diff --git a/src/merge.cpp b/src/merge.cpp
index 7642977..f723393 100644
--- a/src/merge.cpp
+++ b/src/merge.cpp
@@ -377,18 +377,7 @@ std::pair<double, double> merge::getNoiseParams( int ISO, \
                                           double black_level ) 
 {
     double lambda_shot, lambda_read;
-    std::tie(lambda_shot, lambda_read) = burst_images.bayer_images[burst_images.reference_image_idx].get_noise_params();
-
-    // Obtain tiles
-    std::vector<cv::Mat> reference_tiles;
-    cv::Mat reference_image = burst_images.grayscale_images_pad[0];
-    std::cout << reference_image.rows << " " << reference_image.cols << std::endl;
-    for (int y = 0; y < reference_image.rows - 8; y += 8) {
-        for (int x = 0; x < reference_image.cols - 8; x += 8) {
-            cv::Mat tile = reference_image(cv::Rect(x, y, 16, 16));
-            reference_tiles.push_back(tile);
-        }
-    }
+    std::tie(lambda_shot, lambda_read) = merge::getNoiseParams(ISO, white_level, black_level);
 
     
 
@@ -400,4 +389,23 @@ std::pair<double, double> merge::getNoiseParams( int ISO, \
     // cv::imwrite("tile0.jpg", outputImg1);
 }
 
+std::pair<double, double> merge::getNoiseParams( int ISO, \
+                                          int white_level, \
+                                          double black_level ) 
+{
+    // Set ISO to 100 if not positive
+    ISO = ISO <= 0 ? 100 : ISO;
+
+    // Calculate shot noise and read noise parameters w.r.t ISO 100
+    double lambda_shot_p = ISO / 100.0f * baseline_lambda_shot;
+	double lambda_read_p = (ISO / 100.0f) * (ISO / 100.0f) * baseline_lambda_read;
+
+    // Rescale shot and read noise to normal range
+    double lambda_shot = lambda_shot_p * (white_level - black_level);
+    double lambda_read = lambda_read_p * (white_level - black_level) * (white_level - black_level);
+
+    // return pair
+    return std::make_pair(lambda_shot, lambda_read);
+}
+
 } // namespace hdrplus