/*
 * Copyright 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <gtest/gtest.h>
#include <gmock/gmock.h>

#include "ultrahdr/gainmapmath.h"

namespace ultrahdr {

class GainMapMathTest : public testing::Test {
 public:
  GainMapMathTest();
  ~GainMapMathTest();

  float ComparisonEpsilon() { return 1e-4f; }
  float LuminanceEpsilon() { return 1e-2f; }
  float YuvConversionEpsilon() { return 1.0f / (255.0f * 2.0f); }

  Color Yuv420(uint8_t y, uint8_t u, uint8_t v) {
    return {{{static_cast<float>(y) * (1 / 255.0f), static_cast<float>(u - 128) * (1 / 255.0f),
              static_cast<float>(v - 128) * (1 / 255.0f)}}};
  }

  Color P010(uint16_t y, uint16_t u, uint16_t v) {
    return {{{static_cast<float>(y - 64) * (1 / 876.0f),
              static_cast<float>(u - 64) * (1 / 896.0f) - 0.5f,
              static_cast<float>(v - 64) * (1 / 896.0f) - 0.5f}}};
  }

  // Using int16_t allows for testing fixed-point implementations.
  struct Pixel {
    int16_t y;
    int16_t u;
    int16_t v;
  };

  Pixel getYuv420Pixel_uint(uhdr_raw_image_t* image, size_t x, size_t y) {
    uint8_t* luma_data = reinterpret_cast<uint8_t*>(image->planes[UHDR_PLANE_Y]);
    size_t luma_stride = image->stride[UHDR_PLANE_Y];
    uint8_t* cb_data = reinterpret_cast<uint8_t*>(image->planes[UHDR_PLANE_U]);
    size_t cb_stride = image->stride[UHDR_PLANE_U];
    uint8_t* cr_data = reinterpret_cast<uint8_t*>(image->planes[UHDR_PLANE_V]);
    size_t cr_stride = image->stride[UHDR_PLANE_V];

    size_t pixel_y_idx = x + y * luma_stride;
    size_t pixel_cb_idx = x / 2 + (y / 2) * cb_stride;
    size_t pixel_cr_idx = x / 2 + (y / 2) * cr_stride;

    uint8_t y_uint = luma_data[pixel_y_idx];
    uint8_t u_uint = cb_data[pixel_cb_idx];
    uint8_t v_uint = cr_data[pixel_cr_idx];

    return {y_uint, u_uint, v_uint};
  }

  float Map(uint8_t e) { return static_cast<float>(e) / 255.0f; }

  Color ColorMin(Color e1, Color e2) {
    return {{{fminf(e1.r, e2.r), fminf(e1.g, e2.g), fminf(e1.b, e2.b)}}};
  }

  Color ColorMax(Color e1, Color e2) {
    return {{{fmaxf(e1.r, e2.r), fmaxf(e1.g, e2.g), fmaxf(e1.b, e2.b)}}};
  }

  Color RgbBlack() { return {{{0.0f, 0.0f, 0.0f}}}; }
  Color RgbWhite() { return {{{1.0f, 1.0f, 1.0f}}}; }

  Color RgbRed() { return {{{1.0f, 0.0f, 0.0f}}}; }
  Color RgbGreen() { return {{{0.0f, 1.0f, 0.0f}}}; }
  Color RgbBlue() { return {{{0.0f, 0.0f, 1.0f}}}; }

  Color YuvBlack() { return {{{0.0f, 0.0f, 0.0f}}}; }
  Color YuvWhite() { return {{{1.0f, 0.0f, 0.0f}}}; }

  Color SrgbYuvRed() { return {{{0.2126f, -0.11457f, 0.5f}}}; }
  Color SrgbYuvGreen() { return {{{0.7152f, -0.38543f, -0.45415f}}}; }
  Color SrgbYuvBlue() { return {{{0.0722f, 0.5f, -0.04585f}}}; }

  Color P3YuvRed() { return {{{0.299f, -0.16874f, 0.5f}}}; }
  Color P3YuvGreen() { return {{{0.587f, -0.33126f, -0.41869f}}}; }
  Color P3YuvBlue() { return {{{0.114f, 0.5f, -0.08131f}}}; }

  Color Bt2100YuvRed() { return {{{0.2627f, -0.13963f, 0.5f}}}; }
  Color Bt2100YuvGreen() { return {{{0.6780f, -0.36037f, -0.45979f}}}; }
  Color Bt2100YuvBlue() { return {{{0.0593f, 0.5f, -0.04021f}}}; }

  //////////////////////////////////////////////////////////////////////////////
  // Reference values for when using fixed-point arithmetic.

  Pixel RgbBlackPixel() { return {0, 0, 0}; }
  Pixel RgbWhitePixel() { return {255, 255, 255}; }

  Pixel RgbRedPixel() { return {255, 0, 0}; }
  Pixel RgbGreenPixel() { return {0, 255, 0}; }
  Pixel RgbBluePixel() { return {0, 0, 255}; }

  Pixel YuvBlackPixel() { return {0, 0, 0}; }
  Pixel YuvWhitePixel() { return {255, 0, 0}; }

  Pixel SrgbYuvRedPixel() { return {54, -29, 128}; }
  Pixel SrgbYuvGreenPixel() { return {182, -98, -116}; }
  Pixel SrgbYuvBluePixel() { return {18, 128, -12}; }

  Pixel P3YuvRedPixel() { return {76, -43, 128}; }
  Pixel P3YuvGreenPixel() { return {150, -84, -107}; }
  Pixel P3YuvBluePixel() { return {29, 128, -21}; }

  Pixel Bt2100YuvRedPixel() { return {67, -36, 128}; }
  Pixel Bt2100YuvGreenPixel() { return {173, -92, -117}; }
  Pixel Bt2100YuvBluePixel() { return {15, 128, -10}; }

  float SrgbYuvToLuminance(Color yuv_gamma, LuminanceFn luminanceFn) {
    Color rgb_gamma = srgbYuvToRgb(yuv_gamma);
    Color rgb = srgbInvOetf(rgb_gamma);
    float luminance_scaled = luminanceFn(rgb);
    return luminance_scaled * kSdrWhiteNits;
  }

  float P3YuvToLuminance(Color yuv_gamma, LuminanceFn luminanceFn) {
    Color rgb_gamma = p3YuvToRgb(yuv_gamma);
    Color rgb = srgbInvOetf(rgb_gamma);
    float luminance_scaled = luminanceFn(rgb);
    return luminance_scaled * kSdrWhiteNits;
  }

  float Bt2100YuvToLuminance(Color yuv_gamma, ColorTransformFn hdrInvOetf,
                             ColorTransformFn gamutConversionFn, LuminanceFn luminanceFn,
                             float scale_factor) {
    Color rgb_gamma = bt2100YuvToRgb(yuv_gamma);
    Color rgb = hdrInvOetf(rgb_gamma);
    rgb = gamutConversionFn(rgb);
    float luminance_scaled = luminanceFn(rgb);
    return luminance_scaled * scale_factor;
  }

  Color Recover(Color yuv_gamma, float gain, uhdr_gainmap_metadata_ext_t* metadata) {
    Color rgb_gamma = srgbYuvToRgb(yuv_gamma);
    Color rgb = srgbInvOetf(rgb_gamma);
    return applyGain(rgb, gain, metadata);
  }

  uhdr_raw_image_t Yuv420Image() {
    static uint8_t pixels[] = {
        // Y
        0x00,
        0x10,
        0x20,
        0x30,
        0x01,
        0x11,
        0x21,
        0x31,
        0x02,
        0x12,
        0x22,
        0x32,
        0x03,
        0x13,
        0x23,
        0x33,
        // U
        0xA0,
        0xA1,
        0xA2,
        0xA3,
        // V
        0xB0,
        0xB1,
        0xB2,
        0xB3,
    };
    uhdr_raw_image_t img;
    img.cg = UHDR_CG_BT_709;
    img.ct = UHDR_CT_SRGB;
    img.range = UHDR_CR_FULL_RANGE;
    img.fmt = UHDR_IMG_FMT_12bppYCbCr420;
    img.w = 4;
    img.h = 4;
    img.planes[UHDR_PLANE_Y] = pixels;
    img.planes[UHDR_PLANE_U] = pixels + 16;
    img.planes[UHDR_PLANE_V] = pixels + 16 + 4;
    img.stride[UHDR_PLANE_Y] = 4;
    img.stride[UHDR_PLANE_U] = 2;
    img.stride[UHDR_PLANE_V] = 2;
    return img;
  }

  uhdr_raw_image_t Yuv420Image32x4() {
    // clang-format off
    static uint8_t pixels[] = {
    // Y
    0x0, 0x10, 0x20, 0x30, 0x1, 0x11, 0x21, 0x31, 0x2, 0x12, 0x22, 0x32, 0x3, 0x13, 0x23, 0x33,
    0x4, 0x14, 0x24, 0x34, 0x5, 0x15, 0x25, 0x35, 0x6, 0x16, 0x26, 0x36, 0x7, 0x17, 0x27, 0x37,
    0x8, 0x18, 0x28, 0x38, 0x9, 0x19, 0x29, 0x39, 0xa, 0x1a, 0x2a, 0x3a, 0xb, 0x1b, 0x2b, 0x3b,
    0xc, 0x1c, 0x2c, 0x3c, 0xd, 0x1d, 0x2d, 0x3d, 0xe, 0x1e, 0x2e, 0x3e, 0xf, 0x1f, 0x2f, 0x3f,
    0x10, 0x20, 0x30, 0x40, 0x11, 0x21, 0x31, 0x41, 0x12, 0x22, 0x32, 0x42, 0x13, 0x23, 0x33, 0x43,
    0x14, 0x24, 0x34, 0x44, 0x15, 0x25, 0x35, 0x45, 0x16, 0x26, 0x36, 0x46, 0x17, 0x27, 0x37, 0x47,
    0x18, 0x28, 0x38, 0x48, 0x19, 0x29, 0x39, 0x49, 0x1a, 0x2a, 0x3a, 0x4a, 0x1b, 0x2b, 0x3b, 0x4b,
    0x1c, 0x2c, 0x3c, 0x4c, 0x1d, 0x2d, 0x3d, 0x4d, 0x1e, 0x2e, 0x3e, 0x4e, 0x1f, 0x2f, 0x3f, 0x4f,
    // U
    0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF,
    0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBB, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF,
    // V
    0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCC, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF,
    0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDD, 0xDD, 0xDC, 0xDD, 0xDE, 0xDF,
    };
    // clang-format on
    uhdr_raw_image_t img;
    img.cg = UHDR_CG_BT_709;
    img.ct = UHDR_CT_SRGB;
    img.range = UHDR_CR_FULL_RANGE;
    img.fmt = UHDR_IMG_FMT_12bppYCbCr420;
    img.w = 32;
    img.h = 4;
    img.planes[UHDR_PLANE_Y] = pixels;
    img.planes[UHDR_PLANE_U] = pixels + 128;
    img.planes[UHDR_PLANE_V] = pixels + 128 + 32;
    img.stride[UHDR_PLANE_Y] = 32;
    img.stride[UHDR_PLANE_U] = 16;
    img.stride[UHDR_PLANE_V] = 16;
    return img;
  }

