    { 0.674720, 0.325095, 0.000185 },
    { 0.677459, 0.322362, 0.000179 },
    { 0.680079, 0.319747, 0.000174 },
    { 0.682582, 0.317249, 0.000170 },
    { 0.684971, 0.314863, 0.000167 },
    { 0.687250, 0.312586, 0.000164 },
    { 0.689426, 0.310414, 0.000160 },
    { 0.691504, 0.308342, 0.000154 },
    { 0.693490, 0.306366, 0.000145 },
    { 0.695389, 0.304479, 0.000133 },
    { 0.697206, 0.302675, 0.000119 },
    { 0.698944, 0.300950, 0.000106 },
    { 0.700606, 0.299301, 0.000093 },
    { 0.702193, 0.297725, 0.000083 },
    { 0.703709, 0.296217, 0.000074 },
    { 0.705163, 0.294770, 0.000067 },
    { 0.706563, 0.293376, 0.000061 },
    { 0.707918, 0.292027, 0.000055 },
    { 0.709231, 0.290719, 0.000050 },
    { 0.710500, 0.289453, 0.000047 },
    { 0.711724, 0.288232, 0.000044 },
    { 0.712901, 0.287057, 0.000041 },
    { 0.714032, 0.285929, 0.000040 },
    { 0.715117, 0.284845, 0.000038 },
    { 0.716159, 0.283804, 0.000036 },
    { 0.717159, 0.282806, 0.000035 },
    { 0.718116, 0.281850, 0.000034 },
    { 0.719033, 0.280935, 0.000032 },
    { 0.719912, 0.280058, 0.000030 },
    { 0.720753, 0.279219, 0.000028 },
    { 0.721555, 0.278420, 0.000026 },
    { 0.722315, 0.277662, 0.000023 },
    { 0.723032, 0.276948, 0.000020 },
    { 0.723702, 0.276282, 0.000016 },
    { 0.724328, 0.275660, 0.000012 },
    { 0.724914, 0.275078, 0.000007 },
    { 0.725467, 0.274530, 0.000003 },
    { 0.725992, 0.274008, 0.000000 },
    { 0.726495, 0.273505, 0.000000 },
    { 0.726975, 0.273025, 0.000000 },
    { 0.727432, 0.272568, 0.000000 },
    { 0.727864, 0.272136, 0.000000 },
    { 0.728272, 0.271728, 0.000000 },
    { 0.728656, 0.271344, 0.000000 },
    { 0.729020, 0.270980, 0.000000 },
    { 0.729361, 0.270639, 0.000000 },
    { 0.729678, 0.270322, 0.000000 },
    { 0.729969, 0.270031, 0.000000 },
    { 0.730234, 0.269766, 0.000000 },
    { 0.730474, 0.269526, 0.000000 },
    { 0.730693, 0.269307, 0.000000 },
    { 0.730896, 0.269104, 0.000000 },
    { 0.731089, 0.268911, 0.000000 },
    { 0.731280, 0.268720, 0.000000 },
    { 0.731467, 0.268533, 0.000000 },
    { 0.731650, 0.268350, 0.000000 },
    { 0.731826, 0.268174, 0.000000 },
    { 0.731993, 0.268007, 0.000000 },
    { 0.732150, 0.267850, 0.000000 },
    { 0.732300, 0.267700, 0.000000 },
    { 0.732443, 0.267557, 0.000000 },
    { 0.732581, 0.267419, 0.000000 },
    { 0.732719, 0.267281, 0.000000 },
    { 0.732859, 0.267141, 0.000000 },
    { 0.733000, 0.267000, 0.000000 },
    { 0.733142, 0.266858, 0.000000 },
    { 0.733281, 0.266719, 0.000000 },
    { 0.733417, 0.266583, 0.000000 },
    { 0.733551, 0.266449, 0.000000 },
    { 0.733683, 0.266317, 0.000000 },
    { 0.733813, 0.266187, 0.000000 },
    { 0.733936, 0.266064, 0.000000 },
    { 0.734047, 0.265953, 0.000000 },
    { 0.734143, 0.265857, 0.000000 },
    { 0.734221, 0.265779, 0.000000 },
    { 0.734286, 0.265714, 0.000000 },
    { 0.734341, 0.265659, 0.000000 },
    { 0.734390, 0.265610, 0.000000 },
    { 0.734438, 0.265562, 0.000000 },
    { 0.734482, 0.265518, 0.000000 },
    { 0.734523, 0.265477, 0.000000 },
    { 0.734560, 0.265440, 0.000000 },
    { 0.734592, 0.265408, 0.000000 },
    { 0.734621, 0.265379, 0.000000 },
    { 0.734649, 0.265351, 0.000000 },
    { 0.734673, 0.265327, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
    { 0.734690, 0.265310, 0.000000 },
};


