/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * In addition, as a special exception, the copyright holders of this
 * program give permission to link the code of its release with the
 * OpenSSL project's "OpenSSL" library (or with modified versions of it
 * that use the same license as the "OpenSSL" library), and distribute
 * the linked executables. You must obey the GNU General Public License
 * in all respects for all of the code used other than "OpenSSL". If you
 * modify file(s) with this exception, you may extend this exception to
 * your version of the file(s), but you are not obligated to do so. If
 * you do not wish to do so, delete this exception statement from your
 * version. If you delete this exception statement from all source files
 * in the program, then also delete it here.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/


#include "../PrecompiledHeadersServer.h"
#include "DicomImageDecoder.h"


/*=========================================================================

  This file is based on portions of the following project
  (cf. function "DecodePsmctRle1()"):

  Program: GDCM (Grassroots DICOM). A DICOM library
  Module:  http://gdcm.sourceforge.net/Copyright.html

  Copyright (c) 2006-2011 Mathieu Malaterre
  Copyright (c) 1993-2005 CREATIS
  (CREATIS = Centre de Recherche et d'Applications en Traitement de l'Image)
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.

  * Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

  * Neither name of Mathieu Malaterre, or CREATIS, nor the names of any
  contributors (CNRS, INSERM, UCB, Universite Lyon I), may be used to
  endorse or promote products derived from this software without specific
  prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

  =========================================================================*/


#include "../../Core/Logging.h"
#include "../../Core/OrthancException.h"
#include "../../Core/Images/Image.h"
#include "../../Core/Images/ImageProcessing.h"
#include "../../Core/Images/PngWriter.h"
#include "../../Core/Images/JpegWriter.h"
#include "../../Core/DicomFormat/DicomIntegerPixelAccessor.h"
#include "../ToDcmtkBridge.h"
#include "../FromDcmtkBridge.h"
#include "../ParsedDicomFile.h"
#include "../OrthancInitialization.h"

#include <boost/lexical_cast.hpp>

#include <dcmtk/dcmdata/dcfilefo.h>
#include <dcmtk/dcmdata/dcrleccd.h>
#include <dcmtk/dcmdata/dcrlecp.h>

#if ORTHANC_JPEG_LOSSLESS_ENABLED == 1
#  include <dcmtk/dcmjpls/djcodecd.h>
#  include <dcmtk/dcmjpls/djcparam.h>
#  include <dcmtk/dcmjpeg/djrplol.h>
#endif

#if ORTHANC_JPEG_ENABLED == 1
#  include <dcmtk/dcmjpeg/djcodecd.h>
#  include <dcmtk/dcmjpeg/djcparam.h>
#  include <dcmtk/dcmjpeg/djdecbas.h>
#  include <dcmtk/dcmjpeg/djdecext.h>
#  include <dcmtk/dcmjpeg/djdeclol.h>
#  include <dcmtk/dcmjpeg/djdecpro.h>
#  include <dcmtk/dcmjpeg/djdecsps.h>
#  include <dcmtk/dcmjpeg/djdecsv1.h>
#endif

#if DCMTK_VERSION_NUMBER <= 360
#  define EXS_JPEGProcess1      EXS_JPEGProcess1TransferSyntax
#  define EXS_JPEGProcess2_4    EXS_JPEGProcess2_4TransferSyntax
#  define EXS_JPEGProcess6_8    EXS_JPEGProcess6_8TransferSyntax
#  define EXS_JPEGProcess10_12  EXS_JPEGProcess10_12TransferSyntax
#  define EXS_JPEGProcess14     EXS_JPEGProcess14TransferSyntax
#  define EXS_JPEGProcess14SV1  EXS_JPEGProcess14SV1TransferSyntax
#endif

namespace Orthanc
{
  static const DicomTag DICOM_TAG_CONTENT(0x07a1, 0x100a);
  static const DicomTag DICOM_TAG_COMPRESSION_TYPE(0x07a1, 0x1011);


  bool DicomImageDecoder::IsPsmctRle1(DcmDataset& dataset)
  {
    DcmElement* e;
    char* c;