  Color (*Yuv420Colors())[4] {
    static Color colors[4][4] = {
        {
            Yuv420(0x00, 0xA0, 0xB0),
            Yuv420(0x10, 0xA0, 0xB0),
            Yuv420(0x20, 0xA1, 0xB1),
            Yuv420(0x30, 0xA1, 0xB1),
        },
        {
            Yuv420(0x01, 0xA0, 0xB0),
            Yuv420(0x11, 0xA0, 0xB0),
            Yuv420(0x21, 0xA1, 0xB1),
            Yuv420(0x31, 0xA1, 0xB1),
        },
        {
            Yuv420(0x02, 0xA2, 0xB2),
            Yuv420(0x12, 0xA2, 0xB2),
            Yuv420(0x22, 0xA3, 0xB3),
            Yuv420(0x32, 0xA3, 0xB3),
        },
        {
            Yuv420(0x03, 0xA2, 0xB2),
            Yuv420(0x13, 0xA2, 0xB2),
            Yuv420(0x23, 0xA3, 0xB3),
            Yuv420(0x33, 0xA3, 0xB3),
        },
    };
    return colors;
  }

  uhdr_raw_image_t P010Image() {
    static uint16_t pixels[] = {
        // Y
        0x00 << 6,
        0x10 << 6,
        0x20 << 6,
        0x30 << 6,
        0x01 << 6,
        0x11 << 6,
        0x21 << 6,
        0x31 << 6,
        0x02 << 6,
        0x12 << 6,
        0x22 << 6,
        0x32 << 6,
        0x03 << 6,
        0x13 << 6,
        0x23 << 6,
        0x33 << 6,
        // UV
        0xA0 << 6,
        0xB0 << 6,
        0xA1 << 6,
        0xB1 << 6,
        0xA2 << 6,
        0xB2 << 6,
        0xA3 << 6,
        0xB3 << 6,
    };
    uhdr_raw_image_t img;
    img.cg = UHDR_CG_BT_709;
    img.ct = UHDR_CT_HLG;
    img.range = UHDR_CR_LIMITED_RANGE;
    img.fmt = UHDR_IMG_FMT_24bppYCbCrP010;
    img.w = 4;
    img.h = 4;
    img.planes[UHDR_PLANE_Y] = pixels;
    img.planes[UHDR_PLANE_UV] = pixels + 16;
    img.planes[UHDR_PLANE_V] = nullptr;
    img.stride[UHDR_PLANE_Y] = 4;
    img.stride[UHDR_PLANE_UV] = 4;
    img.stride[UHDR_PLANE_V] = 0;
    return img;
  }

  Color (*P010Colors())[4] {
    static Color colors[4][4] = {
        {
            P010(0x00, 0xA0, 0xB0),
            P010(0x10, 0xA0, 0xB0),
            P010(0x20, 0xA1, 0xB1),
            P010(0x30, 0xA1, 0xB1),
        },
        {
            P010(0x01, 0xA0, 0xB0),
            P010(0x11, 0xA0, 0xB0),
            P010(0x21, 0xA1, 0xB1),
            P010(0x31, 0xA1, 0xB1),
        },
        {
            P010(0x02, 0xA2, 0xB2),
            P010(0x12, 0xA2, 0xB2),
            P010(0x22, 0xA3, 0xB3),
            P010(0x32, 0xA3, 0xB3),
        },
        {
            P010(0x03, 0xA2, 0xB2),
            P010(0x13, 0xA2, 0xB2),
            P010(0x23, 0xA3, 0xB3),
            P010(0x33, 0xA3, 0xB3),
        },
    };
    return colors;
  }

  uhdr_raw_image_t MapImage() {
    static uint8_t pixels[] = {
        0x00, 0x10, 0x20, 0x30, 0x01, 0x11, 0x21, 0x31,
        0x02, 0x12, 0x22, 0x32, 0x03, 0x13, 0x23, 0x33,
    };

    uhdr_raw_image_t img;
    img.cg = UHDR_CG_UNSPECIFIED;
    img.ct = UHDR_CT_UNSPECIFIED;
    img.range = UHDR_CR_UNSPECIFIED;
    img.fmt = UHDR_IMG_FMT_8bppYCbCr400;
    img.w = 4;
    img.h = 4;
    img.planes[UHDR_PLANE_Y] = pixels;
    img.planes[UHDR_PLANE_U] = nullptr;
    img.planes[UHDR_PLANE_V] = nullptr;
    img.stride[UHDR_PLANE_Y] = 4;
    img.stride[UHDR_PLANE_U] = 0;
    img.stride[UHDR_PLANE_V] = 0;
    return img;
  }

  float (*MapValues())[4] {
    static float values[4][4] = {
        {
            Map(0x00),
            Map(0x10),
            Map(0x20),
            Map(0x30),
        },
        {
            Map(0x01),
            Map(0x11),
            Map(0x21),
            Map(0x31),
        },
        {
            Map(0x02),
            Map(0x12),
            Map(0x22),
            Map(0x32),
        },
        {
            Map(0x03),
            Map(0x13),
            Map(0x23),
            Map(0x33),
        },
    };
    return values;
  }

 protected:
  virtual void SetUp();
  virtual void TearDown();
};

GainMapMathTest::GainMapMathTest() {}
GainMapMathTest::~GainMapMathTest() {}

void GainMapMathTest::SetUp() {}
void GainMapMathTest::TearDown() {}

#define EXPECT_RGB_EQ(e1, e2)      \
  EXPECT_FLOAT_EQ((e1).r, (e2).r); \
  EXPECT_FLOAT_EQ((e1).g, (e2).g); \
  EXPECT_FLOAT_EQ((e1).b, (e2).b)

#define EXPECT_RGB_NEAR(e1, e2)                     \
  EXPECT_NEAR((e1).r, (e2).r, ComparisonEpsilon()); \
  EXPECT_NEAR((e1).g, (e2).g, ComparisonEpsilon()); \
  EXPECT_NEAR((e1).b, (e2).b, ComparisonEpsilon())

#define EXPECT_RGB_CLOSE(e1, e2)                            \
  EXPECT_NEAR((e1).r, (e2).r, ComparisonEpsilon() * 10.0f); \
  EXPECT_NEAR((e1).g, (e2).g, ComparisonEpsilon() * 10.0f); \
  EXPECT_NEAR((e1).b, (e2).b, ComparisonEpsilon() * 10.0f)

#define EXPECT_YUV_EQ(e1, e2)      \
  EXPECT_FLOAT_EQ((e1).y, (e2).y); \
  EXPECT_FLOAT_EQ((e1).u, (e2).u); \
  EXPECT_FLOAT_EQ((e1).v, (e2).v)

#define EXPECT_YUV_NEAR(e1, e2)                     \
  EXPECT_NEAR((e1).y, (e2).y, ComparisonEpsilon()); \
  EXPECT_NEAR((e1).u, (e2).u, ComparisonEpsilon()); \
  EXPECT_NEAR((e1).v, (e2).v, ComparisonEpsilon())

// Due to -ffp-contract=fast being enabled by default with GCC, allow some
// margin when comparing fused and unfused floating-point operations.
#define EXPECT_YUV_BETWEEN(e, min, max)                                           \
  EXPECT_THAT((e).y, testing::AllOf(testing::Ge((min).y - ComparisonEpsilon()),   \
                                    testing::Le((max).y + ComparisonEpsilon()))); \
  EXPECT_THAT((e).u, testing::AllOf(testing::Ge((min).u - ComparisonEpsilon()),   \
                                    testing::Le((max).u + ComparisonEpsilon()))); \
  EXPECT_THAT((e).v, testing::AllOf(testing::Ge((min).v - ComparisonEpsilon()),   \
                                    testing::Le((max).v + ComparisonEpsilon())))

// TODO: a bunch of these tests can be parameterized.

TEST_F(GainMapMathTest, ColorConstruct) {
  Color e1 = {{{0.1f, 0.2f, 0.3f}}};

  EXPECT_FLOAT_EQ(e1.r, 0.1f);
  EXPECT_FLOAT_EQ(e1.g, 0.2f);
  EXPECT_FLOAT_EQ(e1.b, 0.3f);

  EXPECT_FLOAT_EQ(e1.y, 0.1f);
  EXPECT_FLOAT_EQ(e1.u, 0.2f);
  EXPECT_FLOAT_EQ(e1.v, 0.3f);
}

TEST_F(GainMapMathTest, ColorAddColor) {
  Color e1 = {{{0.1f, 0.2f, 0.3f}}};

  Color e2 = e1 + e1;
  EXPECT_FLOAT_EQ(e2.r, e1.r * 2.0f);
  EXPECT_FLOAT_EQ(e2.g, e1.g * 2.0f);
  EXPECT_FLOAT_EQ(e2.b, e1.b * 2.0f);

  e2 += e1;
  EXPECT_FLOAT_EQ(e2.r, e1.r * 3.0f);
  EXPECT_FLOAT_EQ(e2.g, e1.g * 3.0f);
  EXPECT_FLOAT_EQ(e2.b, e1.b * 3.0f);
}

TEST_F(GainMapMathTest, ColorAddFloat) {
  Color e1 = {{{0.1f, 0.2f, 0.3f}}};

  Color e2 = e1 + 0.1f;
  EXPECT_FLOAT_EQ(e2.r, e1.r + 0.1f);
  EXPECT_FLOAT_EQ(e2.g, e1.g + 0.1f);
  EXPECT_FLOAT_EQ(e2.b, e1.b + 0.1f);

  e2 += 0.1f;
  EXPECT_FLOAT_EQ(e2.r, e1.r + 0.2f);
  EXPECT_FLOAT_EQ(e2.g, e1.g + 0.2f);
  EXPECT_FLOAT_EQ(e2.b, e1.b + 0.2f);
}

TEST_F(GainMapMathTest, ColorSubtractColor) {
  Color e1 = {{{0.1f, 0.2f, 0.3f}}};

  Color e2 = e1 - e1;
  EXPECT_FLOAT_EQ(e2.r, 0.0f);
  EXPECT_FLOAT_EQ(e2.g, 0.0f);
  EXPECT_FLOAT_EQ(e2.b, 0.0f);

  e2 -= e1;
  EXPECT_FLOAT_EQ(e2.r, -e1.r);
  EXPECT_FLOAT_EQ(e2.g, -e1.g);
  EXPECT_FLOAT_EQ(e2.b, -e1.b);
}

TEST_F(GainMapMathTest, ColorSubtractFloat) {
  Color e1 = {{{0.1f, 0.2f, 0.3f}}};

  Color e2 = e1 - 0.1f;
  EXPECT_FLOAT_EQ(e2.r, e1.r - 0.1f);
  EXPECT_FLOAT_EQ(e2.g, e1.g - 0.1f);
  EXPECT_FLOAT_EQ(e2.b, e1.b - 0.1f);

  e2 -= 0.1f;
  EXPECT_FLOAT_EQ(e2.r, e1.r - 0.2f);
  EXPECT_FLOAT_EQ(e2.g, e1.g - 0.2f);
  EXPECT_FLOAT_EQ(e2.b, e1.b - 0.2f);
}

TEST_F(GainMapMathTest, ColorMultiplyFloat) {
  Color e1 = {{{0.1f, 0.2f, 0.3f}}};