/* Standard white point chromaticities. */

#define C     0.310063, 0.316158
#define E     1.0/3.0, 1.0/3.0
#define D50   0.34570, 0.3585
#define D65   0.312713, 0.329016

/* Gamma of nonlinear correction.
   See Charles Poynton's ColorFAQ Item 45 and GammaFAQ Item 6 at
   http://www.inforamp.net/~poynton/ColorFAQ.html
   http://www.inforamp.net/~poynton/GammaFAQ.html
*/

#define GAMMA_REC709    0.      /* Rec. 709 */

static const struct ColorSystem color_systems[] = {
    [NTSCsystem] = {
        0.67,  0.33,  0.21,  0.71,  0.14,  0.08,
        C, GAMMA_REC709
    },
    [EBUsystem] = {
        0.64,  0.33,  0.29,  0.60,  0.15,  0.06,
        D65, GAMMA_REC709
    },
    [SMPTEsystem] = {
        0.630, 0.340, 0.310, 0.595, 0.155, 0.070,
        D65, GAMMA_REC709
    },
    [SMPTE240Msystem] = {
        0.670, 0.330, 0.210, 0.710, 0.150, 0.060,
        D65, GAMMA_REC709
    },
    [APPLEsystem] = {
        0.625, 0.340, 0.280, 0.595, 0.115, 0.070,
        D65, GAMMA_REC709
    },
    [wRGBsystem] = {
        0.7347, 0.2653, 0.1152, 0.8264, 0.1566, 0.0177,
        D50, GAMMA_REC709
    },
    [CIE1931system] = {
        0.7347, 0.2653, 0.2738, 0.7174, 0.1666, 0.0089,
        E, GAMMA_REC709
    },
    [Rec709system] = {
        0.64,  0.33,  0.30,  0.60,  0.15,  0.06,
        D65, GAMMA_REC709
    },
    [Rec2020system] = {
        0.708,  0.292,  0.170,  0.797,  0.131,  0.046,
        D65, GAMMA_REC709
    },
};

/*
static struct ColorSystem CustomSystem = {
    "Custom",
    0.64,  0.33,  0.30,  0.60,  0.15,  0.06,
    D65, GAMMA_REC709
};
*/

static void
uv_to_xy(double   const u,
         double   const v,
         double * const xc,
         double * const yc)
{
/*
    Given 1970 coordinates u, v, determine 1931 chromaticities x, y
*/
    *xc = 3*u / (2*u - 8*v + 4);
    *yc = 2*v / (2*u - 8*v + 4);
}

static void
upvp_to_xy(double   const up,
           double   const vp,
           double * const xc,
           double * const yc)
{
/*
    Given 1976 coordinates u', v', determine 1931 chromaticities x, y
*/
    *xc = 9*up / (6*up - 16*vp + 12);
    *yc = 4*vp / (6*up - 16*vp + 12);
}

static void
xy_to_upvp(double xc,
           double yc,
           double * const up,
           double * const vp)
{
/*
    Given 1931 chromaticities x, y, determine 1976 coordinates u', v'
*/
    *up = 4*xc / (- 2*xc + 12*yc + 3);
    *vp = 9*yc / (- 2*xc + 12*yc + 3);
}

static void
xy_to_uv(double xc,
         double yc,
         double * const u,
         double * const v)
{
/*
    Given 1931 chromaticities x, y, determine 1960 coordinates u, v
*/
    *u = 4*xc / (- 2*xc + 12*yc + 3);
    *v = 6*yc / (- 2*xc + 12*yc + 3);
}