    // Check whether the DICOM instance contains an image encoded with
    // the PMSCT_RLE1 scheme.
    if (!dataset.findAndGetElement(ToDcmtkBridge::Convert(DICOM_TAG_COMPRESSION_TYPE), e).good() ||
        e == NULL ||
        !e->isaString() ||
        !e->getString(c).good() ||
        c == NULL ||
        strcmp("PMSCT_RLE1", c))
    {
      return false;
    }
    else
    {
      return true;
    }
  }


  bool DicomImageDecoder::DecodePsmctRle1(std::string& output,
                                          DcmDataset& dataset)
  {
    // Check whether the DICOM instance contains an image encoded with
    // the PMSCT_RLE1 scheme.
    if (!IsPsmctRle1(dataset))
    {
      return false;
    }

    // OK, this is a custom RLE encoding from Philips. Get the pixel
    // data from the appropriate private DICOM tag.
    Uint8* pixData = NULL;
    DcmElement* e;
    if (!dataset.findAndGetElement(ToDcmtkBridge::Convert(DICOM_TAG_CONTENT), e).good() ||
        e == NULL ||
        e->getUint8Array(pixData) != EC_Normal)
    {
      return false;
    }    

    // The "unsigned" below IS VERY IMPORTANT
    const uint8_t* inbuffer = reinterpret_cast<const uint8_t*>(pixData);
    const size_t length = e->getLength();

    /**
     * The code below is an adaptation of a sample code for GDCM by
     * Mathieu Malaterre (under a BSD license).
     * http://gdcm.sourceforge.net/html/rle2img_8cxx-example.html
     **/

    // RLE pass
    std::vector<uint8_t> temp;
    temp.reserve(length);
    for (size_t i = 0; i < length; i++)
    {
      if (inbuffer[i] == 0xa5)
      {
        temp.push_back(inbuffer[i+2]);
        for (uint8_t repeat = inbuffer[i + 1]; repeat != 0; repeat--)
        {
          temp.push_back(inbuffer[i+2]);
        }
        i += 2;
      }
      else
      {
        temp.push_back(inbuffer[i]);
      }
    }

    // Delta encoding pass
    uint16_t delta = 0;
    output.clear();
    output.reserve(temp.size());
    for (size_t i = 0; i < temp.size(); i++)
    {
      uint16_t value;

      if (temp[i] == 0x5a)
      {
        uint16_t v1 = temp[i + 1];
        uint16_t v2 = temp[i + 2];
        value = (v2 << 8) + v1;
        i += 2;
      }
      else
      {
        value = delta + (int8_t) temp[i];
      }

      output.push_back(value & 0xff);
      output.push_back(value >> 8);
      delta = value;
    }

    if (output.size() % 2)
    {
      output.resize(output.size() - 1);
    }

    return true;
  }


  class DicomImageDecoder::ImageSource
  {
  private:
    std::string psmct_;
    std::auto_ptr<DicomIntegerPixelAccessor> slowAccessor_;

  public:
    void Setup(DcmDataset& dataset,
               unsigned int frame)
    {
      psmct_.clear();
      slowAccessor_.reset(NULL);

      // See also: http://support.dcmtk.org/wiki/dcmtk/howto/accessing-compressed-data

      DicomMap m;
      FromDcmtkBridge::Convert(m, dataset, ORTHANC_MAXIMUM_TAG_LENGTH,
                               Configuration::GetDefaultEncoding());

      /**
       * Create an accessor to the raw values of the DICOM image.
       **/

      DcmElement* e;
      if (dataset.findAndGetElement(ToDcmtkBridge::Convert(DICOM_TAG_PIXEL_DATA), e).good() &&
          e != NULL)
      {
        Uint8* pixData = NULL;
        if (e->getUint8Array(pixData) == EC_Normal)
        {    
          slowAccessor_.reset(new DicomIntegerPixelAccessor(m, pixData, e->getLength()));
        }
      }
      else if (DecodePsmctRle1(psmct_, dataset))
      {
        LOG(INFO) << "The PMSCT_RLE1 decoding has succeeded";
        Uint8* pixData = NULL;
        if (psmct_.size() > 0)
        {
          pixData = reinterpret_cast<Uint8*>(&psmct_[0]);
        }