  Color e2 = e1 * 2.0f;
  EXPECT_FLOAT_EQ(e2.r, e1.r * 2.0f);
  EXPECT_FLOAT_EQ(e2.g, e1.g * 2.0f);
  EXPECT_FLOAT_EQ(e2.b, e1.b * 2.0f);

  e2 *= 2.0f;
  EXPECT_FLOAT_EQ(e2.r, e1.r * 4.0f);
  EXPECT_FLOAT_EQ(e2.g, e1.g * 4.0f);
  EXPECT_FLOAT_EQ(e2.b, e1.b * 4.0f);
}

TEST_F(GainMapMathTest, ColorDivideFloat) {
  Color e1 = {{{0.1f, 0.2f, 0.3f}}};

  Color e2 = e1 / 2.0f;
  EXPECT_FLOAT_EQ(e2.r, e1.r / 2.0f);
  EXPECT_FLOAT_EQ(e2.g, e1.g / 2.0f);
  EXPECT_FLOAT_EQ(e2.b, e1.b / 2.0f);

  e2 /= 2.0f;
  EXPECT_FLOAT_EQ(e2.r, e1.r / 4.0f);
  EXPECT_FLOAT_EQ(e2.g, e1.g / 4.0f);
  EXPECT_FLOAT_EQ(e2.b, e1.b / 4.0f);
}

TEST_F(GainMapMathTest, SrgbLuminance) {
  EXPECT_FLOAT_EQ(srgbLuminance(RgbBlack()), 0.0f);
  EXPECT_FLOAT_EQ(srgbLuminance(RgbWhite()), 1.0f);
  EXPECT_FLOAT_EQ(srgbLuminance(RgbRed()), 0.2126f);
  EXPECT_FLOAT_EQ(srgbLuminance(RgbGreen()), 0.7152f);
  EXPECT_FLOAT_EQ(srgbLuminance(RgbBlue()), 0.0722f);
}

TEST_F(GainMapMathTest, SrgbYuvToRgb) {
  Color rgb_black = srgbYuvToRgb(YuvBlack());
  EXPECT_RGB_NEAR(rgb_black, RgbBlack());

  Color rgb_white = srgbYuvToRgb(YuvWhite());
  EXPECT_RGB_NEAR(rgb_white, RgbWhite());

  Color rgb_r = srgbYuvToRgb(SrgbYuvRed());
  EXPECT_RGB_NEAR(rgb_r, RgbRed());

  Color rgb_g = srgbYuvToRgb(SrgbYuvGreen());
  EXPECT_RGB_NEAR(rgb_g, RgbGreen());

  Color rgb_b = srgbYuvToRgb(SrgbYuvBlue());
  EXPECT_RGB_NEAR(rgb_b, RgbBlue());
}

TEST_F(GainMapMathTest, SrgbRgbToYuv) {
  Color yuv_black = srgbRgbToYuv(RgbBlack());
  EXPECT_YUV_NEAR(yuv_black, YuvBlack());

  Color yuv_white = srgbRgbToYuv(RgbWhite());
  EXPECT_YUV_NEAR(yuv_white, YuvWhite());

  Color yuv_r = srgbRgbToYuv(RgbRed());
  EXPECT_YUV_NEAR(yuv_r, SrgbYuvRed());

  Color yuv_g = srgbRgbToYuv(RgbGreen());
  EXPECT_YUV_NEAR(yuv_g, SrgbYuvGreen());

  Color yuv_b = srgbRgbToYuv(RgbBlue());
  EXPECT_YUV_NEAR(yuv_b, SrgbYuvBlue());
}

TEST_F(GainMapMathTest, SrgbRgbYuvRoundtrip) {
  Color rgb_black = srgbYuvToRgb(srgbRgbToYuv(RgbBlack()));
  EXPECT_RGB_NEAR(rgb_black, RgbBlack());

  Color rgb_white = srgbYuvToRgb(srgbRgbToYuv(RgbWhite()));
  EXPECT_RGB_NEAR(rgb_white, RgbWhite());

  Color rgb_r = srgbYuvToRgb(srgbRgbToYuv(RgbRed()));
  EXPECT_RGB_NEAR(rgb_r, RgbRed());

  Color rgb_g = srgbYuvToRgb(srgbRgbToYuv(RgbGreen()));
  EXPECT_RGB_NEAR(rgb_g, RgbGreen());

  Color rgb_b = srgbYuvToRgb(srgbRgbToYuv(RgbBlue()));
  EXPECT_RGB_NEAR(rgb_b, RgbBlue());
}

TEST_F(GainMapMathTest, SrgbTransferFunction) {
  EXPECT_FLOAT_EQ(srgbInvOetf(0.0f), 0.0f);
  EXPECT_NEAR(srgbInvOetf(0.02f), 0.00154f, ComparisonEpsilon());
  EXPECT_NEAR(srgbInvOetf(0.04045f), 0.00313f, ComparisonEpsilon());
  EXPECT_NEAR(srgbInvOetf(0.5f), 0.21404f, ComparisonEpsilon());
  EXPECT_FLOAT_EQ(srgbInvOetf(1.0f), 1.0f);
}

TEST_F(GainMapMathTest, P3Luminance) {
  EXPECT_FLOAT_EQ(p3Luminance(RgbBlack()), 0.0f);
  EXPECT_FLOAT_EQ(p3Luminance(RgbWhite()), 1.0f);
  EXPECT_FLOAT_EQ(p3Luminance(RgbRed()), 0.20949f);
  EXPECT_FLOAT_EQ(p3Luminance(RgbGreen()), 0.72160f);
  EXPECT_FLOAT_EQ(p3Luminance(RgbBlue()), 0.06891f);
}

TEST_F(GainMapMathTest, P3YuvToRgb) {
  Color rgb_black = p3YuvToRgb(YuvBlack());
  EXPECT_RGB_NEAR(rgb_black, RgbBlack());

  Color rgb_white = p3YuvToRgb(YuvWhite());
  EXPECT_RGB_NEAR(rgb_white, RgbWhite());

  Color rgb_r = p3YuvToRgb(P3YuvRed());
  EXPECT_RGB_NEAR(rgb_r, RgbRed());

  Color rgb_g = p3YuvToRgb(P3YuvGreen());
  EXPECT_RGB_NEAR(rgb_g, RgbGreen());

  Color rgb_b = p3YuvToRgb(P3YuvBlue());
  EXPECT_RGB_NEAR(rgb_b, RgbBlue());
}

TEST_F(GainMapMathTest, P3RgbToYuv) {
  Color yuv_black = p3RgbToYuv(RgbBlack());
  EXPECT_YUV_NEAR(yuv_black, YuvBlack());

  Color yuv_white = p3RgbToYuv(RgbWhite());
  EXPECT_YUV_NEAR(yuv_white, YuvWhite());

  Color yuv_r = p3RgbToYuv(RgbRed());
  EXPECT_YUV_NEAR(yuv_r, P3YuvRed());

  Color yuv_g = p3RgbToYuv(RgbGreen());
  EXPECT_YUV_NEAR(yuv_g, P3YuvGreen());

  Color yuv_b = p3RgbToYuv(RgbBlue());
  EXPECT_YUV_NEAR(yuv_b, P3YuvBlue());
}

TEST_F(GainMapMathTest, P3RgbYuvRoundtrip) {
  Color rgb_black = p3YuvToRgb(p3RgbToYuv(RgbBlack()));
  EXPECT_RGB_NEAR(rgb_black, RgbBlack());

  Color rgb_white = p3YuvToRgb(p3RgbToYuv(RgbWhite()));
  EXPECT_RGB_NEAR(rgb_white, RgbWhite());

  Color rgb_r = p3YuvToRgb(p3RgbToYuv(RgbRed()));
  EXPECT_RGB_NEAR(rgb_r, RgbRed());

  Color rgb_g = p3YuvToRgb(p3RgbToYuv(RgbGreen()));
  EXPECT_RGB_NEAR(rgb_g, RgbGreen());

  Color rgb_b = p3YuvToRgb(p3RgbToYuv(RgbBlue()));
  EXPECT_RGB_NEAR(rgb_b, RgbBlue());
}
TEST_F(GainMapMathTest, Bt2100Luminance) {
  EXPECT_FLOAT_EQ(bt2100Luminance(RgbBlack()), 0.0f);
  EXPECT_FLOAT_EQ(bt2100Luminance(RgbWhite()), 1.0f);
  EXPECT_FLOAT_EQ(bt2100Luminance(RgbRed()), 0.2627f);
  EXPECT_FLOAT_EQ(bt2100Luminance(RgbGreen()), 0.6780f);
  EXPECT_FLOAT_EQ(bt2100Luminance(RgbBlue()), 0.0593f);
}

TEST_F(GainMapMathTest, Bt2100YuvToRgb) {
  Color rgb_black = bt2100YuvToRgb(YuvBlack());
  EXPECT_RGB_NEAR(rgb_black, RgbBlack());

  Color rgb_white = bt2100YuvToRgb(YuvWhite());
  EXPECT_RGB_NEAR(rgb_white, RgbWhite());

  Color rgb_r = bt2100YuvToRgb(Bt2100YuvRed());
  EXPECT_RGB_NEAR(rgb_r, RgbRed());

  Color rgb_g = bt2100YuvToRgb(Bt2100YuvGreen());
  EXPECT_RGB_NEAR(rgb_g, RgbGreen());

  Color rgb_b = bt2100YuvToRgb(Bt2100YuvBlue());
  EXPECT_RGB_NEAR(rgb_b, RgbBlue());
}

TEST_F(GainMapMathTest, Bt2100RgbToYuv) {
  Color yuv_black = bt2100RgbToYuv(RgbBlack());
  EXPECT_YUV_NEAR(yuv_black, YuvBlack());

  Color yuv_white = bt2100RgbToYuv(RgbWhite());
  EXPECT_YUV_NEAR(yuv_white, YuvWhite());

  Color yuv_r = bt2100RgbToYuv(RgbRed());
  EXPECT_YUV_NEAR(yuv_r, Bt2100YuvRed());

  Color yuv_g = bt2100RgbToYuv(RgbGreen());
  EXPECT_YUV_NEAR(yuv_g, Bt2100YuvGreen());

  Color yuv_b = bt2100RgbToYuv(RgbBlue());
  EXPECT_YUV_NEAR(yuv_b, Bt2100YuvBlue());
}

TEST_F(GainMapMathTest, Bt2100RgbYuvRoundtrip) {
  Color rgb_black = bt2100YuvToRgb(bt2100RgbToYuv(RgbBlack()));
  EXPECT_RGB_NEAR(rgb_black, RgbBlack());

  Color rgb_white = bt2100YuvToRgb(bt2100RgbToYuv(RgbWhite()));
  EXPECT_RGB_NEAR(rgb_white, RgbWhite());

  Color rgb_r = bt2100YuvToRgb(bt2100RgbToYuv(RgbRed()));
  EXPECT_RGB_NEAR(rgb_r, RgbRed());

  Color rgb_g = bt2100YuvToRgb(bt2100RgbToYuv(RgbGreen()));
  EXPECT_RGB_NEAR(rgb_g, RgbGreen());

  Color rgb_b = bt2100YuvToRgb(bt2100RgbToYuv(RgbBlue()));
  EXPECT_RGB_NEAR(rgb_b, RgbBlue());
}

