codebase / stimlib

  #include <stim/image/image.h>
  #include <cmath>
  #include <stim/visualization/colormap.h>
  #include <stim/image/image_contour_detection.h>
  
  #define PI 3.1415926

  #define SIGMA_N 3

  
  void array_multiply(float* lhs, float rhs, unsigned int N);
  void array_add(float* ptr1, float* ptr2, float* sum, unsigned int N);
  void array_abs(float* img, unsigned int N);
  
  /// This function evaluates the center-surround(Laplacian of Gaussian) gaussian derivative gradient of an one-channel image
  
  /// @param img is the one-channel image
  /// @param r is an array of radii for different scaled discs(filters)
  /// @param sigma_n is the number of standard deviations used to define the sigma
  

  stim::image<float> laplacian_conv2(stim::image<float> image, int sigma){

  
  	unsigned int w = image.width();    // get the width of picture
  	unsigned int h = image.height();   // get the height of picture
  	unsigned N = w * h;				   // get the number of pixels of picture

  	
  	int winsize = 2 * SIGMA_N * sigma + 1;           // set the winsdow size of filter

  	stim::image<float> I(w, h, 1, 2);       // allocate space for return image of dG2_conv2

  	stim::image<float> Ixx(w, h);       // allocate space for Ixx
  	stim::image<float> Iyy(w, h);       // allocate space for Iyy

  	stim::image<float> laplacian(w, h);       // allocate space for Pb

  	I = dG2_conv2(image, sigma);  // calculate the Ixx, Iyy

  	Ixx = I.channel(0);
  	Iyy = I.channel(1);
  

  	array_add(Ixx.data(), Iyy.data(), laplacian.data(), N);				//laplacian = Ixx + Iyy;
  	array_abs(laplacian.data(), N);

  	//stim::cpu2image(laplacian.data(), "data_output/laplacian_0919.bmp", w, h, stim::cmBrewer); 

  	return laplacian;

  
  }