optimized difference computing

include/genimg/methods.hh

@@ -58,10 +58,6 @@ protected:
 private:
   // methods //////////////////////////////////////////////////////////////////
 
-  /// \brief Calculates the euclidian distance between two images
-  [[nodiscard]] auto euclidian_distance(cv::Mat const &t_img) const noexcept
-      -> double;
-
   /// \brief Creates and returns a random color
   [[nodiscard]] auto random_color() const noexcept;
 
@@ -119,8 +115,9 @@ private:
   mutable std::mutex
       colors_mutex_{}; /*!< Thread mutex for color set generation */
   std::string const output_path_{}; /*!< Write path for the generated image */
-  double diff_{euclidian_distance(generated_image_)}; /*!< Euclidian difference
-                         between \ref reference_ and \ref generated_image_ */
+  double diff_{
+      cv::norm(reference_, generated_image_)}; /*!< Euclidian difference
+                between \ref reference_ and \ref generated_image_ */
   int const total_iterations_{0}; /*!< Number of iterations to perform */
   int remaining_iter_{
       total_iterations_}; /*!< Remaining iterations to perform */