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Diffstat (limited to 'third_party/jpeg-xl/lib/jxl/quantizer.cc')
| -rw-r--r-- | third_party/jpeg-xl/lib/jxl/quantizer.cc | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/quantizer.cc b/third_party/jpeg-xl/lib/jxl/quantizer.cc new file mode 100644 index 0000000000..153cf19b21 --- /dev/null +++ b/third_party/jpeg-xl/lib/jxl/quantizer.cc @@ -0,0 +1,156 @@ +// 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 "lib/jxl/quantizer.h" + +#include <stdio.h> +#include <string.h> + +#include <algorithm> + +#include "lib/jxl/base/compiler_specific.h" +#include "lib/jxl/field_encodings.h" +#include "lib/jxl/fields.h" +#include "lib/jxl/image.h" +#include "lib/jxl/image_ops.h" +#include "lib/jxl/quant_weights.h" + +namespace jxl { + +static const int32_t kDefaultQuant = 64; + +constexpr int32_t Quantizer::kQuantMax; + +Quantizer::Quantizer(const DequantMatrices* dequant) + : Quantizer(dequant, kDefaultQuant, kGlobalScaleDenom / kDefaultQuant) {} + +Quantizer::Quantizer(const DequantMatrices* dequant, int quant_dc, + int global_scale) + : global_scale_(global_scale), quant_dc_(quant_dc), dequant_(dequant) { + JXL_ASSERT(dequant_ != nullptr); + RecomputeFromGlobalScale(); + inv_quant_dc_ = inv_global_scale_ / quant_dc_; + + memcpy(zero_bias_, kZeroBiasDefault, sizeof(kZeroBiasDefault)); +} + +void Quantizer::ComputeGlobalScaleAndQuant(float quant_dc, float quant_median, + float quant_median_absd) { + // Target value for the median value in the quant field. + const float kQuantFieldTarget = 5; + // We reduce the median of the quant field by the median absolute deviation: + // higher resolution on highly varying quant fields. + float scale = kGlobalScaleDenom * (quant_median - quant_median_absd) / + kQuantFieldTarget; + // Ensure that new_global_scale is positive and no more than 1<<15. + if (scale < 1) scale = 1; + if (scale > (1 << 15)) scale = 1 << 15; + int new_global_scale = static_cast<int>(scale); + // Ensure that quant_dc_ will always be at least + // 0.625 * kGlobalScaleDenom/kGlobalScaleNumerator = 10. + const int scaled_quant_dc = + static_cast<int>(quant_dc * kGlobalScaleNumerator * 1.6); + if (new_global_scale > scaled_quant_dc) { + new_global_scale = scaled_quant_dc; + if (new_global_scale <= 0) new_global_scale = 1; + } + global_scale_ = new_global_scale; + // Code below uses inv_global_scale_. + RecomputeFromGlobalScale(); + + float fval = quant_dc * inv_global_scale_ + 0.5f; + fval = std::min<float>(1 << 16, fval); + const int new_quant_dc = static_cast<int>(fval); + quant_dc_ = new_quant_dc; + + // quant_dc_ was updated, recompute values. + RecomputeFromGlobalScale(); +} + +void Quantizer::SetQuantFieldRect(const ImageF& qf, const Rect& rect, + ImageI* JXL_RESTRICT raw_quant_field) const { + for (size_t y = 0; y < rect.ysize(); ++y) { + const float* JXL_RESTRICT row_qf = rect.ConstRow(qf, y); + int32_t* JXL_RESTRICT row_qi = rect.Row(raw_quant_field, y); + for (size_t x = 0; x < rect.xsize(); ++x) { + int val = ClampVal(row_qf[x] * inv_global_scale_ + 0.5f); + row_qi[x] = val; + } + } +} + +void Quantizer::SetQuantField(const float quant_dc, const ImageF& qf, + ImageI* JXL_RESTRICT raw_quant_field) { + std::vector<float> data(qf.xsize() * qf.ysize()); + for (size_t y = 0; y < qf.ysize(); ++y) { + const float* JXL_RESTRICT row_qf = qf.Row(y); + for (size_t x = 0; x < qf.xsize(); ++x) { + float quant = row_qf[x]; + data[qf.xsize() * y + x] = quant; + } + } + std::nth_element(data.begin(), data.begin() + data.size() / 2, data.end()); + const float quant_median = data[data.size() / 2]; + std::vector<float> deviations(data.size()); + for (size_t i = 0; i < data.size(); i++) { + deviations[i] = fabsf(data[i] - quant_median); + } + std::nth_element(deviations.begin(), + deviations.begin() + deviations.size() / 2, + deviations.end()); + const float quant_median_absd = deviations[deviations.size() / 2]; + ComputeGlobalScaleAndQuant(quant_dc, quant_median, quant_median_absd); + if (raw_quant_field) { + JXL_CHECK(SameSize(*raw_quant_field, qf)); + SetQuantFieldRect(qf, Rect(qf), raw_quant_field); + } +} + +void Quantizer::SetQuant(float quant_dc, float quant_ac, + ImageI* JXL_RESTRICT raw_quant_field) { + ComputeGlobalScaleAndQuant(quant_dc, quant_ac, 0); + int32_t val = ClampVal(quant_ac * inv_global_scale_ + 0.5f); + FillImage(val, raw_quant_field); +} + +Status QuantizerParams::VisitFields(Visitor* JXL_RESTRICT visitor) { + JXL_QUIET_RETURN_IF_ERROR(visitor->U32( + BitsOffset(11, 1), BitsOffset(11, 2049), BitsOffset(12, 4097), + BitsOffset(16, 8193), 1, &global_scale)); + JXL_QUIET_RETURN_IF_ERROR(visitor->U32(Val(16), BitsOffset(5, 1), + BitsOffset(8, 1), BitsOffset(16, 1), 1, + &quant_dc)); + return true; +} + +QuantizerParams Quantizer::GetParams() const { + QuantizerParams params; + params.global_scale = global_scale_; + params.quant_dc = quant_dc_; + return params; +} + +Status Quantizer::Decode(BitReader* reader) { + QuantizerParams params; + JXL_RETURN_IF_ERROR(Bundle::Read(reader, ¶ms)); + global_scale_ = static_cast<int>(params.global_scale); + quant_dc_ = static_cast<int>(params.quant_dc); + RecomputeFromGlobalScale(); + return true; +} + +void Quantizer::DumpQuantizationMap(const ImageI& raw_quant_field) const { + printf("Global scale: %d (%.7f)\nDC quant: %d\n", global_scale_, + global_scale_ * 1.0 / kGlobalScaleDenom, quant_dc_); + printf("AC quantization Map:\n"); + for (size_t y = 0; y < raw_quant_field.ysize(); ++y) { + for (size_t x = 0; x < raw_quant_field.xsize(); ++x) { + printf(" %3d", raw_quant_field.Row(y)[x]); + } + printf("\n"); + } +} + +} // namespace jxl |