        slowAccessor_.reset(new DicomIntegerPixelAccessor(m, pixData, psmct_.size()));
      }
    
      if (slowAccessor_.get() == NULL)
      {
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      slowAccessor_->SetCurrentFrame(frame);
    }

    unsigned int GetWidth() const
    {
      assert(slowAccessor_.get() != NULL);
      return slowAccessor_->GetInformation().GetWidth();
    }

    unsigned int GetHeight() const
    {
      assert(slowAccessor_.get() != NULL);
      return slowAccessor_->GetInformation().GetHeight();
    }

    unsigned int GetChannelCount() const
    {
      assert(slowAccessor_.get() != NULL);
      return slowAccessor_->GetInformation().GetChannelCount();
    }

    const DicomIntegerPixelAccessor& GetAccessor() const
    {
      assert(slowAccessor_.get() != NULL);
      return *slowAccessor_;
    }

    unsigned int GetSize() const
    {
      assert(slowAccessor_.get() != NULL);
      return slowAccessor_->GetSize();
    }
  };


  ImageAccessor* DicomImageDecoder::CreateImage(DcmDataset& dataset,
                                                bool ignorePhotometricInterpretation)
  {
    DicomMap m;
    FromDcmtkBridge::Convert(m, dataset, ORTHANC_MAXIMUM_TAG_LENGTH,
                             Configuration::GetDefaultEncoding());

    DicomImageInformation info(m);
    PixelFormat format;
    
    if (!info.ExtractPixelFormat(format, ignorePhotometricInterpretation))
    {
      LOG(WARNING) << "Unsupported DICOM image: " << info.GetBitsStored() 
                   << "bpp, " << info.GetChannelCount() << " channels, " 
                   << (info.IsSigned() ? "signed" : "unsigned")
                   << (info.IsPlanar() ? ", planar, " : ", non-planar, ")
                   << EnumerationToString(info.GetPhotometricInterpretation())
                   << " photometric interpretation";
      throw OrthancException(ErrorCode_NotImplemented);
    }

    return new Image(format, info.GetWidth(), info.GetHeight(), false);
  }


  template <typename PixelType>
  static void CopyPixels(ImageAccessor& target,
                         const DicomIntegerPixelAccessor& source)
  {
    const PixelType minValue = std::numeric_limits<PixelType>::min();
    const PixelType maxValue = std::numeric_limits<PixelType>::max();

    for (unsigned int y = 0; y < source.GetInformation().GetHeight(); y++)
    {
      PixelType* pixel = reinterpret_cast<PixelType*>(target.GetRow(y));
      for (unsigned int x = 0; x < source.GetInformation().GetWidth(); x++)
      {
        for (unsigned int c = 0; c < source.GetInformation().GetChannelCount(); c++, pixel++)
        {
          int32_t v = source.GetValue(x, y, c);
          if (v < static_cast<int32_t>(minValue))
          {
            *pixel = minValue;
          }
          else if (v > static_cast<int32_t>(maxValue))
          {
            *pixel = maxValue;
          }
          else
          {
            *pixel = static_cast<PixelType>(v);
          }
        }
      }
    }
  }


  ImageAccessor* DicomImageDecoder::DecodeUncompressedImage(DcmDataset& dataset,
                                                            unsigned int frame)
  {
    ImageSource source;
    source.Setup(dataset, frame);


    /**
     * Resize the target image.
     **/

    std::auto_ptr<ImageAccessor> target(CreateImage(dataset, false));

    if (source.GetWidth() != target->GetWidth() ||
        source.GetHeight() != target->GetHeight())
    {
      throw OrthancException(ErrorCode_InternalError);
    }


    /**
     * If the format of the DICOM buffer is natively supported, use a
     * direct access to copy its values.
     **/

    const DicomImageInformation& info = source.GetAccessor().GetInformation();

    bool fastVersionSuccess = false;
    PixelFormat sourceFormat;
    if (!info.IsPlanar() &&
        info.ExtractPixelFormat(sourceFormat, false))
    {
      try
      {
        size_t frameSize = info.GetHeight() * info.GetWidth() * GetBytesPerPixel(sourceFormat);
        if ((frame + 1) * frameSize <= source.GetSize())
        {
          const uint8_t* buffer = reinterpret_cast<const uint8_t*>(source.GetAccessor().GetPixelData());

