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diff --git a/third_party/jpeg-xl/lib/jxl/enc_adaptive_quantization.h b/third_party/jpeg-xl/lib/jxl/enc_adaptive_quantization.h
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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.
+
+#ifndef LIB_JXL_ENC_ADAPTIVE_QUANTIZATION_H_
+#define LIB_JXL_ENC_ADAPTIVE_QUANTIZATION_H_
+
+#include <stddef.h>
+
+#include "lib/jxl/ac_strategy.h"
+#include "lib/jxl/base/data_parallel.h"
+#include "lib/jxl/common.h"
+#include "lib/jxl/enc_cache.h"
+#include "lib/jxl/enc_params.h"
+#include "lib/jxl/frame_header.h"
+#include "lib/jxl/image.h"
+#include "lib/jxl/image_bundle.h"
+#include "lib/jxl/loop_filter.h"
+#include "lib/jxl/quant_weights.h"
+#include "lib/jxl/quantizer.h"
+#include "lib/jxl/splines.h"
+
+// Heuristics to find a good quantizer for a given image. InitialQuantField
+// produces a quantization field (i.e. relative quantization amounts for each
+// block) out of an opsin-space image. `InitialQuantField` uses heuristics,
+// `FindBestQuantizer` (in non-fast mode) will run multiple encoding-decoding
+// steps and try to improve the given quant field.
+
+namespace jxl {
+
+struct AuxOut;
+
+// Computes the decoded image for a given set of compression parameters. Mainly
+// used in the FindBestQuantization loops and in some tests.
+// TODO(veluca): this doesn't seem the best possible file for this function.
+ImageBundle RoundtripImage(const Image3F& opsin, PassesEncoderState* enc_state,
+                           const JxlCmsInterface& cms, ThreadPool* pool);
+
+// Returns an image subsampled by kBlockDim in each direction. If the value
+// at pixel (x,y) in the returned image is greater than 1.0, it means that
+// more fine-grained quantization should be used in the corresponding block
+// of the input image, while a value less than 1.0 indicates that less
+// fine-grained quantization should be enough. Returns a mask, too, which
+// can later be used to make better decisions about ac strategy.
+ImageF InitialQuantField(float butteraugli_target, const Image3F& opsin,
+                         const FrameDimensions& frame_dim, ThreadPool* pool,
+                         float rescale, ImageF* initial_quant_mask);
+
+float InitialQuantDC(float butteraugli_target);
+
+void AdjustQuantField(const AcStrategyImage& ac_strategy, const Rect& rect,
+                      ImageF* quant_field);
+
+// Returns a quantizer that uses an adjusted version of the provided
+// quant_field. Also computes the dequant_map corresponding to the given
+// dequant_float_map and chosen quantization levels.
+// `linear` is only used in Kitten mode or slower.
+void FindBestQuantizer(const ImageBundle* linear, const Image3F& opsin,
+                       PassesEncoderState* enc_state,
+                       const JxlCmsInterface& cms, ThreadPool* pool,
+                       AuxOut* aux_out, double rescale = 1.0);
+
+}  // namespace jxl
+
+#endif  // LIB_JXL_ENC_ADAPTIVE_QUANTIZATION_H_