diff --git a/python/src/ctb_raw_file.hpp b/python/src/ctb_raw_file.hpp
index 71af668..17da18e 100644
--- a/python/src/ctb_raw_file.hpp
+++ b/python/src/ctb_raw_file.hpp
@@ -68,7 +68,7 @@ m.def("adc_sar_04_decode64to16", [](py::array_t<uint8_t> input) {
 });
 
 
-m.def("apply_custom_weights", [](py::array_t<uint16_t> input, py::array_t<double> weights) {
+m.def("apply_custom_weights", [](py::array_t<uint16_t>& input, py::array_t<double>& weights) {
     if (input.ndim() != 2) {
         throw std::runtime_error("Only 2D arrays are supported at this moment");
     }
diff --git a/src/decode.cpp b/src/decode.cpp
index f01f3b6..fc0b5f6 100644
--- a/src/decode.cpp
+++ b/src/decode.cpp
@@ -81,9 +81,22 @@ void apply_custom_weights(NDView<uint16_t, 2> input, NDView<double, 2> output, c
     if(input.shape() != output.shape()){
         throw std::invalid_argument(LOCATION + " input and output shapes must match");
     }
-    for (int64_t i = 0; i < input.shape(0); i++) {
-        for (int64_t j = 0; j < input.shape(1); j++) {
-            output(i, j) = apply_custom_weights(input(i, j), weights);
+
+    //Calculate weights to avoid repeatedly calling std::pow
+    std::vector<double> weights_powers(weights.size());
+    for (ssize_t i = 0; i < weights.size(); ++i) {
+        weights_powers[i] = std::pow(weights[i], i);
+    }
+
+    // Apply custom weights to each element in the input array
+    for (ssize_t i = 0; i < input.shape(0); i++) {
+        for (ssize_t j = 0; j < input.shape(1); j++) {
+            
+            double result = 0.0;
+            for (ssize_t bit_index = 0; bit_index < weights_powers.size(); ++bit_index) {
+                result += ((input(i,j) >> bit_index) & 1) * weights_powers[bit_index];
+            }
+            output(i,j) = result;
         }
     }
 }