TEST_F(GainMapMathTest, YuvColorGamutConversion) {
  const std::array<Color, 5> SrgbYuvColors{YuvBlack(), YuvWhite(), SrgbYuvRed(), SrgbYuvGreen(),
                                           SrgbYuvBlue()};

  const std::array<Color, 5> P3YuvColors{YuvBlack(), YuvWhite(), P3YuvRed(), P3YuvGreen(),
                                         P3YuvBlue()};

  const std::array<Color, 5> Bt2100YuvColors{YuvBlack(), YuvWhite(), Bt2100YuvRed(),
                                             Bt2100YuvGreen(), Bt2100YuvBlue()};
  /*
   * Each tuple contains three elements.
   * 0. An array containing 9 coefficients needed to perform the color gamut conversion
   * 1. Array of colors to be used as test input
   * 2. Array of colors to used as reference output
   */
  const std::array<std::tuple<const std::array<float, 9>&, const std::array<Color, 5>,
                              const std::array<Color, 5>>,
                   6>
      coeffs_setup_expected{{
          {kYuvBt709ToBt601, SrgbYuvColors, P3YuvColors},
          {kYuvBt709ToBt2100, SrgbYuvColors, Bt2100YuvColors},
          {kYuvBt601ToBt709, P3YuvColors, SrgbYuvColors},
          {kYuvBt601ToBt2100, P3YuvColors, Bt2100YuvColors},
          {kYuvBt2100ToBt709, Bt2100YuvColors, SrgbYuvColors},
          {kYuvBt2100ToBt601, Bt2100YuvColors, P3YuvColors},
      }};

  for (const auto& [coeffs, input, expected] : coeffs_setup_expected) {
    for (size_t color_idx = 0; color_idx < SrgbYuvColors.size(); ++color_idx) {
      const Color input_color = input.at(color_idx);
      const Color output_color = yuvColorGamutConversion(input_color, coeffs);

      EXPECT_YUV_NEAR(expected.at(color_idx), output_color);
    }
  }
}

#if (defined(UHDR_ENABLE_INTRINSICS) && (defined(__ARM_NEON__) || defined(__ARM_NEON)))
TEST_F(GainMapMathTest, YuvConversionNeon) {
  const std::array<Pixel, 5> SrgbYuvColors{YuvBlackPixel(), YuvWhitePixel(), SrgbYuvRedPixel(),
                                           SrgbYuvGreenPixel(), SrgbYuvBluePixel()};

  const std::array<Pixel, 5> P3YuvColors{YuvBlackPixel(), YuvWhitePixel(), P3YuvRedPixel(),
                                         P3YuvGreenPixel(), P3YuvBluePixel()};

  const std::array<Pixel, 5> Bt2100YuvColors{YuvBlackPixel(), YuvWhitePixel(), Bt2100YuvRedPixel(),
                                             Bt2100YuvGreenPixel(), Bt2100YuvBluePixel()};

  struct InputSamples {
    std::array<uint8_t, 8> y;
    std::array<int16_t, 8> u;
    std::array<int16_t, 8> v;
  };

  struct ExpectedSamples {
    std::array<int16_t, 8> y;
    std::array<int16_t, 8> u;
    std::array<int16_t, 8> v;
  };

  // Each tuple contains three elements.
  // 0. A pointer to the coefficients that will be passed to the Neon implementation
  // 1. Input pixel/color array
  // 2. The expected results
  const std::array<
      std::tuple<const int16_t*, const std::array<Pixel, 5>, const std::array<Pixel, 5>>, 6>
      coeffs_setup_correct{{
          {kYuv709To601_coeffs_neon, SrgbYuvColors, P3YuvColors},
          {kYuv709To2100_coeffs_neon, SrgbYuvColors, Bt2100YuvColors},
          {kYuv601To709_coeffs_neon, P3YuvColors, SrgbYuvColors},
          {kYuv601To2100_coeffs_neon, P3YuvColors, Bt2100YuvColors},
          {kYuv2100To709_coeffs_neon, Bt2100YuvColors, SrgbYuvColors},
          {kYuv2100To601_coeffs_neon, Bt2100YuvColors, P3YuvColors},
      }};

  for (const auto& [coeff_ptr, input, expected] : coeffs_setup_correct) {
    const int16x8_t coeffs = vld1q_s16(coeff_ptr);
    InputSamples input_values;
    ExpectedSamples expected_values;
    for (size_t sample_idx = 0; sample_idx < 8; ++sample_idx) {
      size_t ring_idx = sample_idx % input.size();
      input_values.y.at(sample_idx) = static_cast<uint8_t>(input.at(ring_idx).y);
      input_values.u.at(sample_idx) = input.at(ring_idx).u;
      input_values.v.at(sample_idx) = input.at(ring_idx).v;

      expected_values.y.at(sample_idx) = expected.at(ring_idx).y;
      expected_values.u.at(sample_idx) = expected.at(ring_idx).u;
      expected_values.v.at(sample_idx) = expected.at(ring_idx).v;
    }

    const uint8x8_t y_neon = vld1_u8(input_values.y.data());
    const int16x8_t u_neon = vld1q_s16(input_values.u.data());
    const int16x8_t v_neon = vld1q_s16(input_values.v.data());

    const int16x8x3_t neon_result = yuvConversion_neon(y_neon, u_neon, v_neon, coeffs);

    const int16x8_t y_neon_result = neon_result.val[0];
    const int16x8_t u_neon_result = neon_result.val[1];
    const int16x8_t v_neon_result = neon_result.val[2];

    const Pixel result0 = {vgetq_lane_s16(y_neon_result, 0), vgetq_lane_s16(u_neon_result, 0),
                           vgetq_lane_s16(v_neon_result, 0)};

    const Pixel result1 = {vgetq_lane_s16(y_neon_result, 1), vgetq_lane_s16(u_neon_result, 1),
                           vgetq_lane_s16(v_neon_result, 1)};

    const Pixel result2 = {vgetq_lane_s16(y_neon_result, 2), vgetq_lane_s16(u_neon_result, 2),
                           vgetq_lane_s16(v_neon_result, 2)};

    const Pixel result3 = {vgetq_lane_s16(y_neon_result, 3), vgetq_lane_s16(u_neon_result, 3),
                           vgetq_lane_s16(v_neon_result, 3)};

    const Pixel result4 = {vgetq_lane_s16(y_neon_result, 4), vgetq_lane_s16(u_neon_result, 4),
                           vgetq_lane_s16(v_neon_result, 4)};

    const Pixel result5 = {vgetq_lane_s16(y_neon_result, 5), vgetq_lane_s16(u_neon_result, 5),
                           vgetq_lane_s16(v_neon_result, 5)};

    const Pixel result6 = {vgetq_lane_s16(y_neon_result, 6), vgetq_lane_s16(u_neon_result, 6),
                           vgetq_lane_s16(v_neon_result, 6)};

    const Pixel result7 = {vgetq_lane_s16(y_neon_result, 7), vgetq_lane_s16(u_neon_result, 7),
                           vgetq_lane_s16(v_neon_result, 7)};

    EXPECT_NEAR(result0.y, expected_values.y.at(0), 1);
    EXPECT_NEAR(result0.u, expected_values.u.at(0), 1);
    EXPECT_NEAR(result0.v, expected_values.v.at(0), 1);

    EXPECT_NEAR(result1.y, expected_values.y.at(1), 1);
    EXPECT_NEAR(result1.u, expected_values.u.at(1), 1);
    EXPECT_NEAR(result1.v, expected_values.v.at(1), 1);

    EXPECT_NEAR(result2.y, expected_values.y.at(2), 1);
    EXPECT_NEAR(result2.u, expected_values.u.at(2), 1);
    EXPECT_NEAR(result2.v, expected_values.v.at(2), 1);

    EXPECT_NEAR(result3.y, expected_values.y.at(3), 1);
    EXPECT_NEAR(result3.u, expected_values.u.at(3), 1);
    EXPECT_NEAR(result3.v, expected_values.v.at(3), 1);

    EXPECT_NEAR(result4.y, expected_values.y.at(4), 1);
    EXPECT_NEAR(result4.u, expected_values.u.at(4), 1);
    EXPECT_NEAR(result4.v, expected_values.v.at(4), 1);

    EXPECT_NEAR(result5.y, expected_values.y.at(5), 1);
    EXPECT_NEAR(result5.u, expected_values.u.at(5), 1);
    EXPECT_NEAR(result5.v, expected_values.v.at(5), 1);

    EXPECT_NEAR(result6.y, expected_values.y.at(6), 1);
    EXPECT_NEAR(result6.u, expected_values.u.at(6), 1);
    EXPECT_NEAR(result6.v, expected_values.v.at(6), 1);

    EXPECT_NEAR(result7.y, expected_values.y.at(7), 1);
    EXPECT_NEAR(result7.u, expected_values.u.at(7), 1);
    EXPECT_NEAR(result7.v, expected_values.v.at(7), 1);
  }
}
#endif

TEST_F(GainMapMathTest, TransformYuv420) {
  auto input = Yuv420Image();
  const size_t buf_size = input.w * input.h * 3 / 2;
  std::unique_ptr<uint8_t[]> out_buf = std::make_unique<uint8_t[]>(buf_size);
  uint8_t* luma = out_buf.get();
  uint8_t* cb = luma + input.w * input.h;
  uint8_t* cr = cb + input.w * input.h / 4;

  const std::array<std::array<float, 9>, 6> conversion_coeffs = {
      kYuvBt709ToBt601,  kYuvBt709ToBt2100, kYuvBt601ToBt709,
      kYuvBt601ToBt2100, kYuvBt2100ToBt709, kYuvBt2100ToBt601};

  for (size_t coeffs_idx = 0; coeffs_idx < conversion_coeffs.size(); ++coeffs_idx) {
    auto output = Yuv420Image();
    memcpy(luma, input.planes[UHDR_PLANE_Y], input.w * input.h);
    memcpy(cb, input.planes[UHDR_PLANE_U], input.w * input.h / 4);
    memcpy(cr, input.planes[UHDR_PLANE_V], input.w * input.h / 4);
    output.planes[UHDR_PLANE_Y] = luma;
    output.planes[UHDR_PLANE_U] = cb;
    output.planes[UHDR_PLANE_V] = cr;

    // Perform a color gamut conversion to the entire 4:2:0 image.
    transformYuv420(&output, conversion_coeffs.at(coeffs_idx));

    for (size_t y = 0; y < input.h; y += 2) {
      for (size_t x = 0; x < input.w; x += 2) {
        Pixel out1 = getYuv420Pixel_uint(&output, x, y);
        Pixel out2 = getYuv420Pixel_uint(&output, x + 1, y);
        Pixel out3 = getYuv420Pixel_uint(&output, x, y + 1);
        Pixel out4 = getYuv420Pixel_uint(&output, x + 1, y + 1);

        Color in1 = getYuv420Pixel(&input, x, y);
        Color in2 = getYuv420Pixel(&input, x + 1, y);
        Color in3 = getYuv420Pixel(&input, x, y + 1);
        Color in4 = getYuv420Pixel(&input, x + 1, y + 1);

        in1 = yuvColorGamutConversion(in1, conversion_coeffs.at(coeffs_idx));
        in2 = yuvColorGamutConversion(in2, conversion_coeffs.at(coeffs_idx));
        in3 = yuvColorGamutConversion(in3, conversion_coeffs.at(coeffs_idx));
        in4 = yuvColorGamutConversion(in4, conversion_coeffs.at(coeffs_idx));

