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pyramid.cxx |

Reduce image size by mean of a Gaussian pyramid
Usage: `pyramid infile outfile`

    /************************************************************************/
    /*                                                                      */
    /*               Copyright 1998-2002 by Ullrich Koethe                  */
    /*                                                                      */
    /*    This file is part of the VIGRA computer vision library.           */
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    /*        ullrich.koethe@iwr.uni-heidelberg.de    or                    */
    /*        vigra@informatik.uni-hamburg.de                               */
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    #include <iostream>
    #include <stdio.h>
    #include "vigra/stdimage.hxx"
    #include "vigra/convolution.hxx"
    #include "vigra/resizeimage.hxx"
    #include "vigra/impex.hxx"

    using namespace vigra;

    // Gaussian reduction to next pyramid level
    template <class Image>
    void reduceToNextLevel(Image & in, Image & out)
    {
        // image size at current level
        int width = in.width();
        int height = in.height();

        // image size at next smaller level
        int newwidth = (width + 1) / 2;
        int newheight = (height + 1) / 2;

        // resize result image to appropriate size
        out.resize(newwidth, newheight);

        // define a Gaussian kernel (size 5x1)
        vigra::Kernel1D<double> filter;
        filter.initExplicitly(-2, 2) = 0.05, 0.25, 0.4, 0.25, 0.05;

        vigra::BasicImage<typename Image::value_type> tmpimage1(width, height);
        vigra::BasicImage<typename Image::value_type> tmpimage2(width, height);

        // smooth (band limit) input image
        separableConvolveX(srcImageRange(in),
                           destImage(tmpimage1), kernel1d(filter));
        separableConvolveY(srcImageRange(tmpimage1),
                           destImage(tmpimage2), kernel1d(filter));

        // downsample smoothed image
        resizeImageNoInterpolation(srcImageRange(tmpimage2), destImageRange(out));

    }

    int main(int argc, char ** argv)
    {
        if(argc != 3)
        {
            std::cout << "Usage: " << argv[0] << " infile outfile" << std::endl;
            std::cout << "(supported formats: " << vigra::impexListFormats() << ")" << std::endl;

            return 1;
        }

        try
        {
            vigra::ImageImportInfo info(argv[1]);

            if(info.isGrayscale())
            {
                vigra::BImage levels[4];

                levels[0].resize(info.width(), info.height());

                importImage(info, destImage(levels[0]));

                for(int i=1; i<4; ++i)
                {
                    // reduce gray image 3 times
                    reduceToNextLevel(levels[i-1], levels[i]);

                }

                exportImage(srcImageRange(levels[3]), vigra::ImageExportInfo(argv[2]));
            }
            else
            {
                vigra::BRGBImage levels[4];

                levels[0].resize(info.width(), info.height());

                importImage(info, destImage(levels[0]));

                for(int i=1; i<4; ++i)
                {
                    // reduce color image 3 times
                    reduceToNextLevel(levels[i-1], levels[i]);
                }

                exportImage(srcImageRange(levels[3]), vigra::ImageExportInfo(argv[2]));
            }
        }
        catch (vigra::StdException & e)
        {
            std::cout << e.what() << std::endl;
            return 1;
        }

        return 0;
    }

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python vigra 1.7.1 (3 Dec 2010)