static void
xyz_to_rgb(const double m[3][3],
           double xc, double yc, double zc,
           double * const r, double * const g, double * const b)
{
    *r = m[0][0]*xc + m[0][1]*yc + m[0][2]*zc;
    *g = m[1][0]*xc + m[1][1]*yc + m[1][2]*zc;
    *b = m[2][0]*xc + m[2][1]*yc + m[2][2]*zc;
}

static void invert_matrix3x3(double in[3][3], double out[3][3])
{
    double m00 = in[0][0], m01 = in[0][1], m02 = in[0][2],
           m10 = in[1][0], m11 = in[1][1], m12 = in[1][2],
           m20 = in[2][0], m21 = in[2][1], m22 = in[2][2];
    int i, j;
    double det;

    out[0][0] =  (m11 * m22 - m21 * m12);
    out[0][1] = -(m01 * m22 - m21 * m02);
    out[0][2] =  (m01 * m12 - m11 * m02);
    out[1][0] = -(m10 * m22 - m20 * m12);
    out[1][1] =  (m00 * m22 - m20 * m02);
    out[1][2] = -(m00 * m12 - m10 * m02);
    out[2][0] =  (m10 * m21 - m20 * m11);
    out[2][1] = -(m00 * m21 - m20 * m01);
    out[2][2] =  (m00 * m11 - m10 * m01);

    det = m00 * out[0][0] + m10 * out[0][1] + m20 * out[0][2];
    det = 1.0 / det;

    for (i = 0; i < 3; i++) {
        for (j = 0; j < 3; j++)
            out[i][j] *= det;
    }
}

static void get_rgb2xyz_matrix(struct ColorSystem system, double m[3][3])
{
    double S[3], X[4], Z[4];
    int i;

    X[0] = system.xRed   / system.yRed;
    X[1] = system.xGreen / system.yGreen;
    X[2] = system.xBlue  / system.yBlue;
    X[3] = system.xWhite / system.yWhite;

    Z[0] = (1 - system.xRed   - system.yRed)   / system.yRed;
    Z[1] = (1 - system.xGreen - system.yGreen) / system.yGreen;
    Z[2] = (1 - system.xBlue  - system.yBlue)  / system.yBlue;
    Z[3] = (1 - system.xWhite - system.yWhite) / system.yWhite;

    for (i = 0; i < 3; i++) {
        m[0][i] = X[i];
        m[1][i] = 1;
        m[2][i] = Z[i];
    }

    invert_matrix3x3(m, m);

    for (i = 0; i < 3; i++)
        S[i] = m[i][0] * X[3] + m[i][1] * 1 + m[i][2] * Z[3];

    for (i = 0; i < 3; i++) {
        m[0][i] = S[i] * X[i];
        m[1][i] = S[i] * 1;
        m[2][i] = S[i] * Z[i];
    }
}

static void
rgb_to_xy(double rc,
          double gc,
          double bc,
          double * const x,
          double * const y,
          double * const z,
          const double m[3][3])
{
    double sum;

    *x = m[0][0] * rc + m[0][1] * gc + m[0][2] * bc;
    *y = m[1][0] * rc + m[1][1] * gc + m[1][2] * bc;
    *z = m[2][0] * rc + m[2][1] * gc + m[2][2] * bc;

    sum = *x + *y + *z;
    if (sum == 0)
        sum = 1;
    *x = *x / sum;
    *y = *y / sum;
}

static int
constrain_rgb(double * const r,
              double * const g,
              double * const b)
{
/*----------------------------------------------------------------------------
    If  the  requested RGB shade contains a negative weight for one of
    the primaries, it lies outside the color  gamut  accessible  from
    the  given  triple  of  primaries.  Desaturate it by adding white,
    equal quantities of R, G, and B, enough to make RGB all positive.
-----------------------------------------------------------------------------*/
    double w;

    /* Amount of white needed is w = - min(0, *r, *g, *b) */
    w = (0 < *r) ? 0 : *r;
    w = (w < *g) ? w : *g;
    w = (w < *b) ? w : *b;
    w = - w;

    /* Add just enough white to make r, g, b all positive. */
    if (w > 0) {
        *r += w;  *g += w; *b += w;

        return 1;                     /* Color modified to fit RGB gamut */
    }

    return 0;                         /* Color within RGB gamut */
}

static void
gamma_correct(const struct ColorSystem * const cs,
              double *                   const c)
{
/*----------------------------------------------------------------------------
    Transform linear RGB values to nonlinear RGB values.

