enc_adaptive_quantization.h

Enable keyboard shortcuts

// 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 <jxl/cms_interface.h>

#include "lib/jxl/base/data_parallel.h"

#include "lib/jxl/base/rect.h"

#include "lib/jxl/base/status.h"

#include "lib/jxl/enc_cache.h"

#include "lib/jxl/frame_header.h"

#include "lib/jxl/image.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;

class AcStrategyImage;

// 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.

StatusOr<ImageF> InitialQuantField(float butteraugli_target,

                                   const Image3F& opsin, const Rect& rect,

                                   ThreadPool* pool, float rescale,

                                   ImageF* initial_quant_mask,

                                   ImageF* initial_quant_mask1x1);

float InitialQuantDC(float butteraugli_target);

Status AdjustQuantField(const AcStrategyImage& ac_strategy, const Rect& rect,

                        float butteraugli_target, 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.

Status FindBestQuantizer(const FrameHeader& frame_header, const Image3F* linear,

                         const Image3F& opsin, ImageF& quant_field,

                         PassesEncoderState* enc_state,

                         const JxlCmsInterface& cms, ThreadPool* pool,

                         AuxOut* aux_out, double rescale = 1.0);

}  // namespace jxl

#endif  // LIB_JXL_ENC_ADAPTIVE_QUANTIZATION_H_