noise.h (1442B)
1 // Copyright (c) the JPEG XL Project Authors. All rights reserved. 2 // 3 // Use of this source code is governed by a BSD-style 4 // license that can be found in the LICENSE file. 5 6 #ifndef LIB_JXL_NOISE_H_ 7 #define LIB_JXL_NOISE_H_ 8 9 // Noise parameters shared by encoder/decoder. 10 11 #include <stddef.h> 12 13 #include <algorithm> 14 #include <cmath> 15 #include <utility> 16 17 #include "lib/jxl/base/compiler_specific.h" 18 19 namespace jxl { 20 21 const float kNoisePrecision = 1 << 10; 22 23 struct NoiseParams { 24 // LUT index is an intensity of pixel / mean intensity of patch 25 static constexpr size_t kNumNoisePoints = 8; 26 float lut[kNumNoisePoints]; 27 28 void Clear() { 29 for (float& i : lut) i = 0.f; 30 } 31 bool HasAny() const { 32 for (float i : lut) { 33 if (std::abs(i) > 1e-3f) return true; 34 } 35 return false; 36 } 37 }; 38 39 static inline std::pair<int, float> IndexAndFrac(float x) { 40 constexpr size_t kScaleNumerator = NoiseParams::kNumNoisePoints - 2; 41 // TODO(user): instead of 1, this should be a proper Y range. 42 constexpr float kScale = kScaleNumerator / 1.0f; 43 float scaled_x = std::max(0.f, x * kScale); 44 float floor_x; 45 float frac_x = std::modf(scaled_x, &floor_x); 46 if (JXL_UNLIKELY(scaled_x >= kScaleNumerator + 1)) { 47 floor_x = kScaleNumerator; 48 frac_x = 1.f; 49 } 50 return std::make_pair(static_cast<int>(floor_x), frac_x); 51 } 52 53 struct NoiseLevel { 54 float noise_level; 55 float intensity; 56 }; 57 58 } // namespace jxl 59 60 #endif // LIB_JXL_NOISE_H_