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| invert_explicitly.cxx |
--- | --- | ---

Invert an image file (create a negative) by coding the loop explicitly
Usage: `invert_explicitly infile outfile`

    /************************************************************************/
    /*                                                                      */
    /*               Copyright 1998-2002 by Ullrich Koethe                  */
    /*       Cognitive Systems Group, University of Hamburg, Germany        */
    /*                                                                      */
    /*    This file is part of the VIGRA computer vision library.           */
    /*    ( Version 1.3.2, Jan 27 2005 )                                    */
    /*    You may use, modify, and distribute this software according       */
    /*    to the terms stated in the LICENSE file included in               */
    /*    the VIGRA distribution.                                           */
    /*                                                                      */
    /*    The VIGRA Website is                                              */
    /*        http://kogs-www.informatik.uni-hamburg.de/~koethe/vigra/      */
    /*    Please direct questions, bug reports, and contributions to        */
    /*        koethe@informatik.uni-hamburg.de                              */
    /*                                                                      */
    /*  THIS SOFTWARE IS PROVIDED AS IS AND WITHOUT ANY EXPRESS OR          */
    /*  IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED      */
    /*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */
    /*                                                                      */
    /************************************************************************/

    #include <iostream>
    #include "vigra/stdimage.hxx"
    #include "vigra/stdimagefunctions.hxx"
    #include "vigra/impex.hxx"

    using namespace vigra;

    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 in(info.width(), info.height());
                vigra::BImage out(info.width(), info.height());

                importImage(info, destImage(in));

                // create image iterator that points to upper left corner
                // of source image
                vigra::BImage::Iterator sy = in.upperLeft();

                // create image iterator that points past the lower right corner of
                // source image (similarly to the past-the-end iterator in the STL)
                vigra::BImage::Iterator send = in.lowerRight();

                // create image iterator that points to upper left corner
                // of destination image
                vigra::BImage::Iterator dy = out.upperLeft();

                // iterate down the first column of the images
                for(; sy.y != send.y; ++sy.y, ++dy.y)
                {
                    // create image iterator that points to the first
                    // pixel of the current row of the source image
                    vigra::BImage::Iterator sx = sy;

                    // create image iterator that points to the first
                    // pixel of the current row of the destination image
                    vigra::BImage::Iterator dx = dy;

                    // iterate across current row
                    for(; sx.x != send.x; ++sx.x, ++dx.x)
                    {
                        // calculate negative gray value
                        *dx = 255 - *sx;
                    }
                }

                exportImage(srcImageRange(out), vigra::ImageExportInfo(argv[2]));
            }
            else
            {
                vigra::BRGBImage in(info.width(), info.height());
                vigra::BRGBImage out(info.width(), info.height());

                importImage(info, destImage(in));

                vigra::RGBValue<int> offset(255, 255, 255);

                // create image iterator that points to upper left corner
                // of source image
                vigra::BRGBImage::Iterator sy = in.upperLeft();

                // create image iterator that points past the lower right corner of
                // source image (similarly to the past-the-end iterator in the STL)
                vigra::BRGBImage::Iterator send = in.lowerRight();

                // create image iterator that points to upper left corner
                // of destination image
                vigra::BRGBImage::Iterator dy = out.upperLeft();

                // iterate down the first column of the images
                for(; sy.y != send.y; ++sy.y, ++dy.y)
                {
                    // create image iterator that points to the first
                    // pixel of the current row of the source image
                    vigra::BRGBImage::Iterator sx = sy;

                    // create image iterator that points to the first
                    // pixel of the current row of the destination image
                    vigra::BRGBImage::Iterator dx = dy;

                    // iterate across current row
                    for(; sx.x != send.x; ++sx.x, ++dx.x)
                    {
                        // calculate negative color
                        *dx = offset - *sx;
                    }
                }

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

        return 0;
    }

© Ullrich Köthe (koethe@informatik.uni-hamburg.de) Cognitive Systems Group, University of Hamburg, Germany | html generated using doxygen and Python VIGRA 1.3.2 (27 Jan 2005)