diff --git a/include/aare/decode.hpp b/include/aare/decode.hpp
index 1c3c479..3e3f170 100644
--- a/include/aare/decode.hpp
+++ b/include/aare/decode.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstdint>
+#include <vector>
 #include <aare/NDView.hpp>
 namespace aare {
 
@@ -10,4 +11,16 @@ uint16_t adc_sar_04_decode64to16(uint64_t input);
 void adc_sar_05_decode64to16(NDView<uint64_t, 2> input, NDView<uint16_t,2> output);
 void adc_sar_04_decode64to16(NDView<uint64_t, 2> input, NDView<uint16_t,2> output);
 
+
+/**
+ * @brief Apply custom weights to a 16-bit input value. Will sum up weights[i]**i
+ * for each bit i that is set in the input value.
+ * @throws std::out_of_range if weights.size() < 16
+ * @param input 16-bit input value
+ * @param weights vector of weights, size must be less than or equal to 16
+ */
+double apply_custom_weights(uint16_t input, const NDView<double, 1> weights);
+
+void apply_custom_weights(NDView<uint16_t, 2> input, NDView<double, 2> output, const NDView<double, 1> weights);
+
 } // namespace aare
\ No newline at end of file
diff --git a/python/src/ctb_raw_file.hpp b/python/src/ctb_raw_file.hpp
index 56e571b..71af668 100644
--- a/python/src/ctb_raw_file.hpp
+++ b/python/src/ctb_raw_file.hpp
@@ -10,6 +10,8 @@
 #include "aare/decode.hpp"
 // #include "aare/fClusterFileV2.hpp"
 
+#include "np_helper.hpp"
+
 #include <cstdint>
 #include <filesystem>
 #include <pybind11/iostream.h>
@@ -65,6 +67,27 @@ m.def("adc_sar_04_decode64to16", [](py::array_t<uint8_t> input) {
     return output;
 });
 
+
+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");
+    }
+
+    // Create a 2D output array with the same shape as the input
+    std::vector<ssize_t> shape{input.shape(0), input.shape(1)};
+    py::array_t<double> output(shape);
+
+    auto weights_view = make_view_1d(weights);
+
+    // Create a view of the input and output arrays
+    NDView<uint16_t, 2> input_view(input.mutable_data(), {input.shape(0), input.shape(1)});
+    NDView<double, 2> output_view(output.mutable_data(), {output.shape(0), output.shape(1)});
+
+    apply_custom_weights(input_view, output_view, weights_view);
+
+    return output;
+});
+
  py::class_<CtbRawFile>(m, "CtbRawFile")
         .def(py::init<const std::filesystem::path &>())
         .def("read_frame",
diff --git a/src/decode.cpp b/src/decode.cpp
index 17c033d..f01f3b6 100644
--- a/src/decode.cpp
+++ b/src/decode.cpp
@@ -1,5 +1,5 @@
 #include "aare/decode.hpp"
-
+#include <cmath>
 namespace aare {
 
 uint16_t adc_sar_05_decode64to16(uint64_t input){
@@ -22,6 +22,10 @@ uint16_t adc_sar_05_decode64to16(uint64_t input){
 }
 
 void adc_sar_05_decode64to16(NDView<uint64_t, 2> input, NDView<uint16_t,2> output){
+    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) = adc_sar_05_decode64to16(input(i,j));
@@ -49,6 +53,9 @@ uint16_t adc_sar_04_decode64to16(uint64_t input){
 }
 
 void adc_sar_04_decode64to16(NDView<uint64_t, 2> input, NDView<uint16_t,2> output){
+    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) = adc_sar_04_decode64to16(input(i,j));
@@ -57,5 +64,30 @@ void adc_sar_04_decode64to16(NDView<uint64_t, 2> input, NDView<uint16_t,2> outpu
 }
 
 
+double apply_custom_weights(uint16_t input, const NDView<double, 1> weights) {
+    if(weights.size() > 16){
+        throw std::invalid_argument("weights size must be less than or equal to 16");
+    }
+
+    double result = 0.0;
+    for (ssize_t i = 0; i < weights.size(); ++i) {
+        result += ((input >> i) & 1) * std::pow(weights[i], i);
+    }
+    return result;
+
+}
+
+void apply_custom_weights(NDView<uint16_t, 2> input, NDView<double, 2> output, const NDView<double,1> weights) {
+    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);
+        }
+    }
+}
+
+
 
 } // namespace aare
diff --git a/src/decode.test.cpp b/src/decode.test.cpp
new file mode 100644
index 0000000..a90213c
--- /dev/null
+++ b/src/decode.test.cpp
@@ -0,0 +1,80 @@
+#include "aare/decode.hpp"
+
+#include <catch2/matchers/catch_matchers_floating_point.hpp>
+#include <catch2/catch_test_macros.hpp>
+#include "aare/NDArray.hpp"
+using Catch::Matchers::WithinAbs;
+#include <vector>
+
+TEST_CASE("test_adc_sar_05_decode64to16"){
+    uint64_t input = 0;
+    uint16_t output = aare::adc_sar_05_decode64to16(input);
+    CHECK(output == 0);
+
+
+    // bit 29 on th input is bit 0 on the output
+    input = 1UL << 29;
+    output = aare::adc_sar_05_decode64to16(input);
+    CHECK(output == 1);
+
+    // test all bits by iteratting through the bitlist
+    std::vector<int> bitlist = {29, 19, 28, 18, 31, 21, 27, 20, 24, 23, 25, 22};
+    for (size_t i = 0; i < bitlist.size(); i++) {
+        input = 1UL << bitlist[i];
+        output = aare::adc_sar_05_decode64to16(input);
+        CHECK(output == (1 << i));
+    }
+
+    
+    // test a few "random" values
+    input = 0;
+    input |= (1UL << 29);
+    input |= (1UL << 19);
+    input |= (1UL << 28);
+    output = aare::adc_sar_05_decode64to16(input);
+    CHECK(output == 7UL);
+
+
+    input = 0;
+    input |= (1UL << 18);
+    input |= (1UL << 27);
+    input |= (1UL << 25);
+    output = aare::adc_sar_05_decode64to16(input);
+    CHECK(output == 1096UL);
+
+    input = 0;
+    input |= (1UL << 25);
+    input |= (1UL << 22);
+    output = aare::adc_sar_05_decode64to16(input);
+    CHECK(output == 3072UL);
+ }
+
+
+ TEST_CASE("test_apply_custom_weights") {
+
+    uint16_t input = 1;
+    aare::NDArray<double, 1> weights_data({3}, 0.0);
+    weights_data(0) = 1.7;
+    weights_data(1) = 2.1;
+    weights_data(2) = 1.8;
+
+    auto weights = weights_data.view();
+
+
+    double output = aare::apply_custom_weights(input, weights);
+    CHECK_THAT(output, WithinAbs(1.0, 0.001));
+
+    input = 1UL << 1;
+    output = aare::apply_custom_weights(input, weights);
+    CHECK_THAT(output, WithinAbs(2.1, 0.001));
+
+
+    input = 1UL << 2;
+    output = aare::apply_custom_weights(input, weights);
+    CHECK_THAT(output, WithinAbs(3.24, 0.001));
+
+    input = 0b111;
+    output = aare::apply_custom_weights(input, weights);
+    CHECK_THAT(output, WithinAbs(6.34, 0.001));
+
+ }
\ No newline at end of file