          ImageAccessor sourceImage;
          sourceImage.AssignReadOnly(sourceFormat, 
                                     info.GetWidth(), 
                                     info.GetHeight(),
                                     info.GetWidth() * GetBytesPerPixel(sourceFormat),
                                     buffer + frame * frameSize);

          ImageProcessing::Convert(*target, sourceImage);
          ImageProcessing::ShiftRight(*target, info.GetShift());
          fastVersionSuccess = true;
        }
      }
      catch (OrthancException&)
      {
        // Unsupported conversion, use the slow version
      }
    }

    /**
     * Slow version : loop over the DICOM buffer, storing its value
     * into the target image.
     **/

    if (!fastVersionSuccess)
    {
      switch (target->GetFormat())
      {
        case PixelFormat_RGB24:
        case PixelFormat_RGBA32:
        case PixelFormat_Grayscale8:
          CopyPixels<uint8_t>(*target, source.GetAccessor());
          break;
        
        case PixelFormat_Grayscale16:
          CopyPixels<uint16_t>(*target, source.GetAccessor());
          break;

        case PixelFormat_SignedGrayscale16:
          CopyPixels<int16_t>(*target, source.GetAccessor());
          break;

        default:
          throw OrthancException(ErrorCode_InternalError);
      }
    }

    return target.release();
  }


  ImageAccessor* DicomImageDecoder::ApplyCodec(const DcmCodec& codec,
                                               const DcmCodecParameter& parameters,
                                               DcmDataset& dataset,
                                               unsigned int frame)
  {
    DcmPixelSequence* pixelSequence = FromDcmtkBridge::GetPixelSequence(dataset);
    if (pixelSequence == NULL)
    {
      throw OrthancException(ErrorCode_BadFileFormat);
    }

    std::auto_ptr<ImageAccessor> target(CreateImage(dataset, true));

    Uint32 startFragment = 0;  // Default 
    OFString decompressedColorModel;  // Out
    DJ_RPLossless representationParameter;
    OFCondition c = codec.decodeFrame(&representationParameter, 
                                      pixelSequence, &parameters, 
                                      &dataset, frame, startFragment, target->GetBuffer(), 
                                      target->GetSize(), decompressedColorModel);

    if (c.good())
    {
      return target.release();    
    }
    else
    {
      LOG(ERROR) << "Cannot decode an image";
      throw OrthancException(ErrorCode_BadFileFormat);
    }
  }


  ImageAccessor* DicomImageDecoder::Decode(ParsedDicomFile& dicom,
                                           unsigned int frame)
  {
    DcmDataset& dataset = *dicom.GetDcmtkObject().getDataset();
    E_TransferSyntax syntax = dataset.getOriginalXfer();

    /**
     * Deal with uncompressed, raw images.
     * http://support.dcmtk.org/docs/dcxfer_8h-source.html
     **/
    if (syntax == EXS_Unknown ||
        syntax == EXS_LittleEndianImplicit ||
        syntax == EXS_BigEndianImplicit ||
        syntax == EXS_LittleEndianExplicit ||
        syntax == EXS_BigEndianExplicit)
    {
      return DecodeUncompressedImage(dataset, frame);
    }


#if ORTHANC_JPEG_LOSSLESS_ENABLED == 1
    /**
     * Deal with JPEG-LS images.
     **/

    if (syntax == EXS_JPEGLSLossless ||
        syntax == EXS_JPEGLSLossy)
    {
      DJLSCodecParameter parameters;
      std::auto_ptr<DJLSDecoderBase> decoder;

      switch (syntax)
      {
        case EXS_JPEGLSLossless:
          LOG(INFO) << "Decoding a JPEG-LS lossless DICOM image";
          decoder.reset(new DJLSLosslessDecoder);
          break;
          
        case EXS_JPEGLSLossy:
          LOG(INFO) << "Decoding a JPEG-LS near-lossless DICOM image";
          decoder.reset(new DJLSNearLosslessDecoder);
          break;

