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Fix ARM NEON wide-gamut color conversion #447

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Fix ARM NEON wide-gamut color conversion #447

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14 changes: 7 additions & 7 deletions lib/src/dsp/arm/gainmapmath_neon.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -324,12 +324,12 @@ uhdr_error_info_t convertYuv_neon(uhdr_raw_image_t* image, uhdr_color_gamut_t sr
ALIGNED(16)
const uint16_t kRgb709ToYuv_coeffs_neon[8] = {3484, 11717, 1183, 1877, 6315, 8192, 7441, 751};

// RGB Display P3 -> Yuv Display P3
// Y = 0.2289746 * R + 0.6917385 * G + 0.0792869 * B
// U = -0.124346335 * R + -0.375653665 * G + 0.5 * B
// V = 0.5 * R + -0.448583471 * G + -0.051416529 * B
// RGB Display P3 -> YUV using BT.601 luma coefficients, matching p3RgbToYuv().
// Y = 0.299 * R + 0.587 * G + 0.114 * B
// U = -0.168735892 * R + -0.331264108 * G + 0.5 * B
// V = 0.5 * R + -0.418687589 * G + -0.081312411 * B
ALIGNED(16)
const uint16_t kRgbDispP3ToYuv_coeffs_neon[8] = {3752, 11333, 1299, 2037, 6155, 8192, 7350, 842};
const uint16_t kRgb601ToYuv_coeffs_neon[8] = {4899, 9617, 1868, 2765, 5427, 8192, 6860, 1332};

// RGB Bt2100 -> Yuv Bt2100
// Y = 0.2627 * R + 0.677998 * G + 0.059302 * B
Expand Down Expand Up @@ -456,9 +456,9 @@ std::unique_ptr<uhdr_raw_image_ext_t> convert_raw_input_to_ycbcr_neon(uhdr_raw_i
if (src->cg == UHDR_CG_BT_709) {
coeffs_ptr = kRgb709ToYuv_coeffs_neon;
} else if (src->cg == UHDR_CG_BT_2100) {
coeffs_ptr = kRgbDispP3ToYuv_coeffs_neon;
} else if (src->cg == UHDR_CG_DISPLAY_P3) {
coeffs_ptr = kRgb2100ToYuv_coeffs_neon;
} else if (src->cg == UHDR_CG_DISPLAY_P3) {
coeffs_ptr = kRgb601ToYuv_coeffs_neon;
} else {
return dst;
}
Expand Down
45 changes: 45 additions & 0 deletions tests/gainmapmath_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,8 @@
#include <gtest/gtest.h>
#include <gmock/gmock.h>

#include <vector>

#include "ultrahdr/gainmapmath.h"
#ifdef UHDR_ENABLE_SMPTE2094_50
#include "smpte2094_50/smpte2094_50.h"
Expand Down Expand Up @@ -875,6 +877,49 @@ TEST_F(GainMapMathTest, YuvConversionNeon) {
EXPECT_NEAR(result7.v, expected_values.v.at(7), 1);
}
}

TEST_F(GainMapMathTest, Rgba8888ToYuv444NeonMatchesScalarForWideGamuts) {
constexpr size_t kWidth = 16;
constexpr size_t kHeight = 1;
const std::array<std::array<uint8_t, 4>, 4> colors{{
{{255, 0, 0, 255}},
{{0, 255, 0, 255}},
{{0, 0, 255, 255}},
{{37, 149, 233, 255}},
}};

std::vector<uint8_t> rgba(kWidth * kHeight * 4);
for (size_t x = 0; x < kWidth; ++x) {
std::copy(colors[x % colors.size()].begin(), colors[x % colors.size()].end(),
rgba.begin() + x * 4);
}

for (uhdr_color_gamut_t gamut : {UHDR_CG_DISPLAY_P3, UHDR_CG_BT_2100}) {
uhdr_raw_image_t source{};
source.fmt = UHDR_IMG_FMT_32bppRGBA8888;
source.cg = gamut;
source.ct = UHDR_CT_SRGB;
source.range = UHDR_CR_FULL_RANGE;
source.w = kWidth;
source.h = kHeight;
source.planes[UHDR_PLANE_PACKED] = rgba.data();
source.stride[UHDR_PLANE_PACKED] = kWidth;

auto scalar = convert_raw_input_to_ycbcr(&source);
auto neon = convert_raw_input_to_ycbcr_neon(&source);
ASSERT_NE(scalar, nullptr);
ASSERT_NE(neon, nullptr);

for (auto plane : {UHDR_PLANE_Y, UHDR_PLANE_U, UHDR_PLANE_V}) {
const auto* scalar_data = static_cast<const uint8_t*>(scalar->planes[plane]);
const auto* neon_data = static_cast<const uint8_t*>(neon->planes[plane]);
for (size_t x = 0; x < kWidth; ++x) {
EXPECT_NEAR(scalar_data[x], neon_data[x], 1)
<< "gamut=" << gamut << ", plane=" << plane << ", x=" << x;
}
}
}
}
#endif

TEST_F(GainMapMathTest, TransformYuv420) {
Expand Down
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