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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 01:47:29 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 01:47:29 +0000
commit0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d (patch)
treea31f07c9bcca9d56ce61e9a1ffd30ef350d513aa /third_party/jpeg-xl/lib/jxl/transfer_functions-inl.h
parentInitial commit. (diff)
downloadfirefox-esr-0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d.tar.xz
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Adding upstream version 115.8.0esr.upstream/115.8.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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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.
+
+// Transfer functions for color encodings.
+
+#if defined(LIB_JXL_TRANSFER_FUNCTIONS_INL_H_) == defined(HWY_TARGET_TOGGLE)
+#ifdef LIB_JXL_TRANSFER_FUNCTIONS_INL_H_
+#undef LIB_JXL_TRANSFER_FUNCTIONS_INL_H_
+#else
+#define LIB_JXL_TRANSFER_FUNCTIONS_INL_H_
+#endif
+
+#include <algorithm>
+#include <cmath>
+#include <hwy/highway.h>
+
+#include "lib/jxl/base/compiler_specific.h"
+#include "lib/jxl/base/status.h"
+#include "lib/jxl/fast_math-inl.h"
+#include "lib/jxl/rational_polynomial-inl.h"
+
+HWY_BEFORE_NAMESPACE();
+namespace jxl {
+namespace HWY_NAMESPACE {
+
+// These templates are not found via ADL.
+using hwy::HWY_NAMESPACE::And;
+using hwy::HWY_NAMESPACE::AndNot;
+using hwy::HWY_NAMESPACE::Gt;
+using hwy::HWY_NAMESPACE::IfThenElse;
+using hwy::HWY_NAMESPACE::Lt;
+using hwy::HWY_NAMESPACE::Or;
+using hwy::HWY_NAMESPACE::Sqrt;
+using hwy::HWY_NAMESPACE::TableLookupBytes;
+
+// 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 {
+ public:
+ // EOTF. e = encoded.
+ JXL_INLINE double DisplayFromEncoded(const double e) const {
+ return OOTF(InvOETF(e));
+ }
+
+ // Inverse EOTF. d = display.
+ JXL_INLINE double EncodedFromDisplay(const double d) const {
+ return OETF(InvOOTF(d));
+ }
+
+ // Maximum error 5e-7.
+ template <class D, class V>
+ JXL_INLINE V EncodedFromDisplay(D d, V x) const {
+ const hwy::HWY_NAMESPACE::Rebind<uint32_t, D> du;
+ const V kSign = BitCast(d, Set(du, 0x80000000u));
+ const V original_sign = And(x, kSign);
+ x = AndNot(kSign, x); // abs
+ const V below_div12 = Sqrt(Mul(Set(d, 3.0f), x));
+ const V e =
+ MulAdd(Set(d, kA * 0.693147181f),
+ FastLog2f(d, MulAdd(Set(d, 12), x, Set(d, -kB))), Set(d, kC));
+ const V magnitude = IfThenElse(Le(x, Set(d, kDiv12)), below_div12, e);
+ return Or(AndNot(kSign, magnitude), original_sign);
+ }
+
+ private:
+ // OETF (defines the HLG approach). s = scene, returns encoded.
+ JXL_INLINE double OETF(double s) const {
+ 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.
+ JXL_INLINE double InvOETF(double e) const {
+ 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.
+ JXL_INLINE double OOTF(const double s) const {
+ // 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.
+ JXL_INLINE double InvOOTF(const double d) const {
+ return d; // see OOTF().
+ }
+
+ 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;
+};
+
+class TF_709 {
+ public:
+ JXL_INLINE double EncodedFromDisplay(const double d) const {
+ if (d < kThresh) return kMulLow * d;
+ return kMulHi * std::pow(d, kPowHi) + kSub;
+ }
+
+ // Maximum error 1e-6.
+ template <class D, class V>
+ JXL_INLINE V EncodedFromDisplay(D d, V x) const {
+ auto low = Mul(Set(d, kMulLow), x);
+ auto hi =
+ MulAdd(Set(d, kMulHi), FastPowf(d, x, Set(d, kPowHi)), Set(d, kSub));
+ return IfThenElse(Le(x, Set(d, kThresh)), low, hi);
+ }
+
+ template <class D, class V>
+ JXL_INLINE V DisplayFromEncoded(D d, V x) const {
+ auto low = Mul(Set(d, kInvMulLow), x);
+ auto hi = FastPowf(d, MulAdd(x, Set(d, kInvMulHi), Set(d, kInvAdd)),
+ Set(d, kInvPowHi));
+ return IfThenElse(Lt(x, Set(d, kInvThresh)), low, hi);
+ }
+
+ private:
+ static constexpr double kThresh = 0.018;
+ static constexpr double kMulLow = 4.5;
+ static constexpr double kMulHi = 1.099;
+ static constexpr double kPowHi = 0.45;
+ static constexpr double kSub = -0.099;
+
+ static constexpr double kInvThresh = 0.081;
+ static constexpr double kInvMulLow = 1 / 4.5;
+ static constexpr double kInvMulHi = 1 / 1.099;
+ static constexpr double kInvPowHi = 1 / 0.45;
+ static constexpr double kInvAdd = 0.099 * kInvMulHi;
+};
+
+// Perceptual Quantization
+class TF_PQ {
+ public:
+ // EOTF (defines the PQ approach). e = encoded.
