Function main

examples/tutorial.cpp:54–133

Main procedure ----------------

// Main procedure
//----------------
int main(int argc,char **argv) {

  // Define program usage and read command line parameters
  //-------------------------------------------------------

  // Display program usage, when invoked from the command line with option '-h'.
  cimg_usage("View the color profile of an image along the X axis");

  // Read image filename from the command line (or set it to "img/parrot.ppm" if option '-i' is not provided).
  const char* file_i = cimg_option("-i",cimg_imagepath "parrot.ppm","Input image");

  // Read pre-blurring variance from the command line (or set it to 1.0 if option '-blur' is not provided).
  const double sigma = cimg_option("-blur",1.0,"Variance of gaussian pre-blurring");

  // Init variables
  //----------------

  // Load an image, transform it to a color image (if necessary) and blur it with the standard deviation sigma.
  const CImg<unsigned char> image = CImg<>(file_i).normalize(0,255).blur((float)sigma).resize(-100,-100,1,3);

  // Create two display window, one for the image, the other for the color profile.
  CImgDisplay
    main_disp(image,"Color image (Try to move mouse pointer over)",0),
    draw_disp(500,400,"Color profile of the X-axis",0);

  // Define colors used to plot the profile, and a hatch to draw the vertical line
  unsigned int hatch = 0xF0F0F0F0;
  const unsigned char
    red[]   = { 255,0,0 },
    green[] = { 0,255,0 },
    blue [] = { 0,0,255 },
    black[] = { 0,0,0 };

    // Enter event loop. This loop ends when one of the two display window is closed or
    // when the keys 'ESC' or 'Q' are pressed.
    while (!main_disp.is_closed() && !draw_disp.is_closed() &&
           !main_disp.is_keyESC() && !draw_disp.is_keyESC() && !main_disp.is_keyQ() && !draw_disp.is_keyQ()) {

      // Handle display window resizing (if any)
      if (main_disp.is_resized()) main_disp.resize().display(image);
      draw_disp.resize();

      if (main_disp.mouse_x()>=0 && main_disp.mouse_y()>=0) { // Mouse pointer is over the image

        const int
          xm = main_disp.mouse_x(), // X-coordinate of the mouse pointer over the image
          ym = main_disp.mouse_y(), // Y-coordinate of the mouse pointer over the image
          xl = xm*draw_disp.width()/main_disp.width(), // Corresponding X-coordinate of the hatched line
          x = xm*image.width()/main_disp.width(), // Corresponding X-coordinate of the pointed pixel in the image
          y = ym*image.height()/main_disp.height(); // Corresponding Y-coordinate of the pointex pixel in the image

        // Retrieve color component values at pixel (x,y)
        const unsigned int
          val_red   = image(x,y,0),
          val_green = image(x,y,1),
          val_blue  = image(x,y,2);

        // Create and display the image of the intensity profile