--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Core/DicomParsing/Internals/DicomImageDecoder.cpp	Tue Aug 29 21:17:35 2017 +0200
@@ -0,0 +1,817 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017 Osimis, 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 "../../PrecompiledHeaders.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 "../../Logging.h"
+#include "../../OrthancException.h"
+#include "../../Images/Image.h"
+#include "../../Images/ImageProcessing.h"
+#include "../../DicomFormat/DicomIntegerPixelAccessor.h"
+#include "../ToDcmtkBridge.h"
+#include "../FromDcmtkBridge.h"
+#include "../ParsedDicomFile.h"
+
+#if ORTHANC_ENABLE_PNG == 1
+#  include "../../Images/PngWriter.h"
+#endif
+
+#if ORTHANC_ENABLE_JPEG == 1
+#  include "../../Images/JpegWriter.h"
+#endif
+
+#include <boost/lexical_cast.hpp>
+
+#include <dcmtk/dcmdata/dcfilefo.h>
+#include <dcmtk/dcmdata/dcrleccd.h>
+#include <dcmtk/dcmdata/dcrlecp.h>
+
+#if ORTHANC_ENABLE_DCMTK_JPEG_LOSSLESS == 1
+#  include <dcmtk/dcmjpls/djcodecd.h>
+#  include <dcmtk/dcmjpls/djcparam.h>
+#  include <dcmtk/dcmjpeg/djrplol.h>
+#endif
+
+#if ORTHANC_ENABLE_DCMTK_JPEG == 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::ExtractDicomSummary(m, dataset);
+
+      /**
+       * 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::ExtractDicomSummary(m, dataset);
+
+    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_ENABLE_DCMTK_JPEG_LOSSLESS == 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_ENABLE_DCMTK_JPEG == 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,
+                                              bool invert)
+  {
+    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);
+
+      if (invert)
+      {
+        Orthanc::ImageProcessing::Invert(*image);
+      }
+    }
+    else
+    {
+      throw OrthancException(ErrorCode_NotImplemented);
+    }
+  }
+
+
+#if ORTHANC_ENABLE_PNG == 1
+  void DicomImageDecoder::ExtractPngImage(std::string& result,
+                                          std::auto_ptr<ImageAccessor>& image,
+                                          ImageExtractionMode mode,
+                                          bool invert)
+  {
+    ApplyExtractionMode(image, mode, invert);
+
+    PngWriter writer;
+    writer.WriteToMemory(result, *image);
+  }
+#endif
+
+
+#if ORTHANC_ENABLE_JPEG == 1
+  void DicomImageDecoder::ExtractJpegImage(std::string& result,
+                                           std::auto_ptr<ImageAccessor>& image,
+                                           ImageExtractionMode mode,
+                                           bool invert,
+                                           uint8_t quality)
+  {
+    if (mode != ImageExtractionMode_UInt8 &&
+        mode != ImageExtractionMode_Preview)
+    {
+      throw OrthancException(ErrorCode_ParameterOutOfRange);
+    }
+
+    ApplyExtractionMode(image, mode, invert);
+
+    JpegWriter writer;
+    writer.SetQuality(quality);
+    writer.WriteToMemory(result, *image);
+  }
+#endif
+}