+ JXL_INLINE double DisplayFromEncoded(double e) const {
+ 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, original_sign);
+ }
+
+ // Maximum error 3e-6
+ template <class D, class V>
+ JXL_INLINE V DisplayFromEncoded(D d, V x) const {
+ const hwy::HWY_NAMESPACE::Rebind<uint32_t, D> du;
+ const V kSign = BitCast(d, Set(du, 0x80000000u));
+ const V original_sign = And(x, kSign);
+ x = AndNot(kSign, x); // abs
+ // 4-over-4-degree rational polynomial approximation on x+x*x. This improves
+ // the maximum error by about 5x over a rational polynomial for x.
+ auto xpxx = MulAdd(x, x, x);
+ HWY_ALIGN constexpr float p[(4 + 1) * 4] = {
+ HWY_REP4(2.62975656e-04f), HWY_REP4(-6.23553089e-03f),
+ HWY_REP4(7.38602301e-01f), HWY_REP4(2.64553172e+00f),
+ HWY_REP4(5.50034862e-01f),
+ };
+ HWY_ALIGN constexpr float q[(4 + 1) * 4] = {
+ HWY_REP4(4.21350107e+02f), HWY_REP4(-4.28736818e+02f),
+ HWY_REP4(1.74364667e+02f), HWY_REP4(-3.39078883e+01f),
+ HWY_REP4(2.67718770e+00f),
+ };
+ auto magnitude = EvalRationalPolynomial(d, xpxx, p, q);
+ return Or(AndNot(kSign, magnitude), original_sign);
+ }
+
+ // Inverse EOTF. d = display.
+ JXL_INLINE double EncodedFromDisplay(double d) const {
+ if (d == 0.0) return 0.0;
+ const double original_sign = d;
+ d = std::abs(d);
+
+ const double xp = std::pow(d, 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);
+ }
+
+ // Maximum error 7e-7.
+ template <class D, class V>
+ JXL_INLINE V EncodedFromDisplay(D d, V x) const {
+ const hwy::HWY_NAMESPACE::Rebind<uint32_t, D> du;
+ const V kSign = BitCast(d, Set(du, 0x80000000u));
+ const V original_sign = And(x, kSign);
+ x = AndNot(kSign, x); // abs
+ // 4-over-4-degree rational polynomial approximation on x**0.25, with two
+ // different polynomials above and below 1e-4.
+ auto xto025 = Sqrt(Sqrt(x));
+ HWY_ALIGN constexpr float p[(4 + 1) * 4] = {
+ HWY_REP4(1.351392e-02f), HWY_REP4(-1.095778e+00f),
+ HWY_REP4(5.522776e+01f), HWY_REP4(1.492516e+02f),
+ HWY_REP4(4.838434e+01f),
+ };
+ HWY_ALIGN constexpr float q[(4 + 1) * 4] = {
+ HWY_REP4(1.012416e+00f), HWY_REP4(2.016708e+01f),
+ HWY_REP4(9.263710e+01f), HWY_REP4(1.120607e+02f),
+ HWY_REP4(2.590418e+01f),
+ };
+
+ HWY_ALIGN constexpr float plo[(4 + 1) * 4] = {
+ HWY_REP4(9.863406e-06f), HWY_REP4(3.881234e-01f),
+ HWY_REP4(1.352821e+02f), HWY_REP4(6.889862e+04f),
+ HWY_REP4(-2.864824e+05f),
+ };
+ HWY_ALIGN constexpr float qlo[(4 + 1) * 4] = {
+ HWY_REP4(3.371868e+01f), HWY_REP4(1.477719e+03f),
+ HWY_REP4(1.608477e+04f), HWY_REP4(-4.389884e+04f),
+ HWY_REP4(-2.072546e+05f),
+ };
+
+ auto magnitude = IfThenElse(Lt(x, Set(d, 1e-4f)),
+ EvalRationalPolynomial(d, xto025, plo, qlo),
+ EvalRationalPolynomial(d, xto025, p, q));
+ return Or(AndNot(kSign, magnitude), original_sign);
+ }
+
+ private:
+ 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;
+};
+
+// sRGB
+class TF_SRGB {
+ public:
+ template <typename V>
+ JXL_INLINE V DisplayFromEncoded(V x) const {
+ const HWY_FULL(float) d;
+ const HWY_FULL(uint32_t) du;
+ const V kSign = BitCast(d, Set(du, 0x80000000u));
+ const V original_sign = And(x, kSign);
+ x = AndNot(kSign, x); // abs
+
+ // TODO(janwas): range reduction
+ // Computed via af_cheb_rational (k=100); replicated 4x.