    Rec. 709 is ITU-R Recommendation BT. 709 (1990)
    ``Basic Parameter Values for the HDTV Standard for the Studio and for
    International Programme Exchange'', formerly CCIR Rec. 709.

    For details see
       http://www.inforamp.net/~poynton/ColorFAQ.html
       http://www.inforamp.net/~poynton/GammaFAQ.html
-----------------------------------------------------------------------------*/
    double gamma;
    double cc;

    gamma = cs->gamma;

    if (gamma == 0.) {
        /* Rec. 709 gamma correction. */
        cc = 0.018;
        if (*c < cc) {
            *c *= (1.099 * pow(cc, 0.45) - 0.099) / cc;
        } else {
            *c = 1.099 * pow(*c, 0.45) - 0.099;
        }
    } else {
    /* Nonlinear color = (Linear color)^(1/gamma) */
        *c = pow(*c, 1./gamma);
    }
}


static void
gamma_correct_rgb(const struct ColorSystem * const cs,
                  double * const r,
                  double * const g,
                  double * const b)
{
    gamma_correct(cs, r);
    gamma_correct(cs, g);
    gamma_correct(cs, b);
}

/* Sz(X) is the displacement in pixels of a displacement of X normalized
   distance units.  (A normalized distance unit is 1/512 of the smaller
   dimension of the canvas)
*/
#define Sz(x) (((x) * (int)FFMIN(w, h)) / 512)

static void
monochrome_color_location(double waveLength, int w, int h,
                          int cie, int *xP, int *yP)
{
    const int ix = waveLength - 360;
    const double pX = spectral_chromaticity[ix][0];
    const double pY = spectral_chromaticity[ix][1];
    const double pZ = spectral_chromaticity[ix][2];
    const double px = pX / (pX + pY + pZ);
    const double py = pY / (pX + pY + pZ);

    if (cie == LUV) {
        double up, vp;

        xy_to_upvp(px, py, &up, &vp);
        *xP = up * (w - 1);
        *yP = (h - 1) - vp * (h - 1);
    } else if (cie == UCS) {
        double u, v;

        xy_to_uv(px, py, &u, &v);
        *xP = u * (w - 1);
        *yP = (h - 1) - v * (h - 1);
    } else if (cie == XYY) {
        *xP = px * (w - 1);
        *yP = (h - 1) - py * (h - 1);
    } else {
        av_assert0(0);
    }
}

static void
find_tongue(uint16_t* const pixels,
            int       const w,
            int       const linesize,
            int       const row,
            int *     const presentP,
            int *     const leftEdgeP,
            int *     const rightEdgeP)
{
    int i;

    for (i = 0; i < w && pixels[row * linesize + i * 4 + 0] == 0; i++)
        ;

    if (i >= w) {
        *presentP = 0;
    } else {
        int j;
        int const leftEdge = i;

        *presentP = 1;

        for (j = w - 1; j >= leftEdge && pixels[row * linesize + j * 4 + 0] == 0; j--)
            ;

        *rightEdgeP = j;
        *leftEdgeP = leftEdge;
    }
}

static void draw_line(uint16_t *const pixels, int linesize,
                      int x0, int y0, int x1, int y1,
                      int w, int h,
                      const uint16_t *const rgbcolor)
{
    int dx  = FFABS(x1 - x0), sx = x0 < x1 ? 1 : -1;
    int dy  = FFABS(y1 - y0), sy = y0 < y1 ? 1 : -1;
    int err = (dx > dy ? dx : -dy) / 2, e2;

    for (;;) {
        pixels[y0 * linesize + x0 * 4 + 0] = rgbcolor[0];
        pixels[y0 * linesize + x0 * 4 + 1] = rgbcolor[1];
        pixels[y0 * linesize + x0 * 4 + 2] = rgbcolor[2];
        pixels[y0 * linesize + x0 * 4 + 3] = rgbcolor[3];

        if (x0 == x1 && y0 == y1)
            break;

        e2 = err;

