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Diffstat (limited to 'thirdparty/oidn/core/transfer_function.h')
| -rw-r--r-- | thirdparty/oidn/core/transfer_function.h | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/thirdparty/oidn/core/transfer_function.h b/thirdparty/oidn/core/transfer_function.h new file mode 100644 index 0000000000..35f2833092 --- /dev/null +++ b/thirdparty/oidn/core/transfer_function.h @@ -0,0 +1,201 @@ +// ======================================================================== // +// Copyright 2009-2019 Intel Corporation // +// // +// Licensed under the Apache License, Version 2.0 (the "License"); // +// you may not use this file except in compliance with the License. // +// You may obtain a copy of the License at // +// // +// http://www.apache.org/licenses/LICENSE-2.0 // +// // +// Unless required by applicable law or agreed to in writing, software // +// distributed under the License is distributed on an "AS IS" BASIS, // +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // +// See the License for the specific language governing permissions and // +// limitations under the License. // +// ======================================================================== // + +#pragma once + +#include "image.h" +#include "node.h" + +namespace oidn { + + __forceinline float luminance(float r, float g, float b) + { + return 0.212671f * r + 0.715160f * g + 0.072169f * b; + } + + // Color transfer function base class + class TransferFunction + { + public: + virtual ~TransferFunction() = default; + + virtual float forward(float y) const = 0; + virtual float inverse(float x) const = 0; + }; + + // HDR transfer function base class + class HDRTransferFunction : public TransferFunction + { + protected: + static constexpr float yMax = 65504.f; + + float exposure; + float rcpExposure; + + public: + HDRTransferFunction(float exposure = 1.f) + { + setExposure(exposure); + } + + void setExposure(float exposure) + { + this->exposure = exposure; + this->rcpExposure = (exposure != 0.f) ? (1.f / exposure) : 0.f; + } + }; + + // Linear transfer function (LDR) + class LinearTransferFunction : public TransferFunction + { + public: + __forceinline float forward(float y) const override + { + return min(y, 1.f); + } + + __forceinline float inverse(float x) const override + { + return min(x, 1.f); + } + }; + + // 2.2 gamma transfer function (LDR) + class GammaTransferFunction : public TransferFunction + { + public: + __forceinline float forward(float y) const override + { + return min(pow(y, 1.f/2.2f), 1.f); + } + + __forceinline float inverse(float x) const override + { + return min(pow(x, 2.2f), 1.f); + } + }; + + // Logarithmic transfer function (HDR) + // Compresses [0..65504] to [0..1] + class LogTransferFunction : public HDRTransferFunction + { + private: + static const float xScale; + + public: + LogTransferFunction(float exposure = 1.f) + : HDRTransferFunction(exposure) + { + } + + __forceinline float forward(float y) const override + { + return log(y * exposure + 1.f) * xScale; + } + + __forceinline float inverse(float x) const override + { + return (exp(x * (1.f/xScale)) - 1.f) * rcpExposure; + } + }; + + // PQX transfer function (HDR) + // Compresses [0..65504] to [0..1] + class PQXTransferFunction : public HDRTransferFunction + { + private: + static constexpr float m1 = 2610.f / 4096.f / 4.f; + static constexpr float m2 = 2523.f / 4096.f * 128.f; + static constexpr float c1 = 3424.f / 4096.f; + static constexpr float c2 = 2413.f / 4096.f * 32.f; + static constexpr float c3 = 2392.f / 4096.f * 32.f; + static constexpr float a = 3711.f / 4096.f / 8.f; + + static constexpr float yScale = 100.f / 10000.f; + static const float xScale; + + public: + PQXTransferFunction(float exposure = 1.f) + : HDRTransferFunction(exposure) + { + } + + __forceinline float forward(float y) const override + { + return pqxForward(y * exposure * yScale) * xScale; + } + + __forceinline float inverse(float x) const override + { + return pqxInverse(x * (1.f/xScale)) * (1.f/yScale) * rcpExposure; + } + + private: + static __forceinline float pqForward(float y) + { + const float yp = pow(y, m1); + return pow((c1 + c2 * yp) * rcp(1.f + c3 * yp), m2); + } + + static __forceinline float pqxForward(float y) + { + if (y <= 1.f) + return pqForward(y); + else + return a * log(y) + 1.f; + } + + static __forceinline float pqInverse(float x) + { + const float xp = pow(x, 1.f/m2); + return pow(max((xp - c1) * rcp(c2 - c3 * xp), 0.f), 1.f/m1); + } + + static __forceinline float pqxInverse(float x) + { + if (x <= 1.f) + return pqInverse(x); + else + return exp((x - 1.f) * (1.f/a)); + } + }; + + // Autoexposure node + class AutoexposureNode : public Node + { + private: + Image color; + std::shared_ptr<HDRTransferFunction> transferFunc; + + public: + AutoexposureNode(const Image& color, + const std::shared_ptr<HDRTransferFunction>& transferFunc) + : color(color), + transferFunc(transferFunc) + {} + + void execute(stream& sm) override + { + const float exposure = autoexposure(color); + //printf("exposure = %f\n", exposure); + transferFunc->setExposure(exposure); + } + + private: + static float autoexposure(const Image& color); + }; + +} // namespace oidn |