+ HWY_ALIGN constexpr float p[(4 + 1) * 4] = {
+ 2.200248328e-04f, 2.200248328e-04f, 2.200248328e-04f, 2.200248328e-04f,
+ 1.043637593e-02f, 1.043637593e-02f, 1.043637593e-02f, 1.043637593e-02f,
+ 1.624820318e-01f, 1.624820318e-01f, 1.624820318e-01f, 1.624820318e-01f,
+ 7.961564959e-01f, 7.961564959e-01f, 7.961564959e-01f, 7.961564959e-01f,
+ 8.210152774e-01f, 8.210152774e-01f, 8.210152774e-01f, 8.210152774e-01f,
+ };
+ HWY_ALIGN constexpr float q[(4 + 1) * 4] = {
+ 2.631846970e-01f, 2.631846970e-01f, 2.631846970e-01f,
+ 2.631846970e-01f, 1.076976492e+00f, 1.076976492e+00f,
+ 1.076976492e+00f, 1.076976492e+00f, 4.987528350e-01f,
+ 4.987528350e-01f, 4.987528350e-01f, 4.987528350e-01f,
+ -5.512498495e-02f, -5.512498495e-02f, -5.512498495e-02f,
+ -5.512498495e-02f, 6.521209011e-03f, 6.521209011e-03f,
+ 6.521209011e-03f, 6.521209011e-03f,
+ };
+ const V linear = Mul(x, Set(d, kLowDivInv));
+ const V poly = EvalRationalPolynomial(d, x, p, q);
+ const V magnitude =
+ IfThenElse(Gt(x, Set(d, kThreshSRGBToLinear)), poly, linear);
+ return Or(AndNot(kSign, magnitude), original_sign);
+ }
+
+ // Error ~5e-07
+ template <class D, class V>
+ JXL_INLINE V EncodedFromDisplay(D d, V x) const {
+ const hwy::HWY_NAMESPACE::Rebind<uint32_t, D> du;
+ const V kSign = BitCast(d, Set(du, 0x80000000u));
+ const V original_sign = And(x, kSign);
+ x = AndNot(kSign, x); // abs
+
+ // Computed via af_cheb_rational (k=100); replicated 4x.
+ HWY_ALIGN constexpr float p[(4 + 1) * 4] = {
+ -5.135152395e-04f, -5.135152395e-04f, -5.135152395e-04f,
+ -5.135152395e-04f, 5.287254571e-03f, 5.287254571e-03f,
+ 5.287254571e-03f, 5.287254571e-03f, 3.903842876e-01f,
+ 3.903842876e-01f, 3.903842876e-01f, 3.903842876e-01f,
+ 1.474205315e+00f, 1.474205315e+00f, 1.474205315e+00f,
+ 1.474205315e+00f, 7.352629620e-01f, 7.352629620e-01f,
+ 7.352629620e-01f, 7.352629620e-01f,
+ };
+ HWY_ALIGN constexpr float q[(4 + 1) * 4] = {
+ 1.004519624e-02f, 1.004519624e-02f, 1.004519624e-02f, 1.004519624e-02f,
+ 3.036675394e-01f, 3.036675394e-01f, 3.036675394e-01f, 3.036675394e-01f,
+ 1.340816930e+00f, 1.340816930e+00f, 1.340816930e+00f, 1.340816930e+00f,
+ 9.258482155e-01f, 9.258482155e-01f, 9.258482155e-01f, 9.258482155e-01f,
+ 2.424867759e-02f, 2.424867759e-02f, 2.424867759e-02f, 2.424867759e-02f,
+ };
+ const V linear = Mul(x, Set(d, kLowDiv));
+ const V poly = EvalRationalPolynomial(d, Sqrt(x), p, q);
+ const V magnitude =
+ IfThenElse(Gt(x, Set(d, kThreshLinearToSRGB)), poly, linear);
+ return Or(AndNot(kSign, magnitude), original_sign);
+ }
+
+ private:
+ static constexpr float kThreshSRGBToLinear = 0.04045f;
+ static constexpr float kThreshLinearToSRGB = 0.0031308f;
+ static constexpr float kLowDiv = 12.92f;
+ static constexpr float kLowDivInv = 1.0f / kLowDiv;
+};
+
+// Linear to sRGB conversion with error of at most 1.2e-4.