        // Clamp and reduce to uint8_t from float.
        uint8_t expect_y1 = static_cast<uint8_t>(CLIP3((in1.y * 255.0f + 0.5f), 0, 255));
        uint8_t expect_y2 = static_cast<uint8_t>(CLIP3((in2.y * 255.0f + 0.5f), 0, 255));
        uint8_t expect_y3 = static_cast<uint8_t>(CLIP3((in3.y * 255.0f + 0.5f), 0, 255));
        uint8_t expect_y4 = static_cast<uint8_t>(CLIP3((in4.y * 255.0f + 0.5f), 0, 255));

        // Allow an absolute difference of 1 to allow for implmentations using a fixed-point
        // approximation.
        EXPECT_NEAR(expect_y1, out1.y, 1);
        EXPECT_NEAR(expect_y2, out2.y, 1);
        EXPECT_NEAR(expect_y3, out3.y, 1);
        EXPECT_NEAR(expect_y4, out4.y, 1);

        Color expect_uv = (in1 + in2 + in3 + in4) / 4.0f;

        uint8_t expect_u =
            static_cast<uint8_t>(CLIP3((expect_uv.u * 255.0f + 128.0f + 0.5f), 0, 255));
        uint8_t expect_v =
            static_cast<uint8_t>(CLIP3((expect_uv.v * 255.0f + 128.0f + 0.5f), 0, 255));

        EXPECT_NEAR(expect_u, out1.u, 1);
        EXPECT_NEAR(expect_u, out2.u, 1);
        EXPECT_NEAR(expect_u, out3.u, 1);
        EXPECT_NEAR(expect_u, out4.u, 1);

        EXPECT_NEAR(expect_v, out1.v, 1);
        EXPECT_NEAR(expect_v, out2.v, 1);
        EXPECT_NEAR(expect_v, out3.v, 1);
        EXPECT_NEAR(expect_v, out4.v, 1);
      }
    }
  }
}

#if (defined(UHDR_ENABLE_INTRINSICS) && (defined(__ARM_NEON__) || defined(__ARM_NEON)))
TEST_F(GainMapMathTest, TransformYuv420Neon) {
  const std::array<std::pair<const int16_t*, const std::array<float, 9>>, 6> fixed_floating_coeffs{
      {{kYuv709To601_coeffs_neon, kYuvBt709ToBt601},
       {kYuv709To2100_coeffs_neon, kYuvBt709ToBt2100},
       {kYuv601To709_coeffs_neon, kYuvBt601ToBt709},
       {kYuv601To2100_coeffs_neon, kYuvBt601ToBt2100},
       {kYuv2100To709_coeffs_neon, kYuvBt2100ToBt709},
       {kYuv2100To601_coeffs_neon, kYuvBt2100ToBt601}}};

  for (const auto& [neon_coeffs_ptr, floating_point_coeffs] : fixed_floating_coeffs) {
    uhdr_raw_image_t input = Yuv420Image32x4();
    const size_t buf_size = input.w * input.h * 3 / 2;
    std::unique_ptr<uint8_t[]> out_buf = std::make_unique<uint8_t[]>(buf_size);
    uint8_t* luma = out_buf.get();
    uint8_t* cb = luma + input.w * input.h;
    uint8_t* cr = cb + input.w * input.h / 4;

    uhdr_raw_image_t output = Yuv420Image32x4();
    memcpy(luma, input.planes[UHDR_PLANE_Y], input.w * input.h);
    memcpy(cb, input.planes[UHDR_PLANE_U], input.w * input.h / 4);
    memcpy(cr, input.planes[UHDR_PLANE_V], input.w * input.h / 4);
    output.planes[UHDR_PLANE_Y] = luma;
    output.planes[UHDR_PLANE_U] = cb;
    output.planes[UHDR_PLANE_V] = cr;

    transformYuv420_neon(&output, neon_coeffs_ptr);

    for (size_t y = 0; y < input.h / 2; ++y) {
      for (size_t x = 0; x < input.w / 2; ++x) {
        const Pixel out1 = getYuv420Pixel_uint(&output, x * 2, y * 2);
        const Pixel out2 = getYuv420Pixel_uint(&output, x * 2 + 1, y * 2);
        const Pixel out3 = getYuv420Pixel_uint(&output, x * 2, y * 2 + 1);
        const Pixel out4 = getYuv420Pixel_uint(&output, x * 2 + 1, y * 2 + 1);

        Color in1 = getYuv420Pixel(&input, x * 2, y * 2);
        Color in2 = getYuv420Pixel(&input, x * 2 + 1, y * 2);
        Color in3 = getYuv420Pixel(&input, x * 2, y * 2 + 1);
        Color in4 = getYuv420Pixel(&input, x * 2 + 1, y * 2 + 1);

        in1 = yuvColorGamutConversion(in1, floating_point_coeffs);
        in2 = yuvColorGamutConversion(in2, floating_point_coeffs);
        in3 = yuvColorGamutConversion(in3, floating_point_coeffs);
        in4 = yuvColorGamutConversion(in4, floating_point_coeffs);

        const Color expect_uv = (in1 + in2 + in3 + in4) / 4.0f;

        const uint8_t expect_y1 = static_cast<uint8_t>(CLIP3(in1.y * 255.0f + 0.5f, 0, 255));
        const uint8_t expect_y2 = static_cast<uint8_t>(CLIP3(in2.y * 255.0f + 0.5f, 0, 255));
        const uint8_t expect_y3 = static_cast<uint8_t>(CLIP3(in3.y * 255.0f + 0.5f, 0, 255));
        const uint8_t expect_y4 = static_cast<uint8_t>(CLIP3(in4.y * 255.0f + 0.5f, 0, 255));

        const uint8_t expect_u =
            static_cast<uint8_t>(CLIP3(expect_uv.u * 255.0f + 128.0f + 0.5f, 0, 255));
        const uint8_t expect_v =
            static_cast<uint8_t>(CLIP3(expect_uv.v * 255.0f + 128.0f + 0.5f, 0, 255));

        // Due to the Neon version using a fixed-point approximation, this can result in an off by
        // one error compared with the standard floating-point version.
        EXPECT_NEAR(expect_y1, out1.y, 1);
        EXPECT_NEAR(expect_y2, out2.y, 1);
        EXPECT_NEAR(expect_y3, out3.y, 1);
        EXPECT_NEAR(expect_y4, out4.y, 1);

        EXPECT_NEAR(expect_u, out1.u, 1);
        EXPECT_NEAR(expect_u, out2.u, 1);
        EXPECT_NEAR(expect_u, out3.u, 1);
        EXPECT_NEAR(expect_u, out4.u, 1);

        EXPECT_NEAR(expect_v, out1.v, 1);
        EXPECT_NEAR(expect_v, out2.v, 1);
        EXPECT_NEAR(expect_v, out3.v, 1);
        EXPECT_NEAR(expect_v, out4.v, 1);
      }
    }
  }
}
#endif

TEST_F(GainMapMathTest, HlgOetf) {
  EXPECT_FLOAT_EQ(hlgOetf(0.0f), 0.0f);
  EXPECT_NEAR(hlgOetf(0.04167f), 0.35357f, ComparisonEpsilon());
  EXPECT_NEAR(hlgOetf(0.08333f), 0.5f, ComparisonEpsilon());
  EXPECT_NEAR(hlgOetf(0.5f), 0.87164f, ComparisonEpsilon());
  EXPECT_FLOAT_EQ(hlgOetf(1.0f), 1.0f);

  Color e = {{{0.04167f, 0.08333f, 0.5f}}};
  Color e_gamma = {{{0.35357f, 0.5f, 0.87164f}}};
  EXPECT_RGB_NEAR(hlgOetf(e), e_gamma);
}

TEST_F(GainMapMathTest, HlgInvOetf) {
  EXPECT_FLOAT_EQ(hlgInvOetf(0.0f), 0.0f);
  EXPECT_NEAR(hlgInvOetf(0.25f), 0.02083f, ComparisonEpsilon());
  EXPECT_NEAR(hlgInvOetf(0.5f), 0.08333f, ComparisonEpsilon());
  EXPECT_NEAR(hlgInvOetf(0.75f), 0.26496f, ComparisonEpsilon());
  EXPECT_FLOAT_EQ(hlgInvOetf(1.0f), 1.0f);

  Color e_gamma = {{{0.25f, 0.5f, 0.75f}}};
  Color e = {{{0.02083f, 0.08333f, 0.26496f}}};
  EXPECT_RGB_NEAR(hlgInvOetf(e_gamma), e);
}

TEST_F(GainMapMathTest, HlgTransferFunctionRoundtrip) {
  EXPECT_FLOAT_EQ(hlgInvOetf(hlgOetf(0.0f)), 0.0f);
  EXPECT_NEAR(hlgInvOetf(hlgOetf(0.04167f)), 0.04167f, ComparisonEpsilon());
  EXPECT_NEAR(hlgInvOetf(hlgOetf(0.08333f)), 0.08333f, ComparisonEpsilon());
  EXPECT_NEAR(hlgInvOetf(hlgOetf(0.5f)), 0.5f, ComparisonEpsilon());
  EXPECT_FLOAT_EQ(hlgInvOetf(hlgOetf(1.0f)), 1.0f);
}

TEST_F(GainMapMathTest, PqOetf) {
  EXPECT_FLOAT_EQ(pqOetf(0.0f), 0.0f);
  EXPECT_NEAR(pqOetf(0.01f), 0.50808f, ComparisonEpsilon());
  EXPECT_NEAR(pqOetf(0.5f), 0.92655f, ComparisonEpsilon());
  EXPECT_NEAR(pqOetf(0.99f), 0.99895f, ComparisonEpsilon());
  EXPECT_FLOAT_EQ(pqOetf(1.0f), 1.0f);

  Color e = {{{0.01f, 0.5f, 0.99f}}};
  Color e_gamma = {{{0.50808f, 0.92655f, 0.99895f}}};
  EXPECT_RGB_NEAR(pqOetf(e), e_gamma);
}

TEST_F(GainMapMathTest, PqInvOetf) {
  EXPECT_FLOAT_EQ(pqInvOetf(0.0f), 0.0f);
  EXPECT_NEAR(pqInvOetf(0.01f), 2.31017e-7f, ComparisonEpsilon());
  EXPECT_NEAR(pqInvOetf(0.5f), 0.00922f, ComparisonEpsilon());
  EXPECT_NEAR(pqInvOetf(0.99f), 0.90903f, ComparisonEpsilon());
  EXPECT_FLOAT_EQ(pqInvOetf(1.0f), 1.0f);

  Color e_gamma = {{{0.01f, 0.5f, 0.99f}}};
  Color e = {{{2.31017e-7f, 0.00922f, 0.90903f}}};
  EXPECT_RGB_NEAR(pqInvOetf(e_gamma), e);
}

TEST_F(GainMapMathTest, PqInvOetfLUT) {
  for (size_t idx = 0; idx < kPqInvOETFNumEntries; idx++) {
    float value = static_cast<float>(idx) / static_cast<float>(kPqInvOETFNumEntries - 1);
    EXPECT_FLOAT_EQ(pqInvOetf(value), pqInvOetfLUT(value));
  }
}

