ExampleImageDri.cpp

Creates a DRI image (dynamic range increase) out of three input images: normal exposure, under-exposed and over-exposed. THE INPUT IMAGES MUST BE GIVEN IN THIS ORDER!This algorithm is fairly simple: Iterate over all pixel of the normal exposed image. If the mean color value is below a threshold, take the pixel from the over-exposed image. If it is over a certain threshold, take it from the under-exposed image. To avoid sharp edges, a weighted sum is used. The weight results from the distance to the threshold. Both thresholds can be set, as well as the blending range.

Author

rwulff

/*
This file is part of the BIAS library (Basic ImageAlgorithmS).

Copyright (C) 2003-2009    (see file CONTACT for details)
  Multimediale Systeme der Informationsverarbeitung
  Institut fuer Informatik
  Christian-Albrechts-Universitaet Kiel


BIAS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.

BIAS 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with BIAS; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/


/**
 * @example ExampleImageDri.cpp
   @relates Image
   @brief Creates a DRI image (dynamic range increase) out of three input images:
 * normal exposure, under-exposed and over-exposed. THE INPUT IMAGES MUST
 * BE GIVEN IN THIS ORDER!
 *
 * This algorithm is fairly simple:
 * Iterate over all pixel of the normal exposed image. If the mean color value
 * is below a threshold, take the pixel from the over-exposed image. If it is
 * over a certain threshold, take it from the under-exposed image. To avoid
 * sharp edges, a weighted sum is used. The weight results from the distance
 * to the threshold.
 * Both thresholds can be set, as well as the blending range.
 *
 * @author rwulff
 */

#include <Base/Image/Image.hh>
#include <Base/Image/ImageIO.hh>
#include <Base/ImageUtils/ImageDraw.hh>


using namespace BIAS;
using namespace std;


int main(int argc, char *argv[]) {

  const unsigned char LO_THRESHOLD  = (unsigned char)100;
  const unsigned char HI_THRESHOLD = (unsigned char)230;

  // blend over a certain range:
  // 1.0 = whole range
  // 2.0 = 1/2 range
  // 3.0 = 1/3 range and so on...
  // e.g. if LO_THRESHOLD = 50 and BLENDING_RANGE = 2.0, intensities between
  // 25 (= 50 * 1/2.0) and 50 will be blended linearly
  const float BLENDING_RANGE = 1.0f;

  // check params
  if (argc < 4) {
    cout << "wrong parameter count!!" << endl << endl;
    cout << "usage:" << endl;
    cout << argv[0] << " " << "<normal_image> <darker_image> <brighter_image>" << endl;
    return -1;
  }

  // load images
  Image<unsigned char> imNorm, imDark, imBright;

  if (ImageIO::Load(argv[1], imNorm) != 0) {
    cout << "normal image could not be loaded!" << endl;
    return -1;
  }
  else {
    cout << "normal image loaded!" << endl;
  }
  if (ImageIO::Load(argv[2], imDark) != 0) {
    cout << "darker image could not be loaded!" << endl;
    return -1;
  }
  else {
    cout << "darker image loaded!" << endl;
  }
  if (ImageIO::Load(argv[3], imBright) != 0) {
    cout << "brighter image could not be loaded!" << endl;
    return -1;
  }
  else {
    cout << "brighter image loaded!" << endl;
  }

  cout << "images loaded" << endl;

  // ensure that input images have same size and RGB color model and init diffImage
  BIASASSERT(imNorm.GetWidth() == imDark.GetWidth() && imNorm.GetHeight() == imDark.GetHeight());
  BIASASSERT(imDark.GetWidth() == imBright.GetWidth() && imDark.GetHeight() == imBright.GetHeight());
  BIASASSERT(imNorm.GetColorModel() == ImageBase::CM_RGB);
  BIASASSERT(imDark.GetColorModel() == ImageBase::CM_RGB);
  BIASASSERT(imBright.GetColorModel() == ImageBase::CM_RGB);

  Image<unsigned char> imDri(imNorm);

  // get image data
  unsigned char *imNormData   = imNorm.GetImageData();
  unsigned char *imDarkData   = imDark.GetImageData();
  unsigned char *imBrightData = imBright.GetImageData();
  unsigned char *imDriData    = imDri.GetImageData();
  unsigned int offset = 0;
  unsigned char mean = 0;
  float weight = 0.0f;

  cout << "starting iteration..." << endl;

  // iterate over pixels and draw difference image
  for (unsigned int y = 0; y < imNorm.GetHeight(); y++) {
    for (unsigned int x = 0; x < imNorm.GetWidth(); x++) {
      offset = y*imNorm.GetWidth()*imNorm.GetChannelCount() + x*imNorm.GetChannelCount();

      mean = (imNormData[offset] + imNormData[offset+1] + imNormData[offset+2]) / 3;

      if (mean < LO_THRESHOLD) {
        weight = ((float)(LO_THRESHOLD - mean)) / (float)(LO_THRESHOLD);
        weight *= BLENDING_RANGE; // blend over a certain range
        weight = weight > 1.0f ? 1.0f : weight;
        imDriData[offset]   = (unsigned char)(weight*(float)imBrightData[offset]   + (1.0f-weight)*(float)imNormData[offset]);
        imDriData[offset+1] = (unsigned char)(weight*(float)imBrightData[offset+1] + (1.0f-weight)*(float)imNormData[offset+1]);
        imDriData[offset+2] = (unsigned char)(weight*(float)imBrightData[offset+2] + (1.0f-weight)*(float)imNormData[offset+2]);
      }
      else if (mean > HI_THRESHOLD) {
        weight = ((float)(mean - HI_THRESHOLD)) / (float)(255 - HI_THRESHOLD);
        weight *= BLENDING_RANGE; // blend over a certain range
        weight = weight > 1.0f ? 1.0f : weight;
        imDriData[offset]   = (unsigned char)(weight*(float)imDarkData[offset]   + (1.0f-weight)*(float)imNormData[offset]);
        imDriData[offset+1] = (unsigned char)(weight*(float)imDarkData[offset+1] + (1.0f-weight)*(float)imNormData[offset+1]);
        imDriData[offset+2] = (unsigned char)(weight*(float)imDarkData[offset+2] + (1.0f-weight)*(float)imNormData[offset+2]);
      }
      else {
        imDriData[offset]   = imNormData[offset];
        imDriData[offset+1] = imNormData[offset+1];
        imDriData[offset+2] = imNormData[offset+2];
      }
    }
  }

  ImageIO::Save("dri.mip", imDri);

  cout << "done!" << endl;

  return 0;
}