+template <typename D, typename V>
+V FastLinearToSRGB(D d, V v) {
+ const hwy::HWY_NAMESPACE::Rebind<uint32_t, D> du;
+ const hwy::HWY_NAMESPACE::Rebind<int32_t, D> di;
+ // Convert to 0.25 - 0.5 range.
+ auto v025_05 = BitCast(
+ d, And(Or(BitCast(du, v), Set(du, 0x3e800000)), Set(du, 0x3effffff)));
+ // third degree polynomial approximation between 0.25 and 0.5
+ // of 1.055/2^(7/2.4) * x^(1/2.4) * 0.5. A degree 4 polynomial only improves
+ // accuracy by about 3x.
+ auto d1 = MulAdd(v025_05, Set(d, 0.059914046f), Set(d, -0.108894556f));
+ auto d2 = MulAdd(d1, v025_05, Set(d, 0.107963754f));
+ auto pow = MulAdd(d2, v025_05, Set(d, 0.018092343f));
+ // Compute extra multiplier depending on exponent. Valid exponent range for
+ // [0.0031308f, 1.0) is 0...8 after subtracting 118.
+ // The next three constants contain a representation of the powers of
+ // 2**(1/2.4) = 2**(5/12) times two; in particular, bits from 26 to 31 are
+ // always the same and in k2to512powers_basebits, and the two arrays contain
+ // the next groups of 8 bits. This ends up being a 22-bit representation (with
+ // a mantissa of 13 bits). The choice of polynomial to approximate is such
+ // that the multiplication factor has the highest 5 bits constant, and that
+ // the factor for the lowest possible exponent is a power of two (thus making
+ // the additional bits 0, which is used to correctly merge back together the
+ // floats).
+ constexpr uint32_t k2to512powers_basebits = 0x40000000;
+ HWY_ALIGN constexpr uint8_t k2to512powers_25to18bits[16] = {
+ 0x0, 0xa, 0x19, 0x26, 0x32, 0x41, 0x4d, 0x5c,
+ 0x68, 0x75, 0x83, 0x8f, 0xa0, 0xaa, 0xb9, 0xc6,
+ };
+ HWY_ALIGN constexpr uint8_t k2to512powers_17to10bits[16] = {
+ 0x0, 0xb7, 0x4, 0xd, 0xcb, 0xe7, 0x41, 0x68,
+ 0x51, 0xd1, 0xeb, 0xf2, 0x0, 0xb7, 0x4, 0xd,
+ };
+ // Note that vld1q_s8_x2 on ARM seems to actually be slower.
+#if HWY_TARGET != HWY_SCALAR
+ using hwy::HWY_NAMESPACE::ShiftLeft;
+ using hwy::HWY_NAMESPACE::ShiftRight;
+ // Every lane of exp is now (if cast to byte) {0, 0, 0, <index for lookup>}.
+ auto exp = Sub(ShiftRight<23>(BitCast(di, v)), Set(di, 118));
+ auto pow25to18bits = TableLookupBytes(
+ LoadDup128(di,
+ reinterpret_cast<const int32_t*>(k2to512powers_25to18bits)),
+ exp);
+ auto pow17to10bits = TableLookupBytes(
+ LoadDup128(di,
+ reinterpret_cast<const int32_t*>(k2to512powers_17to10bits)),
+ exp);
+ // Now, pow* contain {0, 0, 0, <part of float repr of multiplier>}. Here
+ // we take advantage of the fact that each table has its position 0 equal to
+ // 0.
+ // We can now just reassemble the float.
+ auto mul = BitCast(
+ d, Or(Or(ShiftLeft<18>(pow25to18bits), ShiftLeft<10>(pow17to10bits)),
+ Set(di, k2to512powers_basebits)));
+#else
+ // Fallback for scalar.
+ uint32_t exp = ((BitCast(di, v).raw >> 23) - 118) & 0xf;
+ auto mul = BitCast(d, Set(di, (k2to512powers_25to18bits[exp] << 18) |
+ (k2to512powers_17to10bits[exp] << 10) |
+ k2to512powers_basebits));
+#endif
+ return IfThenElse(Lt(v, Set(d, 0.0031308f)), Mul(v, Set(d, 12.92f)),
+ MulAdd(pow, mul, Set(d, -0.055)));
+}
+
+// NOLINTNEXTLINE(google-readability-namespace-comments)
+} // namespace HWY_NAMESPACE
+} // namespace jxl
+HWY_AFTER_NAMESPACE();
+
+#endif // LIB_JXL_TRANSFER_FUNCTIONS_INL_H_