        default:
          throw OrthancException(ErrorCode_InternalError);
      }
    
      return ApplyCodec(*decoder, parameters, dataset, frame);
    }
#endif


#if ORTHANC_JPEG_ENABLED == 1
    /**
     * Deal with JPEG images.
     **/

    if (syntax == EXS_JPEGProcess1     ||  // DJDecoderBaseline
        syntax == EXS_JPEGProcess2_4   ||  // DJDecoderExtended
        syntax == EXS_JPEGProcess6_8   ||  // DJDecoderSpectralSelection (retired)
        syntax == EXS_JPEGProcess10_12 ||  // DJDecoderProgressive (retired)
        syntax == EXS_JPEGProcess14    ||  // DJDecoderLossless
        syntax == EXS_JPEGProcess14SV1)    // DJDecoderP14SV1
    {
      // http://support.dcmtk.org/docs-snapshot/djutils_8h.html#a2a9695e5b6b0f5c45a64c7f072c1eb9d
      DJCodecParameter parameters(
        ECC_lossyYCbCr,  // Mode for color conversion for compression, Unused for decompression
        EDC_photometricInterpretation,  // Perform color space conversion from YCbCr to RGB if DICOM photometric interpretation indicates YCbCr
        EUC_default,     // Mode for UID creation, unused for decompression
        EPC_default);    // Automatically determine whether color-by-plane is required from the SOP Class UID and decompressed photometric interpretation
      std::auto_ptr<DJCodecDecoder> decoder;

      switch (syntax)
      {
        case EXS_JPEGProcess1:
          LOG(INFO) << "Decoding a JPEG baseline (process 1) DICOM image";
          decoder.reset(new DJDecoderBaseline);
          break;
          
        case EXS_JPEGProcess2_4 :
          LOG(INFO) << "Decoding a JPEG baseline (processes 2 and 4) DICOM image";
          decoder.reset(new DJDecoderExtended);
          break;
          
        case EXS_JPEGProcess6_8:   // Retired
          LOG(INFO) << "Decoding a JPEG spectral section, nonhierarchical (processes 6 and 8) DICOM image";
          decoder.reset(new DJDecoderSpectralSelection);
          break;
          
        case EXS_JPEGProcess10_12:   // Retired
          LOG(INFO) << "Decoding a JPEG full progression, nonhierarchical (processes 10 and 12) DICOM image";
          decoder.reset(new DJDecoderProgressive);
          break;
          
        case EXS_JPEGProcess14:
          LOG(INFO) << "Decoding a JPEG lossless, nonhierarchical (process 14) DICOM image";
          decoder.reset(new DJDecoderLossless);
          break;
          
        case EXS_JPEGProcess14SV1:
          LOG(INFO) << "Decoding a JPEG lossless, nonhierarchical, first-order prediction (process 14 selection value 1) DICOM image";
          decoder.reset(new DJDecoderP14SV1);
          break;
          
        default:
          throw OrthancException(ErrorCode_InternalError);
      }
    
      return ApplyCodec(*decoder, parameters, dataset, frame);      
    }
#endif


    if (syntax == EXS_RLELossless)
    {
      LOG(INFO) << "Decoding a RLE lossless DICOM image";
      DcmRLECodecParameter parameters;
      DcmRLECodecDecoder decoder;
      return ApplyCodec(decoder, parameters, dataset, frame);
    }


    /**
     * This DICOM image format is not natively supported by
     * Orthanc. As a last resort, try and decode it through DCMTK by
     * converting its transfer syntax to Little Endian. This will
     * result in higher memory consumption. This is actually the
     * second example of the following page:
     * http://support.dcmtk.org/docs/mod_dcmjpeg.html#Examples
     **/
    
    {
      LOG(INFO) << "Decoding a compressed image by converting its transfer syntax to Little Endian";

      std::auto_ptr<DcmDataset> converted(dynamic_cast<DcmDataset*>(dataset.clone()));
      converted->chooseRepresentation(EXS_LittleEndianExplicit, NULL);

      if (converted->canWriteXfer(EXS_LittleEndianExplicit))
      {
        return DecodeUncompressedImage(*converted, frame);
      }
    }