        if (e2 >-dx) {
            err -= dy;
            x0 += sx;
        }

        if (e2 < dy) {
            err += dx;
            y0 += sy;
        }
    }
}

static void draw_rline(uint16_t *const pixels, int linesize,
                       int x0, int y0, int x1, int y1,
                       int w, int h)
{
    int dx  = FFABS(x1 - x0), sx = x0 < x1 ? 1 : -1;
    int dy  = FFABS(y1 - y0), sy = y0 < y1 ? 1 : -1;
    int err = (dx > dy ? dx : -dy) / 2, e2;

    for (;;) {
        pixels[y0 * linesize + x0 * 4 + 0] = 65535 - pixels[y0 * linesize + x0 * 4 + 0];
        pixels[y0 * linesize + x0 * 4 + 1] = 65535 - pixels[y0 * linesize + x0 * 4 + 1];
        pixels[y0 * linesize + x0 * 4 + 2] = 65535 - pixels[y0 * linesize + x0 * 4 + 2];
        pixels[y0 * linesize + x0 * 4 + 3] = 65535;

        if (x0 == x1 && y0 == y1)
            break;

        e2 = err;

        if (e2 >-dx) {
            err -= dy;
            x0 += sx;
        }

        if (e2 < dy) {
            err += dx;
            y0 += sy;
        }
    }
}

static void
tongue_outline(uint16_t* const pixels,
               int       const linesize,
               int       const w,
               int       const h,
               uint16_t  const maxval,
               int       const cie)
{
    const uint16_t rgbcolor[4] = { maxval, maxval, maxval, maxval };
    int wavelength;
    int lx, ly;
    int fx, fy;

    for (wavelength = 360; wavelength <= 830; wavelength++) {
        int icx, icy;

        monochrome_color_location(wavelength, w, h, cie,
                                  &icx, &icy);

        if (wavelength > 360)
            draw_line(pixels, linesize, lx, ly, icx, icy, w, h, rgbcolor);
        else {
            fx = icx;
            fy = icy;
        }
        lx = icx;
        ly = icy;
    }
    draw_line(pixels, linesize, lx, ly, fx, fy, w, h, rgbcolor);
}

static void
fill_in_tongue(uint16_t*                  const pixels,
               int                        const linesize,
               int                        const w,
               int                        const h,
               uint16_t                   const maxval,
               const struct ColorSystem * const cs,
               double                     const m[3][3],
               int                        const cie,
               int                        const correct_gamma,
               float                      const contrast)
{
    int y;

    /* Scan the image line by line and  fill  the  tongue  outline
       with the RGB values determined by the color system for the x-y
       co-ordinates within the tongue.
    */

    for (y = 0; y < h; ++y) {
        int  present;  /* There is some tongue on this line */
        int leftEdge; /* x position of leftmost pixel in tongue on this line */
        int rightEdge; /* same, but rightmost */

        find_tongue(pixels, w, linesize, y, &present, &leftEdge, &rightEdge);

        if (present) {
            int x;

            for (x = leftEdge; x <= rightEdge; ++x) {
                double cx, cy, cz, jr, jg, jb, jmax;
                int r, g, b, mx = maxval;

                if (cie == LUV) {
                    double up, vp;
                    up = ((double) x) / (w - 1);
                    vp = 1.0 - ((double) y) / (h - 1);
                    upvp_to_xy(up, vp, &cx, &cy);
                    cz = 1.0 - (cx + cy);
                } else if (cie == UCS) {
                    double u, v;
                    u = ((double) x) / (w - 1);
                    v = 1.0 - ((double) y) / (h - 1);
                    uv_to_xy(u, v, &cx, &cy);
                    cz = 1.0 - (cx + cy);
                } else if (cie == XYY) {
                    cx = ((double) x) / (w - 1);
                    cy = 1.0 - ((double) y) / (h - 1);
                    cz = 1.0 - (cx + cy);
                } else {
                    av_assert0(0);
                }

                xyz_to_rgb(m, cx, cy, cz, &jr, &jg, &jb);

