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smooth_explicitly.cxx |

Smooth an image by averaging a 5x5-box (gray scale or color)
Usage: `smooth_explicitly infile outfile`

#include <iostream>
#include <vigra/multi_array.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: " << impexListFormats() << ")" << std::endl;
return 1;
}
try
{
// Read the header information of the input image.
ImageImportInfo info(argv[1]);
if (info.isGrayscale()) // Process grayscale image.
{
// Instantiate arrays of appropriate size for the original and smoothed image.
MultiArray<2, float> inputImage(info.shape()),
resultImage(info.shape());
// Read the input data.
importImage(info, inputImage);
// Smooth image by calculating the mean of a 5x5 window around each pixel.
Shape2 current; // the coordinate of the current pixel
for(current[1] = 0; current[1] < inputImage.shape(1); ++current[1])
{
for (current[0] = 0; current[0] < inputImage.shape(0); ++current[0])
{
// Compute the corners of the current smoothing window.
// Note:
// * Near the image border, not all pixels in a 5x5 window are within
// the image. The max() and min() operations make sure that the
// window is appropriately truncated (for example, max(Shape2(0), ...)
// sets negative coordinates to zero).
// * By convention, the lower right corner 'windowStop' must be outside the
// window. Therefore, we have to add 'Shape2(3)' (a vector of 3s) to 'current'.
// In contrast, the upper left corner 'windowStart' must be inside the window,
// so we only subtract 'Shape2(2)' (a vector of 2s) from 'current'.
Shape2 windowStart = max(Shape2(0), current - Shape2(2));
Shape2 windowStop = min(inputImage.shape(), current + Shape2(3));
// Create a view to the current window.
MultiArrayView<2, float> window = inputImage.subarray(windowStart, windowStop);
// Compute and store the average of the current window.
resultImage[current] = window.sum<float>() / window.size();
}
}
// Write the result image to the file given as second argument.
exportImage(resultImage, ImageExportInfo(argv[2]));
}
else // process color image
{
// Everything as before, but the pixel type is now RGBValue<float>
MultiArray<2, RGBValue<float> > inputImage(info.shape());
MultiArray<2, RGBValue<float> > resultImage(info.shape());
importImage(info, inputImage);
Shape2 current;
for(current[1] = 0; current[1] < inputImage.shape(1); ++current[1])
{
for (current[0] = 0; current[0] < inputImage.shape(0); ++current[0])
{
Shape2 windowStart = max(Shape2(0), current - Shape2(2));
Shape2 windowStop = min(inputImage.shape(), current + Shape2(3));
MultiArrayView<2, RGBValue<float> > window = inputImage.subarray(windowStart, windowStop);
resultImage[current] = window.sum<RGBValue<float> >() / window.size();
}
}
exportImage(resultImage, ImageExportInfo(argv[2]));
}
return 0;
}
catch (std::exception & e)
{
// Catch any errors that might have occurred and print their reason.
std::cout << e.what() << std::endl;
return 1;
}
}

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python vigra 1.11.0 (Fri May 19 2017)