TEST_F(GainMapMathTest, HlgInvOetfLUT) {
  for (size_t idx = 0; idx < kHlgInvOETFNumEntries; idx++) {
    float value = static_cast<float>(idx) / static_cast<float>(kHlgInvOETFNumEntries - 1);
    EXPECT_FLOAT_EQ(hlgInvOetf(value), hlgInvOetfLUT(value));
  }
}

TEST_F(GainMapMathTest, pqOetfLUT) {
  for (size_t idx = 0; idx < kPqOETFNumEntries; idx++) {
    float value = static_cast<float>(idx) / static_cast<float>(kPqOETFNumEntries - 1);
    EXPECT_FLOAT_EQ(pqOetf(value), pqOetfLUT(value));
  }
}

TEST_F(GainMapMathTest, hlgOetfLUT) {
  for (size_t idx = 0; idx < kHlgOETFNumEntries; idx++) {
    float value = static_cast<float>(idx) / static_cast<float>(kHlgOETFNumEntries - 1);
    EXPECT_FLOAT_EQ(hlgOetf(value), hlgOetfLUT(value));
  }
}

TEST_F(GainMapMathTest, srgbInvOetfLUT) {
  for (size_t idx = 0; idx < kSrgbInvOETFNumEntries; idx++) {
    float value = static_cast<float>(idx) / static_cast<float>(kSrgbInvOETFNumEntries - 1);
    EXPECT_FLOAT_EQ(srgbInvOetf(value), srgbInvOetfLUT(value));
  }
}

TEST_F(GainMapMathTest, applyGainLUT) {
  for (float boost = 1.5; boost <= 12; boost++) {
    uhdr_gainmap_metadata_ext_t metadata;

    metadata.min_content_boost = 1.0f / boost;
    metadata.max_content_boost = boost;
    metadata.gamma = 1.0f;
    metadata.hdr_capacity_max = metadata.max_content_boost;
    metadata.hdr_capacity_min = metadata.min_content_boost;
    GainLUT gainLUT(&metadata);
    float weight = (log2(boost) - log2(metadata.hdr_capacity_min)) /
                   (log2(metadata.hdr_capacity_max) - log2(metadata.hdr_capacity_min));
    weight = CLIP3(weight, 0.0f, 1.0f);
    GainLUT gainLUTWithBoost(&metadata, weight);
    for (size_t idx = 0; idx < kGainFactorNumEntries; idx++) {
      float value = static_cast<float>(idx) / static_cast<float>(kGainFactorNumEntries - 1);
      EXPECT_RGB_NEAR(applyGain(RgbBlack(), value, &metadata),
                      applyGainLUT(RgbBlack(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbWhite(), value, &metadata),
                      applyGainLUT(RgbWhite(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbRed(), value, &metadata),
                      applyGainLUT(RgbRed(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbGreen(), value, &metadata),
                      applyGainLUT(RgbGreen(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlue(), value, &metadata),
                      applyGainLUT(RgbBlue(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlack(), value, &metadata, weight),
                      applyGainLUT(RgbBlack(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbWhite(), value, &metadata, weight),
                      applyGainLUT(RgbWhite(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbRed(), value, &metadata, weight),
                      applyGainLUT(RgbRed(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbGreen(), value, &metadata, weight),
                      applyGainLUT(RgbGreen(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlue(), value, &metadata, weight),
                      applyGainLUT(RgbBlue(), value, gainLUTWithBoost, &metadata));
    }
  }

  for (float boost = 1.5; boost <= 12; boost++) {
    uhdr_gainmap_metadata_ext_t metadata;

    metadata.min_content_boost = 1.0f;
    metadata.max_content_boost = boost;
    metadata.gamma = 1.0f;
    metadata.hdr_capacity_max = metadata.max_content_boost;
    metadata.hdr_capacity_min = metadata.min_content_boost;
    GainLUT gainLUT(&metadata);
    float weight = (log2(boost) - log2(metadata.hdr_capacity_min)) /
                   (log2(metadata.hdr_capacity_max) - log2(metadata.hdr_capacity_min));
    weight = CLIP3(weight, 0.0f, 1.0f);
    GainLUT gainLUTWithBoost(&metadata, weight);
    for (size_t idx = 0; idx < kGainFactorNumEntries; idx++) {
      float value = static_cast<float>(idx) / static_cast<float>(kGainFactorNumEntries - 1);
      EXPECT_RGB_NEAR(applyGain(RgbBlack(), value, &metadata),
                      applyGainLUT(RgbBlack(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbWhite(), value, &metadata),
                      applyGainLUT(RgbWhite(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbRed(), value, &metadata),
                      applyGainLUT(RgbRed(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbGreen(), value, &metadata),
                      applyGainLUT(RgbGreen(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlue(), value, &metadata),
                      applyGainLUT(RgbBlue(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlack(), value, &metadata, weight),
                      applyGainLUT(RgbBlack(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbWhite(), value, &metadata, weight),
                      applyGainLUT(RgbWhite(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbRed(), value, &metadata, weight),
                      applyGainLUT(RgbRed(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbGreen(), value, &metadata, weight),
                      applyGainLUT(RgbGreen(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlue(), value, &metadata, weight),
                      applyGainLUT(RgbBlue(), value, gainLUTWithBoost, &metadata));
    }
  }

  for (float boost = 1.5; boost <= 12; boost++) {
    uhdr_gainmap_metadata_ext_t metadata;

    metadata.min_content_boost = 1.0f / powf(boost, 1.0f / 3.0f);
    metadata.max_content_boost = boost;
    metadata.gamma = 1.0f;
    metadata.hdr_capacity_max = metadata.max_content_boost;
    metadata.hdr_capacity_min = metadata.min_content_boost;
    GainLUT gainLUT(&metadata);
    float weight = (log2(boost) - log2(metadata.hdr_capacity_min)) /
                   (log2(metadata.hdr_capacity_max) - log2(metadata.hdr_capacity_min));
    weight = CLIP3(weight, 0.0f, 1.0f);
    GainLUT gainLUTWithBoost(&metadata, weight);
    for (size_t idx = 0; idx < kGainFactorNumEntries; idx++) {
      float value = static_cast<float>(idx) / static_cast<float>(kGainFactorNumEntries - 1);
      EXPECT_RGB_NEAR(applyGain(RgbBlack(), value, &metadata),
                      applyGainLUT(RgbBlack(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbWhite(), value, &metadata),
                      applyGainLUT(RgbWhite(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbRed(), value, &metadata),
                      applyGainLUT(RgbRed(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbGreen(), value, &metadata),
                      applyGainLUT(RgbGreen(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlue(), value, &metadata),
                      applyGainLUT(RgbBlue(), value, gainLUT, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlack(), value, &metadata, weight),
                      applyGainLUT(RgbBlack(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbWhite(), value, &metadata, weight),
                      applyGainLUT(RgbWhite(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbRed(), value, &metadata, weight),
                      applyGainLUT(RgbRed(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbGreen(), value, &metadata, weight),
                      applyGainLUT(RgbGreen(), value, gainLUTWithBoost, &metadata));
      EXPECT_RGB_NEAR(applyGain(RgbBlue(), value, &metadata, weight),
                      applyGainLUT(RgbBlue(), value, gainLUTWithBoost, &metadata));
    }
  }
}

TEST_F(GainMapMathTest, PqTransferFunctionRoundtrip) {
  EXPECT_FLOAT_EQ(pqInvOetf(pqOetf(0.0f)), 0.0f);
  EXPECT_NEAR(pqInvOetf(pqOetf(0.01f)), 0.01f, ComparisonEpsilon());
  EXPECT_NEAR(pqInvOetf(pqOetf(0.5f)), 0.5f, ComparisonEpsilon());
  EXPECT_NEAR(pqInvOetf(pqOetf(0.99f)), 0.99f, ComparisonEpsilon());
  EXPECT_FLOAT_EQ(pqInvOetf(pqOetf(1.0f)), 1.0f);
}

TEST_F(GainMapMathTest, ColorConversionLookup) {
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_709, UHDR_CG_UNSPECIFIED), nullptr);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_709, UHDR_CG_BT_709), identityConversion);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_709, UHDR_CG_DISPLAY_P3), p3ToBt709);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_709, UHDR_CG_BT_2100), bt2100ToBt709);

  EXPECT_EQ(getGamutConversionFn(UHDR_CG_DISPLAY_P3, UHDR_CG_UNSPECIFIED), nullptr);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_DISPLAY_P3, UHDR_CG_BT_709), bt709ToP3);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_DISPLAY_P3, UHDR_CG_DISPLAY_P3), identityConversion);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_DISPLAY_P3, UHDR_CG_BT_2100), bt2100ToP3);

  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_2100, UHDR_CG_UNSPECIFIED), nullptr);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_2100, UHDR_CG_BT_709), bt709ToBt2100);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_2100, UHDR_CG_DISPLAY_P3), p3ToBt2100);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_BT_2100, UHDR_CG_BT_2100), identityConversion);

  EXPECT_EQ(getGamutConversionFn(UHDR_CG_UNSPECIFIED, UHDR_CG_UNSPECIFIED), nullptr);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_UNSPECIFIED, UHDR_CG_BT_709), nullptr);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_UNSPECIFIED, UHDR_CG_DISPLAY_P3), nullptr);
  EXPECT_EQ(getGamutConversionFn(UHDR_CG_UNSPECIFIED, UHDR_CG_BT_2100), nullptr);
}

TEST_F(GainMapMathTest, EncodeGain) {
  float min_boost = log2(1.0f / 4.0f);
  float max_boost = log2(4.0f);
  float gamma = 1.0f;

  EXPECT_EQ(affineMapGain(computeGain(0.0f, 1.0f), min_boost, max_boost, 1.0f), 128);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 0.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(0.5f, 0.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 1.0), min_boost, max_boost, 1.0f), 128);

  EXPECT_EQ(affineMapGain(computeGain(1.0f, 4.0f), min_boost, max_boost, 1.0f), 255);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 5.0f), min_boost, max_boost, 1.0f), 255);
  EXPECT_EQ(affineMapGain(computeGain(4.0f, 1.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(4.0f, 0.5f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 2.0f), min_boost, max_boost, 1.0f), 191);
  EXPECT_EQ(affineMapGain(computeGain(2.0f, 1.0f), min_boost, max_boost, 1.0f), 64);

  min_boost = log2(1.0f / 2.0f);
  max_boost = log2(2.0f);

  EXPECT_EQ(affineMapGain(computeGain(1.0f, 2.0f), min_boost, max_boost, 1.0f), 255);
  EXPECT_EQ(affineMapGain(computeGain(2.0f, 1.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 1.41421f), min_boost, max_boost, 1.0f), 191);
  EXPECT_EQ(affineMapGain(computeGain(1.41421f, 1.0f), min_boost, max_boost, 1.0f), 64);

  min_boost = log2(1.0f / 8.0f);
  max_boost = log2(8.0f);

