1 files changed, 123 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/opsin_image_test.cc b/third_party/jpeg-xl/lib/jxl/opsin_image_test.cc
new file mode 100644
index 0000000000..07fd824f14
--- /dev/null
+++ b/third_party/jpeg-xl/lib/jxl/opsin_image_test.cc
@@ -0,0 +1,123 @@
+// 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 <stdio.h>
+
+#include <hwy/tests/test_util-inl.h>
+
+#include "lib/jxl/base/compiler_specific.h"
+#include "lib/jxl/color_management.h"
+#include "lib/jxl/dec_xyb.h"
+#include "lib/jxl/enc_color_management.h"
+#include "lib/jxl/enc_xyb.h"
+#include "lib/jxl/image.h"
+#include "lib/jxl/matrix_ops.h"
+#include "lib/jxl/opsin_params.h"
+
+namespace jxl {
+namespace {
+
+// Convert a single linear sRGB color to xyb, using the exact image conversion
+// procedure that jpeg xl uses.
+void LinearSrgbToOpsin(float rgb_r, float rgb_g, float rgb_b,
+                       float* JXL_RESTRICT xyb_x, float* JXL_RESTRICT xyb_y,
+                       float* JXL_RESTRICT xyb_b) {
+  Image3F linear(1, 1);
+  linear.PlaneRow(0, 0)[0] = rgb_r;
+  linear.PlaneRow(1, 0)[0] = rgb_g;
+  linear.PlaneRow(2, 0)[0] = rgb_b;
+
+  ImageMetadata metadata;
+  metadata.SetFloat32Samples();
+  metadata.color_encoding = ColorEncoding::LinearSRGB();
+  ImageBundle ib(&metadata);
+  ib.SetFromImage(std::move(linear), metadata.color_encoding);
+  Image3F opsin(1, 1);
+  (void)ToXYB(ib, /*pool=*/nullptr, &opsin, GetJxlCms());
+
+  *xyb_x = opsin.PlaneRow(0, 0)[0];
+  *xyb_y = opsin.PlaneRow(1, 0)[0];
+  *xyb_b = opsin.PlaneRow(2, 0)[0];
+}
+
+// Convert a single XYB color to linear sRGB, using the exact image conversion
+// procedure that jpeg xl uses.
+void OpsinToLinearSrgb(float xyb_x, float xyb_y, float xyb_b,
+                       float* JXL_RESTRICT rgb_r, float* JXL_RESTRICT rgb_g,
+                       float* JXL_RESTRICT rgb_b) {
+  Image3F opsin(1, 1);
+  opsin.PlaneRow(0, 0)[0] = xyb_x;
+  opsin.PlaneRow(1, 0)[0] = xyb_y;
+  opsin.PlaneRow(2, 0)[0] = xyb_b;
+  Image3F linear(1, 1);
+  OpsinParams opsin_params;
+  opsin_params.Init(/*intensity_target=*/255.0f);
+  OpsinToLinear(opsin, Rect(opsin), nullptr, &linear, opsin_params);
+  *rgb_r = linear.PlaneRow(0, 0)[0];
+  *rgb_g = linear.PlaneRow(1, 0)[0];
+  *rgb_b = linear.PlaneRow(2, 0)[0];
+}
+
+void OpsinRoundtripTestRGB(float r, float g, float b) {
+  float xyb_x, xyb_y, xyb_b;
+  LinearSrgbToOpsin(r, g, b, &xyb_x, &xyb_y, &xyb_b);
+  float r2, g2, b2;
+  OpsinToLinearSrgb(xyb_x, xyb_y, xyb_b, &r2, &g2, &b2);
+  EXPECT_NEAR(r, r2, 1e-3);
+  EXPECT_NEAR(g, g2, 1e-3);
+  EXPECT_NEAR(b, b2, 1e-3);
+}
+
+TEST(OpsinImageTest, VerifyOpsinAbsorbanceInverseMatrix) {
+  float matrix[9];  // writable copy
+  for (int i = 0; i < 9; i++) {
+    matrix[i] = GetOpsinAbsorbanceInverseMatrix()[i];
+  }
+  EXPECT_TRUE(Inv3x3Matrix(matrix));
+  for (int i = 0; i < 9; i++) {
+    EXPECT_NEAR(matrix[i], kOpsinAbsorbanceMatrix[i], 1e-6);
+  }
+}
+
+TEST(OpsinImageTest, OpsinRoundtrip) {
+  OpsinRoundtripTestRGB(0, 0, 0);
+  OpsinRoundtripTestRGB(1. / 255, 1. / 255, 1. / 255);
+  OpsinRoundtripTestRGB(128. / 255, 128. / 255, 128. / 255);
+  OpsinRoundtripTestRGB(1, 1, 1);
+
+  OpsinRoundtripTestRGB(0, 0, 1. / 255);
+  OpsinRoundtripTestRGB(0, 0, 128. / 255);
+  OpsinRoundtripTestRGB(0, 0, 1);
+
+  OpsinRoundtripTestRGB(0, 1. / 255, 0);
+  OpsinRoundtripTestRGB(0, 128. / 255, 0);
+  OpsinRoundtripTestRGB(0, 1, 0);
+
+  OpsinRoundtripTestRGB(1. / 255, 0, 0);
+  OpsinRoundtripTestRGB(128. / 255, 0, 0);
+  OpsinRoundtripTestRGB(1, 0, 0);
+}
+
+TEST(OpsinImageTest, VerifyZero) {
+  // Test that black color (zero energy) is 0,0,0 in xyb.
+  float x, y, b;
+  LinearSrgbToOpsin(0, 0, 0, &x, &y, &b);
+  EXPECT_NEAR(0, x, 1e-9);
+  EXPECT_NEAR(0, y, 1e-7);
+  EXPECT_NEAR(0, b, 1e-7);
+}
+
+TEST(OpsinImageTest, VerifyGray) {
+  // Test that grayscale colors have a fixed y/b ratio and x==0.
+  for (size_t i = 1; i < 255; i++) {
+    float x, y, b;
+    LinearSrgbToOpsin(i / 255., i / 255., i / 255., &x, &y, &b);
+    EXPECT_NEAR(0, x, 1e-6);
+    EXPECT_NEAR(kYToBRatio, b / y, 3e-5);
+  }
+}
+
+}  // namespace
+}  // namespace jxl