                /* Check whether the requested color  is  within  the
                   gamut  achievable with the given color system.  If
                   not, draw it in a reduced  intensity,  interpolated
                   by desaturation to the closest within-gamut color. */

                if (constrain_rgb(&jr, &jg, &jb))
                    mx *= contrast;

                jmax = FFMAX3(jr, jg, jb);
                if (jmax > 0) {
                    jr = jr / jmax;
                    jg = jg / jmax;
                    jb = jb / jmax;
                }
                /* gamma correct from linear rgb to nonlinear rgb. */
                if (correct_gamma)
                    gamma_correct_rgb(cs, &jr, &jg, &jb);
                r = mx * jr;
                g = mx * jg;
                b = mx * jb;
                pixels[y * linesize + x * 4 + 0] = r;
                pixels[y * linesize + x * 4 + 1] = g;
                pixels[y * linesize + x * 4 + 2] = b;
                pixels[y * linesize + x * 4 + 3] = 65535;
            }
        }
    }
}

static void
plot_white_point(uint16_t*      pixels,
                 int      const linesize,
                 int      const w,
                 int      const h,
                 int      const maxval,
                 int      const color_system,
                 int      const cie)
{
    const struct ColorSystem *cs = &color_systems[color_system];
    int wx, wy;

    if (cie == LUV) {
        double wup, wvp;
        xy_to_upvp(cs->xWhite, cs->yWhite, &wup, &wvp);
        wx = wup;
        wy = wvp;
        wx = (w - 1) * wup;
        wy = (h - 1) - ((int) ((h - 1) * wvp));
    } else if (cie == UCS) {
        double wu, wv;
        xy_to_uv(cs->xWhite, cs->yWhite, &wu, &wv);
        wx = wu;
        wy = wv;
        wx = (w - 1) * wu;
        wy = (h - 1) - ((int) ((h - 1) * wv));
    } else if (cie == XYY) {
        wx = (w - 1) * cs->xWhite;
        wy = (h - 1) - ((int) ((h - 1) * cs->yWhite));
    } else {
        av_assert0(0);
    }

    draw_rline(pixels, linesize,
               wx + Sz(3), wy, wx + Sz(10), wy,
               w, h);
    draw_rline(pixels, linesize,
               wx - Sz(3), wy, wx - Sz(10), wy,
               w, h);
    draw_rline(pixels, linesize,
               wx, wy + Sz(3), wx, wy + Sz(10),
               w, h);
    draw_rline(pixels, linesize,
               wx, wy - Sz(3), wx, wy - Sz(10),
               w, h);
}

static int draw_background(AVFilterContext *ctx)
{
    CiescopeContext *s = ctx->priv;
    const struct ColorSystem *cs = &color_systems[s->color_system];
    AVFilterLink *outlink = ctx->outputs[0];
    int w = s->size;
    int h = s->size;
    uint16_t *pixels;

    if ((s->f = ff_get_video_buffer(outlink, outlink->w, outlink->h)) == NULL)
        return AVERROR(ENOMEM);
    pixels = (uint16_t *)s->f->data[0];

    tongue_outline(pixels, s->f->linesize[0] / 2, w, h, 65535, s->cie);

    fill_in_tongue(pixels, s->f->linesize[0] / 2, w, h, 65535, cs, (const double (*)[3])s->i, s->cie,
                   s->correct_gamma, s->contrast);

    return 0;
}

static void filter_rgb48(AVFilterContext *ctx, AVFrame *in, double *cx, double *cy, int x, int y)
{
    CiescopeContext *s = ctx->priv;
    const uint16_t* src = (const uint16_t*)(in->data[0] + in->linesize[0] * y + x * 6);
    double r = src[0] / 65535.;
    double g = src[1] / 65535.;
    double b = src[2] / 65535.;
    double cz;

    rgb_to_xy(r, g, b, cx, cy, &cz, (const double (*)[3])s->m);
}

static void filter_rgba64(AVFilterContext *ctx, AVFrame *in, double *cx, double *cy, int x, int y)
{
    CiescopeContext *s = ctx->priv;
    const uint16_t* src = (const uint16_t*)(in->data[0] + in->linesize[0] * y + x * 8);
    double r = src[0] / 65535.;
    double g = src[1] / 65535.;
    double b = src[2] / 65535.;
    double cz;