  EXPECT_EQ(affineMapGain(computeGain(1.0f, 8.0f), min_boost, max_boost, 1.0f), 255);
  EXPECT_EQ(affineMapGain(computeGain(8.0f, 1.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 2.82843f), min_boost, max_boost, 1.0f), 191);
  EXPECT_EQ(affineMapGain(computeGain(2.82843f, 1.0f), min_boost, max_boost, 1.0f), 64);

  min_boost = log2(1.0f);
  max_boost = log2(8.0f);

  EXPECT_EQ(affineMapGain(computeGain(0.0f, 0.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 0.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 1.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 8.0f), min_boost, max_boost, 1.0f), 255);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 4.0f), min_boost, max_boost, 1.0f), 170);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 2.0f), min_boost, max_boost, 1.0f), 85);

  min_boost = log2(1.0f / 2.0f);
  max_boost = log2(8.0f);

  EXPECT_EQ(affineMapGain(computeGain(0.0f, 0.0f), min_boost, max_boost, 1.0f), 64);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 0.0f), min_boost, max_boost, 1.0f), 0);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 1.0f), min_boost, max_boost, 1.0f), 64);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 8.0f), min_boost, max_boost, 1.0f), 255);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 4.0f), min_boost, max_boost, 1.0f), 191);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 2.0f), min_boost, max_boost, 1.0f), 128);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 0.7071f), min_boost, max_boost, 1.0f), 32);
  EXPECT_EQ(affineMapGain(computeGain(1.0f, 0.5f), min_boost, max_boost, 1.0f), 0);
}

TEST_F(GainMapMathTest, ApplyGain) {
  uhdr_gainmap_metadata_ext_t metadata;

  metadata.min_content_boost = 1.0f / 4.0f;
  metadata.max_content_boost = 4.0f;
  metadata.hdr_capacity_max = metadata.max_content_boost;
  metadata.hdr_capacity_min = metadata.min_content_boost;
  metadata.offset_sdr = 0.0f;
  metadata.offset_hdr = 0.0f;
  metadata.gamma = 1.0f;

  EXPECT_RGB_NEAR(applyGain(RgbBlack(), 0.0f, &metadata), RgbBlack());
  EXPECT_RGB_NEAR(applyGain(RgbBlack(), 0.5f, &metadata), RgbBlack());
  EXPECT_RGB_NEAR(applyGain(RgbBlack(), 1.0f, &metadata), RgbBlack());

  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.0f, &metadata), RgbWhite() / 4.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.25f, &metadata), RgbWhite() / 2.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.5f, &metadata), RgbWhite());
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.75f, &metadata), RgbWhite() * 2.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 1.0f, &metadata), RgbWhite() * 4.0f);

  metadata.max_content_boost = 2.0f;
  metadata.min_content_boost = 1.0f / 2.0f;
  metadata.hdr_capacity_max = metadata.max_content_boost;
  metadata.hdr_capacity_min = metadata.min_content_boost;

  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.0f, &metadata), RgbWhite() / 2.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.25f, &metadata), RgbWhite() / 1.41421f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.5f, &metadata), RgbWhite());
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.75f, &metadata), RgbWhite() * 1.41421f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 1.0f, &metadata), RgbWhite() * 2.0f);

  metadata.max_content_boost = 8.0f;
  metadata.min_content_boost = 1.0f / 8.0f;
  metadata.hdr_capacity_max = metadata.max_content_boost;
  metadata.hdr_capacity_min = metadata.min_content_boost;

  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.0f, &metadata), RgbWhite() / 8.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.25f, &metadata), RgbWhite() / 2.82843f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.5f, &metadata), RgbWhite());
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.75f, &metadata), RgbWhite() * 2.82843f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 1.0f, &metadata), RgbWhite() * 8.0f);

  metadata.max_content_boost = 8.0f;
  metadata.min_content_boost = 1.0f;
  metadata.hdr_capacity_max = metadata.max_content_boost;
  metadata.hdr_capacity_min = metadata.min_content_boost;

  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.0f, &metadata), RgbWhite());
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 1.0f / 3.0f, &metadata), RgbWhite() * 2.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 2.0f / 3.0f, &metadata), RgbWhite() * 4.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 1.0f, &metadata), RgbWhite() * 8.0f);

  metadata.max_content_boost = 8.0f;
  metadata.min_content_boost = 0.5f;
  metadata.hdr_capacity_max = metadata.max_content_boost;
  metadata.hdr_capacity_min = metadata.min_content_boost;

  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.0f, &metadata), RgbWhite() / 2.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.25f, &metadata), RgbWhite());
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.5f, &metadata), RgbWhite() * 2.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 0.75f, &metadata), RgbWhite() * 4.0f);
  EXPECT_RGB_NEAR(applyGain(RgbWhite(), 1.0f, &metadata), RgbWhite() * 8.0f);

  Color e = {{{0.0f, 0.5f, 1.0f}}};
  metadata.max_content_boost = 4.0f;
  metadata.min_content_boost = 1.0f / 4.0f;
  metadata.hdr_capacity_max = metadata.max_content_boost;
  metadata.hdr_capacity_min = metadata.min_content_boost;

  EXPECT_RGB_NEAR(applyGain(e, 0.0f, &metadata), e / 4.0f);
  EXPECT_RGB_NEAR(applyGain(e, 0.25f, &metadata), e / 2.0f);
  EXPECT_RGB_NEAR(applyGain(e, 0.5f, &metadata), e);
  EXPECT_RGB_NEAR(applyGain(e, 0.75f, &metadata), e * 2.0f);
  EXPECT_RGB_NEAR(applyGain(e, 1.0f, &metadata), e * 4.0f);
}

TEST_F(GainMapMathTest, GetYuv420Pixel) {
  auto image = Yuv420Image();
  Color(*colors)[4] = Yuv420Colors();

  for (size_t y = 0; y < 4; ++y) {
    for (size_t x = 0; x < 4; ++x) {
      EXPECT_YUV_NEAR(getYuv420Pixel(&image, x, y), colors[y][x]);
    }
  }
}

TEST_F(GainMapMathTest, GetP010Pixel) {
  auto image = P010Image();
  Color(*colors)[4] = P010Colors();

  for (size_t y = 0; y < 4; ++y) {
    for (size_t x = 0; x < 4; ++x) {
      EXPECT_YUV_NEAR(getP010Pixel(&image, x, y), colors[y][x]);
    }
  }
}

TEST_F(GainMapMathTest, SampleYuv420) {
  auto image = Yuv420Image();
  Color(*colors)[4] = Yuv420Colors();

  static const size_t kMapScaleFactor = 2;
  for (size_t y = 0; y < 4 / kMapScaleFactor; ++y) {
    for (size_t x = 0; x < 4 / kMapScaleFactor; ++x) {
      Color min = {{{1.0f, 1.0f, 1.0f}}};
      Color max = {{{-1.0f, -1.0f, -1.0f}}};

      for (size_t dy = 0; dy < kMapScaleFactor; ++dy) {
        for (size_t dx = 0; dx < kMapScaleFactor; ++dx) {
          Color e = colors[y * kMapScaleFactor + dy][x * kMapScaleFactor + dx];
          min = ColorMin(min, e);
          max = ColorMax(max, e);
        }
      }

      // Instead of reimplementing the sampling algorithm, confirm that the
      // sample output is within the range of the min and max of the nearest
      // points.
      EXPECT_YUV_BETWEEN(sampleYuv420(&image, kMapScaleFactor, x, y), min, max);
    }
  }
}

TEST_F(GainMapMathTest, SampleP010) {
  auto image = P010Image();
  Color(*colors)[4] = P010Colors();

  static const size_t kMapScaleFactor = 2;
  for (size_t y = 0; y < 4 / kMapScaleFactor; ++y) {
    for (size_t x = 0; x < 4 / kMapScaleFactor; ++x) {
      Color min = {{{1.0f, 1.0f, 1.0f}}};
      Color max = {{{-1.0f, -1.0f, -1.0f}}};

      for (size_t dy = 0; dy < kMapScaleFactor; ++dy) {
        for (size_t dx = 0; dx < kMapScaleFactor; ++dx) {
          Color e = colors[y * kMapScaleFactor + dy][x * kMapScaleFactor + dx];
          min = ColorMin(min, e);
          max = ColorMax(max, e);
        }
      }

      // Instead of reimplementing the sampling algorithm, confirm that the
      // sample output is within the range of the min and max of the nearest
      // points.
      EXPECT_YUV_BETWEEN(sampleP010(&image, kMapScaleFactor, x, y), min, max);
    }
  }
}

TEST_F(GainMapMathTest, SampleMap) {
  auto image = MapImage();
  float(*values)[4] = MapValues();

  static const size_t kMapScaleFactor = 2;
  ShepardsIDW idwTable(kMapScaleFactor);
  for (size_t y = 0; y < 4 * kMapScaleFactor; ++y) {
    for (size_t x = 0; x < 4 * kMapScaleFactor; ++x) {
      size_t x_base = x / kMapScaleFactor;
      size_t y_base = y / kMapScaleFactor;

      float min = 1.0f;
      float max = -1.0f;

      min = fmin(min, values[y_base][x_base]);
      max = fmax(max, values[y_base][x_base]);
      if (y_base + 1 < 4) {
        min = fmin(min, values[y_base + 1][x_base]);
        max = fmax(max, values[y_base + 1][x_base]);
      }
      if (x_base + 1 < 4) {
        min = fmin(min, values[y_base][x_base + 1]);
        max = fmax(max, values[y_base][x_base + 1]);
      }
      if (y_base + 1 < 4 && x_base + 1 < 4) {
        min = fmin(min, values[y_base + 1][x_base + 1]);
        max = fmax(max, values[y_base + 1][x_base + 1]);
      }

      // Instead of reimplementing the sampling algorithm, confirm that the
      // sample output is within the range of the min and max of the nearest
      // points.
      EXPECT_THAT(sampleMap(&image, kMapScaleFactor, x, y),
                  testing::AllOf(testing::Ge(min), testing::Le(max)));
      EXPECT_EQ(sampleMap(&image, kMapScaleFactor, x, y, idwTable),
                sampleMap(&image, kMapScaleFactor, x, y));
    }
  }
}

TEST_F(GainMapMathTest, ColorToRgba1010102) {
  EXPECT_EQ(colorToRgba1010102(RgbBlack()), 0x3 << 30);
  EXPECT_EQ(colorToRgba1010102(RgbWhite()), 0xFFFFFFFF);
  EXPECT_EQ(colorToRgba1010102(RgbRed()), 0x3 << 30 | 0x3ff);
  EXPECT_EQ(colorToRgba1010102(RgbGreen()), 0x3 << 30 | 0x3ff << 10);
  EXPECT_EQ(colorToRgba1010102(RgbBlue()), 0x3 << 30 | 0x3ff << 20);

  Color e_gamma = {{{0.1f, 0.2f, 0.3f}}};
  EXPECT_EQ(colorToRgba1010102(e_gamma),
            0x3 << 30 | static_cast<uint32_t>(0.1f * static_cast<float>(0x3ff) + 0.5) |
                static_cast<uint32_t>(0.2f * static_cast<float>(0x3ff) + 0.5) << 10 |
                static_cast<uint32_t>(0.3f * static_cast<float>(0x3ff) + 0.5) << 20);
}