    LOG(ERROR) << "Cannot decode a DICOM image with the built-in decoder";
    throw OrthancException(ErrorCode_BadFileFormat);
  }


  static bool IsColorImage(PixelFormat format)
  {
    return (format == PixelFormat_RGB24 ||
            format == PixelFormat_RGBA32);
  }


  bool DicomImageDecoder::TruncateDecodedImage(std::auto_ptr<ImageAccessor>& image,
                                               PixelFormat format,
                                               bool allowColorConversion)
  {
    // If specified, prevent the conversion between color and
    // grayscale images
    bool isSourceColor = IsColorImage(image->GetFormat());
    bool isTargetColor = IsColorImage(format);

    if (!allowColorConversion)
    {
      if (isSourceColor ^ isTargetColor)
      {
        return false;
      }
    }

    if (image->GetFormat() != format)
    {
      // A conversion is required
      std::auto_ptr<ImageAccessor> target(new Image(format, image->GetWidth(), image->GetHeight(), false));
      ImageProcessing::Convert(*target, *image);
      image = target;
    }

    return true;
  }


  bool DicomImageDecoder::PreviewDecodedImage(std::auto_ptr<ImageAccessor>& image)
  {
    switch (image->GetFormat())
    {
      case PixelFormat_RGB24:
      {
        // Directly return color images without modification (RGB)
        return true;
      }

      case PixelFormat_Grayscale8:
      case PixelFormat_Grayscale16:
      case PixelFormat_SignedGrayscale16:
      {
        // Grayscale image: Stretch its dynamics to the [0,255] range
        int64_t a, b;
        ImageProcessing::GetMinMaxValue(a, b, *image);

        if (a == b)
        {
          ImageProcessing::Set(*image, 0);
        }
        else
        {
          ImageProcessing::ShiftScale(*image, static_cast<float>(-a), 255.0f / static_cast<float>(b - a));
        }

        // If the source image is not grayscale 8bpp, convert it
        if (image->GetFormat() != PixelFormat_Grayscale8)
        {
          std::auto_ptr<ImageAccessor> target(new Image(PixelFormat_Grayscale8, image->GetWidth(), image->GetHeight(), false));
          ImageProcessing::Convert(*target, *image);
          image = target;
        }

        return true;
      }
      
      default:
        throw OrthancException(ErrorCode_NotImplemented);
    }
  }


  void DicomImageDecoder::ApplyExtractionMode(std::auto_ptr<ImageAccessor>& image,
                                              ImageExtractionMode mode)
  {
    if (image.get() == NULL)
    {
      throw OrthancException(ErrorCode_ParameterOutOfRange);
    }

    bool ok = false;

    switch (mode)
    {
      case ImageExtractionMode_UInt8:
        ok = TruncateDecodedImage(image, PixelFormat_Grayscale8, false);
        break;

      case ImageExtractionMode_UInt16:
        ok = TruncateDecodedImage(image, PixelFormat_Grayscale16, false);
        break;

      case ImageExtractionMode_Int16:
        ok = TruncateDecodedImage(image, PixelFormat_SignedGrayscale16, false);
        break;

      case ImageExtractionMode_Preview:
        ok = PreviewDecodedImage(image);
        break;

      default:
        throw OrthancException(ErrorCode_ParameterOutOfRange);
    }

    if (ok)
    {
      assert(image.get() != NULL);
    }
    else
    {
      throw OrthancException(ErrorCode_NotImplemented);
    }
  }


  void DicomImageDecoder::ExtractPngImage(std::string& result,
                                          std::auto_ptr<ImageAccessor>& image,
                                          ImageExtractionMode mode)
  {
    ApplyExtractionMode(image, mode);

    PngWriter writer;
    writer.WriteToMemory(result, *image);
  }


  void DicomImageDecoder::ExtractJpegImage(std::string& result,
                                           std::auto_ptr<ImageAccessor>& image,
                                           ImageExtractionMode mode,
                                           uint8_t quality)
  {
    if (mode != ImageExtractionMode_UInt8 &&
        mode != ImageExtractionMode_Preview)
    {
      throw OrthancException(ErrorCode_ParameterOutOfRange);
    }

    ApplyExtractionMode(image, mode);

    JpegWriter writer;
    writer.SetQuality(quality);
    writer.WriteToMemory(result, *image);
  }
}