    rgb_to_xy(r, g, b, cx, cy, &cz, (const double (*)[3])s->m);
}

static void filter_rgb24(AVFilterContext *ctx, AVFrame *in, double *cx, double *cy, int x, int y)
{
    CiescopeContext *s = ctx->priv;
    const uint8_t* src = in->data[0] + in->linesize[0] * y + x * 3;
    double r = src[0] / 255.;
    double g = src[1] / 255.;
    double b = src[2] / 255.;
    double cz;

    rgb_to_xy(r, g, b, cx, cy, &cz, (const double (*)[3])s->m);
}

static void filter_rgba(AVFilterContext *ctx, AVFrame *in, double *cx, double *cy, int x, int y)
{
    CiescopeContext *s = ctx->priv;
    const uint8_t* src = in->data[0] + in->linesize[0] * y + x * 4;
    double r = src[0] / 255.;
    double g = src[1] / 255.;
    double b = src[2] / 255.;
    double cz;

    rgb_to_xy(r, g, b, cx, cy, &cz, (const double (*)[3])s->m);
}

static void filter_xyz(AVFilterContext *ctx, AVFrame *in, double *cx, double *cy, int x, int y)
{
    CiescopeContext *s = ctx->priv;
    const uint16_t* src = (uint16_t *)(in->data[0] + in->linesize[0] * y + x * 6);
    double lx = s->log2lin[src[0]];
    double ly = s->log2lin[src[1]];
    double lz = s->log2lin[src[2]];
    double sum = lx + ly + lz;

    if (sum == 0)
        sum = 1;
    *cx = lx / sum;
    *cy = ly / sum;
}

static void plot_gamuts(uint16_t *pixels, int linesize, int w, int h,
                        int cie, int gamuts)
{
    int i;

    for (i = 0; i < NB_CS; i++) {
        const struct ColorSystem *cs = &color_systems[i];
        int rx, ry, gx, gy, bx, by;

        if (!((1 << i) & gamuts))
            continue;
        if (cie == LUV) {
            double wup, wvp;
            xy_to_upvp(cs->xRed, cs->yRed, &wup, &wvp);
            rx = (w - 1) * wup;
            ry = (h - 1) - ((int) ((h - 1) * wvp));
            xy_to_upvp(cs->xGreen, cs->yGreen, &wup, &wvp);
            gx = (w - 1) * wup;
            gy = (h - 1) - ((int) ((h - 1) * wvp));
            xy_to_upvp(cs->xBlue, cs->yBlue, &wup, &wvp);
            bx = (w - 1) * wup;
            by = (h - 1) - ((int) ((h - 1) * wvp));
        } else if (cie == UCS) {
            double wu, wv;
            xy_to_uv(cs->xRed, cs->yRed, &wu, &wv);
            rx = (w - 1) * wu;
            ry = (h - 1) - ((int) ((h - 1) * wv));
            xy_to_uv(cs->xGreen, cs->yGreen, &wu, &wv);
            gx = (w - 1) * wu;
            gy = (h - 1) - ((int) ((h - 1) * wv));
            xy_to_uv(cs->xBlue, cs->yBlue, &wu, &wv);
            bx = (w - 1) * wu;
            by = (h - 1) - ((int) ((h - 1) * wv));
        } else if (cie == XYY) {
            rx = (w - 1) * cs->xRed;
            ry = (h - 1) - ((int) ((h - 1) * cs->yRed));
            gx = (w - 1) * cs->xGreen;
            gy = (h - 1) - ((int) ((h - 1) * cs->yGreen));
            bx = (w - 1) * cs->xBlue;
            by = (h - 1) - ((int) ((h - 1) * cs->yBlue));
        } else {
            av_assert0(0);
        }

        draw_rline(pixels, linesize, rx, ry, gx, gy, w, h);
        draw_rline(pixels, linesize, gx, gy, bx, by, w, h);
        draw_rline(pixels, linesize, bx, by, rx, ry, w, h);
    }
}

static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
    AVFilterContext *ctx  = inlink->dst;
    CiescopeContext *s = ctx->priv;
    AVFilterLink *outlink = ctx->outputs[0];
    int i = s->intensity * 65535;
    int w = outlink->w;
    int h = outlink->h;
    AVFrame *out;
    int ret, x, y;