TEST_F(GainMapMathTest, ColorToRgbaF16) {
  EXPECT_EQ(colorToRgbaF16(RgbBlack()), ((uint64_t)0x3C00) << 48);
  EXPECT_EQ(colorToRgbaF16(RgbWhite()), 0x3C003C003C003C00);
  EXPECT_EQ(colorToRgbaF16(RgbRed()), (((uint64_t)0x3C00) << 48) | ((uint64_t)0x3C00));
  EXPECT_EQ(colorToRgbaF16(RgbGreen()), (((uint64_t)0x3C00) << 48) | (((uint64_t)0x3C00) << 16));
  EXPECT_EQ(colorToRgbaF16(RgbBlue()), (((uint64_t)0x3C00) << 48) | (((uint64_t)0x3C00) << 32));

  Color e_gamma = {{{0.1f, 0.2f, 0.3f}}};
  EXPECT_EQ(colorToRgbaF16(e_gamma), 0x3C0034CD32662E66);
}

TEST_F(GainMapMathTest, Float32ToFloat16) {
  EXPECT_EQ(floatToHalf(0.1f), 0x2E66);
  EXPECT_EQ(floatToHalf(0.0f), 0x0);
  EXPECT_EQ(floatToHalf(1.0f), 0x3C00);
  EXPECT_EQ(floatToHalf(-1.0f), 0xBC00);
  EXPECT_EQ(floatToHalf(0x1.fffffep127f), 0x7FFF);   // float max
  EXPECT_EQ(floatToHalf(-0x1.fffffep127f), 0xFFFF);  // float min
  EXPECT_EQ(floatToHalf(0x1.0p-126f), 0x0);          // float zero
}

TEST_F(GainMapMathTest, GenerateMapLuminanceSrgb) {
  EXPECT_FLOAT_EQ(SrgbYuvToLuminance(YuvBlack(), srgbLuminance), 0.0f);
  EXPECT_FLOAT_EQ(SrgbYuvToLuminance(YuvWhite(), srgbLuminance), kSdrWhiteNits);
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvRed(), srgbLuminance),
              srgbLuminance(RgbRed()) * kSdrWhiteNits, LuminanceEpsilon());
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvGreen(), srgbLuminance),
              srgbLuminance(RgbGreen()) * kSdrWhiteNits, LuminanceEpsilon());
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvBlue(), srgbLuminance),
              srgbLuminance(RgbBlue()) * kSdrWhiteNits, LuminanceEpsilon());
}

TEST_F(GainMapMathTest, GenerateMapLuminanceSrgbP3) {
  EXPECT_FLOAT_EQ(SrgbYuvToLuminance(YuvBlack(), p3Luminance), 0.0f);
  EXPECT_FLOAT_EQ(SrgbYuvToLuminance(YuvWhite(), p3Luminance), kSdrWhiteNits);
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvRed(), p3Luminance), p3Luminance(RgbRed()) * kSdrWhiteNits,
              LuminanceEpsilon());
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvGreen(), p3Luminance),
              p3Luminance(RgbGreen()) * kSdrWhiteNits, LuminanceEpsilon());
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvBlue(), p3Luminance),
              p3Luminance(RgbBlue()) * kSdrWhiteNits, LuminanceEpsilon());
}

TEST_F(GainMapMathTest, GenerateMapLuminanceSrgbBt2100) {
  EXPECT_FLOAT_EQ(SrgbYuvToLuminance(YuvBlack(), bt2100Luminance), 0.0f);
  EXPECT_FLOAT_EQ(SrgbYuvToLuminance(YuvWhite(), bt2100Luminance), kSdrWhiteNits);
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvRed(), bt2100Luminance),
              bt2100Luminance(RgbRed()) * kSdrWhiteNits, LuminanceEpsilon());
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvGreen(), bt2100Luminance),
              bt2100Luminance(RgbGreen()) * kSdrWhiteNits, LuminanceEpsilon());
  EXPECT_NEAR(SrgbYuvToLuminance(SrgbYuvBlue(), bt2100Luminance),
              bt2100Luminance(RgbBlue()) * kSdrWhiteNits, LuminanceEpsilon());
}

TEST_F(GainMapMathTest, GenerateMapLuminanceHlg) {
  EXPECT_FLOAT_EQ(Bt2100YuvToLuminance(YuvBlack(), hlgInvOetf, identityConversion, bt2100Luminance,
                                       kHlgMaxNits),
                  0.0f);
  EXPECT_FLOAT_EQ(Bt2100YuvToLuminance(YuvWhite(), hlgInvOetf, identityConversion, bt2100Luminance,
                                       kHlgMaxNits),
                  kHlgMaxNits);
  EXPECT_NEAR(Bt2100YuvToLuminance(Bt2100YuvRed(), hlgInvOetf, identityConversion, bt2100Luminance,
                                   kHlgMaxNits),
              bt2100Luminance(RgbRed()) * kHlgMaxNits, LuminanceEpsilon());
  EXPECT_NEAR(Bt2100YuvToLuminance(Bt2100YuvGreen(), hlgInvOetf, identityConversion,
                                   bt2100Luminance, kHlgMaxNits),
              bt2100Luminance(RgbGreen()) * kHlgMaxNits, LuminanceEpsilon());
  EXPECT_NEAR(Bt2100YuvToLuminance(Bt2100YuvBlue(), hlgInvOetf, identityConversion, bt2100Luminance,
                                   kHlgMaxNits),
              bt2100Luminance(RgbBlue()) * kHlgMaxNits, LuminanceEpsilon());
}

TEST_F(GainMapMathTest, GenerateMapLuminancePq) {
  EXPECT_FLOAT_EQ(
      Bt2100YuvToLuminance(YuvBlack(), pqInvOetf, identityConversion, bt2100Luminance, kPqMaxNits),
      0.0f);
  EXPECT_FLOAT_EQ(
      Bt2100YuvToLuminance(YuvWhite(), pqInvOetf, identityConversion, bt2100Luminance, kPqMaxNits),
      kPqMaxNits);
  EXPECT_NEAR(Bt2100YuvToLuminance(Bt2100YuvRed(), pqInvOetf, identityConversion, bt2100Luminance,
                                   kPqMaxNits),
              bt2100Luminance(RgbRed()) * kPqMaxNits, LuminanceEpsilon());
  EXPECT_NEAR(Bt2100YuvToLuminance(Bt2100YuvGreen(), pqInvOetf, identityConversion, bt2100Luminance,
                                   kPqMaxNits),
              bt2100Luminance(RgbGreen()) * kPqMaxNits, LuminanceEpsilon());
  EXPECT_NEAR(Bt2100YuvToLuminance(Bt2100YuvBlue(), pqInvOetf, identityConversion, bt2100Luminance,
                                   kPqMaxNits),
              bt2100Luminance(RgbBlue()) * kPqMaxNits, LuminanceEpsilon());
}

TEST_F(GainMapMathTest, ApplyMap) {
  uhdr_gainmap_metadata_ext_t metadata;

  metadata.min_content_boost = 1.0f / 8.0f;
  metadata.max_content_boost = 8.0f;
  metadata.offset_sdr = 0.0f;
  metadata.offset_hdr = 0.0f;
  metadata.gamma = 1.0f;

  EXPECT_RGB_EQ(Recover(YuvWhite(), 1.0f, &metadata), RgbWhite() * 8.0f);
  EXPECT_RGB_EQ(Recover(YuvBlack(), 1.0f, &metadata), RgbBlack());
  EXPECT_RGB_CLOSE(Recover(SrgbYuvRed(), 1.0f, &metadata), RgbRed() * 8.0f);
  EXPECT_RGB_CLOSE(Recover(SrgbYuvGreen(), 1.0f, &metadata), RgbGreen() * 8.0f);
  EXPECT_RGB_CLOSE(Recover(SrgbYuvBlue(), 1.0f, &metadata), RgbBlue() * 8.0f);

  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.75f, &metadata), RgbWhite() * sqrt(8.0f));
  EXPECT_RGB_EQ(Recover(YuvBlack(), 0.75f, &metadata), RgbBlack());
  EXPECT_RGB_CLOSE(Recover(SrgbYuvRed(), 0.75f, &metadata), RgbRed() * sqrt(8.0f));
  EXPECT_RGB_CLOSE(Recover(SrgbYuvGreen(), 0.75f, &metadata), RgbGreen() * sqrt(8.0f));
  EXPECT_RGB_CLOSE(Recover(SrgbYuvBlue(), 0.75f, &metadata), RgbBlue() * sqrt(8.0f));

  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.5f, &metadata), RgbWhite());
  EXPECT_RGB_EQ(Recover(YuvBlack(), 0.5f, &metadata), RgbBlack());
  EXPECT_RGB_CLOSE(Recover(SrgbYuvRed(), 0.5f, &metadata), RgbRed());
  EXPECT_RGB_CLOSE(Recover(SrgbYuvGreen(), 0.5f, &metadata), RgbGreen());
  EXPECT_RGB_CLOSE(Recover(SrgbYuvBlue(), 0.5f, &metadata), RgbBlue());

  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.25f, &metadata), RgbWhite() / sqrt(8.0f));
  EXPECT_RGB_EQ(Recover(YuvBlack(), 0.25f, &metadata), RgbBlack());
  EXPECT_RGB_CLOSE(Recover(SrgbYuvRed(), 0.25f, &metadata), RgbRed() / sqrt(8.0f));
  EXPECT_RGB_CLOSE(Recover(SrgbYuvGreen(), 0.25f, &metadata), RgbGreen() / sqrt(8.0f));
  EXPECT_RGB_CLOSE(Recover(SrgbYuvBlue(), 0.25f, &metadata), RgbBlue() / sqrt(8.0f));

  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.0f, &metadata), RgbWhite() / 8.0f);
  EXPECT_RGB_EQ(Recover(YuvBlack(), 0.0f, &metadata), RgbBlack());
  EXPECT_RGB_CLOSE(Recover(SrgbYuvRed(), 0.0f, &metadata), RgbRed() / 8.0f);
  EXPECT_RGB_CLOSE(Recover(SrgbYuvGreen(), 0.0f, &metadata), RgbGreen() / 8.0f);
  EXPECT_RGB_CLOSE(Recover(SrgbYuvBlue(), 0.0f, &metadata), RgbBlue() / 8.0f);

  metadata.max_content_boost = 8.0f;
  metadata.min_content_boost = 1.0f;

  EXPECT_RGB_EQ(Recover(YuvWhite(), 1.0f, &metadata), RgbWhite() * 8.0f);
  EXPECT_RGB_EQ(Recover(YuvWhite(), 2.0f / 3.0f, &metadata), RgbWhite() * 4.0f);
  EXPECT_RGB_EQ(Recover(YuvWhite(), 1.0f / 3.0f, &metadata), RgbWhite() * 2.0f);
  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.0f, &metadata), RgbWhite());

  metadata.max_content_boost = 8.0f;
  metadata.min_content_boost = 0.5f;

  EXPECT_RGB_EQ(Recover(YuvWhite(), 1.0f, &metadata), RgbWhite() * 8.0f);
  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.75, &metadata), RgbWhite() * 4.0f);
  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.5f, &metadata), RgbWhite() * 2.0f);
  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.25f, &metadata), RgbWhite());
  EXPECT_RGB_EQ(Recover(YuvWhite(), 0.0f, &metadata), RgbWhite() / 2.0f);
}

}  // namespace ultrahdr