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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "lib/jxl/alpha.h"
#include "lib/jxl/test_utils.h"
#include "lib/jxl/testing.h"
namespace jxl {
namespace {
using ::testing::_;
using ::testing::ElementsAre;
using ::testing::FloatNear;
TEST(AlphaTest, BlendingWithNonPremultiplied) {
const float bg_rgb[3] = {100, 110, 120};
const float bg_a = 180.f / 255;
const float fg_rgb[3] = {25, 21, 23};
const float fg_a = 15420.f / 65535;
const float fg_a2 = 2.0f;
float out_rgb[3];
float out_a;
PerformAlphaBlending(
/*bg=*/{&bg_rgb[0], &bg_rgb[1], &bg_rgb[2], &bg_a},
/*fg=*/{&fg_rgb[0], &fg_rgb[1], &fg_rgb[2], &fg_a},
/*out=*/{&out_rgb[0], &out_rgb[1], &out_rgb[2], &out_a}, 1,
/*alpha_is_premultiplied=*/false, /*clamp=*/false);
EXPECT_THAT(out_rgb,
ElementsAre(FloatNear(77.2f, .05f), FloatNear(83.0f, .05f),
FloatNear(90.6f, .05f)));
EXPECT_NEAR(out_a, 3174.f / 4095, 1e-5);
PerformAlphaBlending(
/*bg=*/{&bg_rgb[0], &bg_rgb[1], &bg_rgb[2], &bg_a},
/*fg=*/{&fg_rgb[0], &fg_rgb[1], &fg_rgb[2], &fg_a2},
/*out=*/{&out_rgb[0], &out_rgb[1], &out_rgb[2], &out_a}, 1,
/*alpha_is_premultiplied=*/false, /*clamp=*/true);
EXPECT_THAT(out_rgb, ElementsAre(FloatNear(fg_rgb[0], .05f),
FloatNear(fg_rgb[1], .05f),
FloatNear(fg_rgb[2], .05f)));
EXPECT_NEAR(out_a, 1.0f, 1e-5);
}
TEST(AlphaTest, BlendingWithPremultiplied) {
const float bg_rgb[3] = {100, 110, 120};
const float bg_a = 180.f / 255;
const float fg_rgb[3] = {25, 21, 23};
const float fg_a = 15420.f / 65535;
const float fg_a2 = 2.0f;
float out_rgb[3];
float out_a;
PerformAlphaBlending(
/*bg=*/{&bg_rgb[0], &bg_rgb[1], &bg_rgb[2], &bg_a},
/*fg=*/{&fg_rgb[0], &fg_rgb[1], &fg_rgb[2], &fg_a},
/*out=*/{&out_rgb[0], &out_rgb[1], &out_rgb[2], &out_a}, 1,
/*alpha_is_premultiplied=*/true, /*clamp=*/false);
EXPECT_THAT(out_rgb,
ElementsAre(FloatNear(101.5f, .05f), FloatNear(105.1f, .05f),
FloatNear(114.8f, .05f)));
EXPECT_NEAR(out_a, 3174.f / 4095, 1e-5);
PerformAlphaBlending(
/*bg=*/{&bg_rgb[0], &bg_rgb[1], &bg_rgb[2], &bg_a},
/*fg=*/{&fg_rgb[0], &fg_rgb[1], &fg_rgb[2], &fg_a2},
/*out=*/{&out_rgb[0], &out_rgb[1], &out_rgb[2], &out_a}, 1,
/*alpha_is_premultiplied=*/true, /*clamp=*/true);
EXPECT_THAT(out_rgb, ElementsAre(FloatNear(fg_rgb[0], .05f),
FloatNear(fg_rgb[1], .05f),
FloatNear(fg_rgb[2], .05f)));
EXPECT_NEAR(out_a, 1.0f, 1e-5);
}
TEST(AlphaTest, Mul) {
const float bg = 100;
const float fg = 25;
float out;
PerformMulBlending(&bg, &fg, &out, 1, /*clamp=*/false);
EXPECT_THAT(out, FloatNear(fg * bg, .05f));
PerformMulBlending(&bg, &fg, &out, 1, /*clamp=*/true);
EXPECT_THAT(out, FloatNear(bg, .05f));
}
TEST(AlphaTest, PremultiplyAndUnpremultiply) {
const float alpha[] = {0.f, 63.f / 255, 127.f / 255, 1.f};
float r[] = {120, 130, 140, 150};
float g[] = {124, 134, 144, 154};
float b[] = {127, 137, 147, 157};
PremultiplyAlpha(r, g, b, alpha, 4);
EXPECT_THAT(
r, ElementsAre(FloatNear(0.f, 1e-5f), FloatNear(130 * 63.f / 255, 1e-5f),
FloatNear(140 * 127.f / 255, 1e-5f), 150));
EXPECT_THAT(
g, ElementsAre(FloatNear(0.f, 1e-5f), FloatNear(134 * 63.f / 255, 1e-5f),
FloatNear(144 * 127.f / 255, 1e-5f), 154));
EXPECT_THAT(
b, ElementsAre(FloatNear(0.f, 1e-5f), FloatNear(137 * 63.f / 255, 1e-5f),
FloatNear(147 * 127.f / 255, 1e-5f), 157));
UnpremultiplyAlpha(r, g, b, alpha, 4);
EXPECT_THAT(r, ElementsAre(FloatNear(120, 1e-4f), FloatNear(130, 1e-4f),
FloatNear(140, 1e-4f), FloatNear(150, 1e-4f)));
EXPECT_THAT(g, ElementsAre(FloatNear(124, 1e-4f), FloatNear(134, 1e-4f),
FloatNear(144, 1e-4f), FloatNear(154, 1e-4f)));
EXPECT_THAT(b, ElementsAre(FloatNear(127, 1e-4f), FloatNear(137, 1e-4f),
FloatNear(147, 1e-4f), FloatNear(157, 1e-4f)));
}
TEST(AlphaTest, UnpremultiplyAndPremultiply) {
const float alpha[] = {0.f, 63.f / 255, 127.f / 255, 1.f};
float r[] = {50, 60, 70, 80};
float g[] = {54, 64, 74, 84};
float b[] = {57, 67, 77, 87};
UnpremultiplyAlpha(r, g, b, alpha, 4);
EXPECT_THAT(r, ElementsAre(_, FloatNear(60 * 255.f / 63, 1e-4f),
FloatNear(70 * 255.f / 127, 1e-4f), 80));
EXPECT_THAT(g, ElementsAre(_, FloatNear(64 * 255.f / 63, 1e-4f),
FloatNear(74 * 255.f / 127, 1e-4f), 84));
EXPECT_THAT(b, ElementsAre(_, FloatNear(67 * 255.f / 63, 1e-4f),
FloatNear(77 * 255.f / 127, 1e-4f), 87));
PremultiplyAlpha(r, g, b, alpha, 4);
EXPECT_THAT(r, ElementsAre(FloatNear(50, 1e-4f), FloatNear(60, 1e-4f),
FloatNear(70, 1e-4f), FloatNear(80, 1e-4f)));
EXPECT_THAT(g, ElementsAre(FloatNear(54, 1e-4f), FloatNear(64, 1e-4f),
FloatNear(74, 1e-4f), FloatNear(84, 1e-4f)));
EXPECT_THAT(b, ElementsAre(FloatNear(57, 1e-4f), FloatNear(67, 1e-4f),
FloatNear(77, 1e-4f), FloatNear(87, 1e-4f)));
}
} // namespace
} // namespace jxl
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