    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
    if (!out) {
        av_frame_free(&in);
        return AVERROR(ENOMEM);
    }
    out->pts = in->pts;

    if (!s->background) {
        ret = draw_background(ctx);
        if (ret < 0) {
            av_frame_free(&out);
            return ret;
        }
        s->background = 1;
    }
    for (y = 0; y < outlink->h; y++) {
        memset(out->data[0] + y * out->linesize[0], 0, outlink->w * 8);
    }

    for (y = 0; y < in->height; y++) {
        for (x = 0; x < in->width; x++) {
            double cx, cy;
            uint16_t *dst;
            int wx, wy;

            s->filter(ctx, in, &cx, &cy, x, y);

            if (s->cie == LUV) {
                double up, vp;
                xy_to_upvp(cx, cy, &up, &vp);
                cx = up;
                cy = vp;
            } else if (s->cie == UCS) {
                double u, v;
                xy_to_uv(cx, cy, &u, &v);
                cx = u;
                cy = v;
            }

            wx = (w - 1) * cx;
            wy = (h - 1) - ((h - 1) * cy);

            if (wx < 0 || wx >= w ||
                wy < 0 || wy >= h)
                continue;

            dst = (uint16_t *)(out->data[0] + wy * out->linesize[0] + wx * 8 + 0);
            dst[0] = FFMIN(dst[0] + i, 65535);
            dst[1] = FFMIN(dst[1] + i, 65535);
            dst[2] = FFMIN(dst[2] + i, 65535);
            dst[3] = 65535;
        }
    }

    for (y = 0; y < outlink->h; y++) {
        uint16_t *dst = (uint16_t *)(out->data[0] + y * out->linesize[0]);
        const uint16_t *src = (const uint16_t *)(s->f->data[0] + y * s->f->linesize[0]);
        for (x = 0; x < outlink->w; x++) {
            const int xx = x * 4;
            if (dst[xx + 3] == 0) {
                dst[xx + 0] = src[xx + 0];
                dst[xx + 1] = src[xx + 1];
                dst[xx + 2] = src[xx + 2];
                dst[xx + 3] = src[xx + 3];
            }
        }
    }

    if (s->show_white)
        plot_white_point((uint16_t *)out->data[0], out->linesize[0] / 2,
                         outlink->w, outlink->h, 65535,
                         s->color_system, s->cie);

    plot_gamuts((uint16_t *)out->data[0], out->linesize[0] / 2,
                outlink->w, outlink->h,
                s->cie, s->gamuts);

    av_frame_free(&in);
    return ff_filter_frame(outlink, out);
}

static void av_cold uninit(AVFilterContext *ctx)
{
    CiescopeContext *s = ctx->priv;

    av_frame_free(&s->f);
}

static int config_input(AVFilterLink *inlink)
{
    CiescopeContext *s = inlink->dst->priv;
    int i;

    get_rgb2xyz_matrix(color_systems[s->color_system], s->m);
    invert_matrix3x3(s->m, s->i);

    switch (inlink->format) {
    case AV_PIX_FMT_RGB24:
        s->filter = filter_rgb24;
        break;
    case AV_PIX_FMT_RGBA:
        s->filter = filter_rgba;
        break;
    case AV_PIX_FMT_RGB48:
        s->filter = filter_rgb48;
        break;
    case AV_PIX_FMT_RGBA64:
        s->filter = filter_rgba64;
        break;
    case AV_PIX_FMT_XYZ12:
        s->filter = filter_xyz;
        for (i = 0; i < 65536; i++)
            s->log2lin[i] = pow(i / 65535., s->igamma) * 65535.;
        break;
    default:
        av_assert0(0);
    }

    return 0;
}

static const AVFilterPad inputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
        .config_props = config_input,
    },
    { NULL }
};

static const AVFilterPad outputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .config_props = config_output,
    },
    { NULL }
};

AVFilter ff_vf_ciescope = {
    .name          = "ciescope",
    .description   = NULL_IF_CONFIG_SMALL("Video CIE scope."),
    .priv_size     = sizeof(CiescopeContext),
    .priv_class    = &ciescope_class,
    .query_formats = query_formats,
    .uninit        = uninit,
    .inputs        = inputs,
    .outputs       = outputs,
};