code: def stretch_pattern(image_source):
      
      wsize, hsize = image_source.size;
      
      # Crop digit exactly
      (ws, hs, we, he) = gray_pattern_borders(image_source);
      image_source = image_source.crop((ws, hs, we, he));
      
      # Stretch it to initial sizes
      image_source = image_source.resize((wsize, hsize), Image.ANTIALIAS);
      
      # Transform image to simple array
      data = [pixel for pixel in image_source.getdata()];
      image_pattern = rgb2gray(data);
      
      return (image_pattern, image_source);
docs: !
      @brief Returns stretched content as 1-dimension (gray colored) matrix with size of input image.
      
      @param[in] image_source (Image): PIL Image instance.
      
      @return (list, Image) Stretched image as gray colored matrix and source image.