Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 131 insertions, 0 deletions

diff --git a/third_party/jpeg-xl/lib/jxl/cms/transfer_functions.h b/third_party/jpeg-xl/lib/jxl/cms/transfer_functions.h
new file mode 100644
index 0000000000..4e5273d5d3
--- /dev/null
+++ b/third_party/jpeg-xl/lib/jxl/cms/transfer_functions.h
@@ -0,0 +1,131 @@
+// 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.
+
+// Transfer functions for color encodings.
+
+#ifndef LIB_JXL_CMS_TRANSFER_FUNCTIONS_H_
+#define LIB_JXL_CMS_TRANSFER_FUNCTIONS_H_
+
+#include <algorithm>
+#include <cmath>
+
+#include "lib/jxl/base/status.h"
+
+namespace jxl {
+
+// Definitions for BT.2100-2 transfer functions (used inside/outside SIMD):
+// "display" is linear light (nits) normalized to [0, 1].
+// "encoded" is a nonlinear encoding (e.g. PQ) in [0, 1].
+// "scene" is a linear function of photon counts, normalized to [0, 1].
+
+// Despite the stated ranges, we need unbounded transfer functions: see
+// http://www.littlecms.com/CIC18_UnboundedCMM.pdf. Inputs can be negative or
+// above 1 due to chromatic adaptation. To avoid severe round-trip errors caused
+// by clamping, we mirror negative inputs via copysign (f(-x) = -f(x), see
+// https://developer.apple.com/documentation/coregraphics/cgcolorspace/1644735-extendedsrgb)
+// and extend the function domains above 1.
+
+// Hybrid Log-Gamma.
+class TF_HLG_Base {
+ public:
+  // EOTF. e = encoded.
+  static double DisplayFromEncoded(const double e) { return OOTF(InvOETF(e)); }
+
+  // Inverse EOTF. d = display.
+  static double EncodedFromDisplay(const double d) { return OETF(InvOOTF(d)); }
+
+ private:
+  // OETF (defines the HLG approach). s = scene, returns encoded.
+  static double OETF(double s) {
+    if (s == 0.0) return 0.0;
+    const double original_sign = s;
+    s = std::abs(s);
+
+    if (s <= kDiv12) return copysignf(std::sqrt(3.0 * s), original_sign);
+
+    const double e = kA * std::log(12 * s - kB) + kC;
+    JXL_ASSERT(e > 0.0);
+    return copysignf(e, original_sign);
+  }
+
+  // e = encoded, returns scene.
+  static double InvOETF(double e) {
+    if (e == 0.0) return 0.0;
+    const double original_sign = e;
+    e = std::abs(e);
+
+    if (e <= 0.5) return copysignf(e * e * (1.0 / 3), original_sign);
+
+    const double s = (std::exp((e - kC) * kRA) + kB) * kDiv12;
+    JXL_ASSERT(s >= 0);
+    return copysignf(s, original_sign);
+  }
+
+  // s = scene, returns display.
+  static double OOTF(const double s) {
+    // The actual (red channel) OOTF is RD = alpha * YS^(gamma-1) * RS, where
+    // YS = 0.2627 * RS + 0.6780 * GS + 0.0593 * BS. Let alpha = 1 so we return
+    // "display" (normalized [0, 1]) instead of nits. Our transfer function
+    // interface does not allow a dependency on YS. Fortunately, the system
+    // gamma at 334 nits is 1.0, so this reduces to RD = RS.
+    return s;
+  }
+
+  // d = display, returns scene.
+  static double InvOOTF(const double d) {
+    return d;  // see OOTF().
+  }
+
+ protected:
+  static constexpr double kA = 0.17883277;
+  static constexpr double kRA = 1.0 / kA;
+  static constexpr double kB = 1 - 4 * kA;
+  static constexpr double kC = 0.5599107295;
+  static constexpr double kDiv12 = 1.0 / 12;
+};
+
+// Perceptual Quantization
+class TF_PQ_Base {
+ public:
+  static double DisplayFromEncoded(float display_intensity_target, double e) {
+    if (e == 0.0) return 0.0;
+    const double original_sign = e;
+    e = std::abs(e);
+
+    const double xp = std::pow(e, 1.0 / kM2);
+    const double num = std::max(xp - kC1, 0.0);
+    const double den = kC2 - kC3 * xp;
+    JXL_DASSERT(den != 0.0);
+    const double d = std::pow(num / den, 1.0 / kM1);
+    JXL_DASSERT(d >= 0.0);  // Equal for e ~= 1E-9
+    return copysignf(d * (10000.0f / display_intensity_target), original_sign);
+  }
+
+  // Inverse EOTF. d = display.
+  static double EncodedFromDisplay(float display_intensity_target, double d) {
+    if (d == 0.0) return 0.0;
+    const double original_sign = d;
+    d = std::abs(d);
+
+    const double xp =
+        std::pow(d * (display_intensity_target * (1.0f / 10000.0f)), kM1);
+    const double num = kC1 + xp * kC2;
+    const double den = 1.0 + xp * kC3;
+    const double e = std::pow(num / den, kM2);
+    JXL_DASSERT(e > 0.0);
+    return copysignf(e, original_sign);
+  }
+
+ protected:
+  static constexpr double kM1 = 2610.0 / 16384;
+  static constexpr double kM2 = (2523.0 / 4096) * 128;
+  static constexpr double kC1 = 3424.0 / 4096;
+  static constexpr double kC2 = (2413.0 / 4096) * 32;
+  static constexpr double kC3 = (2392.0 / 4096) * 32;
+};
+
+}  // namespace jxl
+
+#endif  // LIB_JXL_CMS_TRANSFER_FUNCTIONS_H_