diff --git a/sigproc/inc/WireCellSigProc/ResponseShaper.h b/sigproc/inc/WireCellSigProc/ResponseShaper.h
new file mode 100644
index 00000000..253faefc
--- /dev/null
+++ b/sigproc/inc/WireCellSigProc/ResponseShaper.h
@@ -0,0 +1,62 @@
+/**
+ * Functions and classes for correcting response functions in-situ
+ */
+
+#ifndef WIRECELLSIGPROC_RESPONSESHAPER
+#define WIRECELLSIGPROC_RESPONSESHAPER
+
+#include "WireCellSigProc/Diagnostics.h"
+
+#include "WireCellIface/IChannelFilter.h"
+#include "WireCellIface/IConfigurable.h"
+#include "WireCellIface/IChannelNoiseDatabase.h"
+#include "WireCellIface/IAnodePlane.h"
+#include "WireCellIface/IDFT.h"
+
+#include "WireCellUtil/Waveform.h"
+#include "WireCellUtil/Bits.h"
+
+namespace WireCell {
+    namespace SigProc {
+        namespace ResponseShaper {
+
+            /**
+             * Correct variations in per-channel response
+             */
+            class OneChannelResponse : public WireCell::IChannelFilter, public WireCell::IConfigurable {
+               public:
+                OneChannelResponse(const std::string& anode_tn = "AnodePlane",
+                                const std::string& noisedb = "OmniChannelNoiseDB");
+                virtual ~OneChannelResponse();
+
+                // IChannelFilter interface
+
+                /** Filter in place the signal `sig` from given `channel`. */
+                virtual WireCell::Waveform::ChannelMaskMap apply(int channel, signal_t& sig) const;
+
+                /** Filter in place a group of signals together. */
+                virtual WireCell::Waveform::ChannelMaskMap apply(channel_signals_t& chansig) const;
+
+                void configure(const WireCell::Configuration& config);
+                WireCell::Configuration default_configuration() const;
+
+               private:
+                std::string m_elecresponse_tn{"ColdElec"};
+                std::string m_anode_tn, m_noisedb_tn;
+                IAnodePlane::pointer m_anode;
+                IChannelNoiseDatabase::pointer m_noisedb;
+                IDFT::pointer m_dft;
+            };
+
+        }  // namespace ResponseShaper
+
+    }  // namespace SigProc
+
+}  // namespace WireCell
+
+#endif
+
+// Local Variables:
+// mode: c++
+// c-basic-offset: 4
+// End:
diff --git a/sigproc/src/ResponseShaper.cxx b/sigproc/src/ResponseShaper.cxx
new file mode 100644
index 00000000..18e85e98
--- /dev/null
+++ b/sigproc/src/ResponseShaper.cxx
@@ -0,0 +1,127 @@
+/**
+ * A generic filter to correct reponse functions 
+ * Note: the purpose of this filter is not to replace the perchannel response
+ * correction in the OmnibusSigProc, instead it's implemented for validation purpose
+ */
+
+#include "WireCellSigProc/ResponseShaper.h"
+#include "WireCellSigProc/Derivations.h"
+
+#include "WireCellAux/DftTools.h"
+
+#include "WireCellUtil/NamedFactory.h"
+#include "WireCellUtil/Response.h"
+#include "WireCellIface/IChannelResponse.h"
+#include "WireCellIface/IWaveform.h"
+
+#include <cmath>
+#include <complex>
+#include <iostream>
+#include <set>
+
+WIRECELL_FACTORY(perChannelShaper, WireCell::SigProc::ResponseShaper::OneChannelResponse, WireCell::IChannelFilter,
+                 WireCell::IConfigurable)
+
+using namespace WireCell::SigProc;
+using WireCell::Aux::DftTools::fwd_r2c;
+using WireCell::Aux::DftTools::inv_c2r;
+
+
+ResponseShaper::OneChannelResponse::OneChannelResponse(const std::string& anode, const std::string& noisedb)
+  : m_anode_tn(anode)
+  , m_noisedb_tn(noisedb)
+{
+}
+ResponseShaper::OneChannelResponse::~OneChannelResponse() {}
+
+void ResponseShaper::OneChannelResponse::configure(const WireCell::Configuration& cfg)
+{
+    m_elecresponse_tn = get(cfg, "elecresponse", m_elecresponse_tn); 
+    m_anode_tn = get(cfg, "anode", m_anode_tn);
+    m_anode = Factory::find_tn<IAnodePlane>(m_anode_tn);
+    m_noisedb_tn = get(cfg, "noisedb", m_noisedb_tn);
+    m_noisedb = Factory::find_tn<IChannelNoiseDatabase>(m_noisedb_tn);
+
+    std::string dft_tn = get<std::string>(cfg, "dft", "FftwDFT");
+    m_dft = Factory::find_tn<IDFT>(dft_tn);
+}
+WireCell::Configuration ResponseShaper::OneChannelResponse::default_configuration() const
+{
+    Configuration cfg;
+    cfg["elecresponse"] = m_elecresponse_tn;
+    cfg["anode"] = m_anode_tn;
+    cfg["noisedb"] = m_noisedb_tn;
+    cfg["dft"] = "FftwDFT";     // type-name for the DFT to use
+    return cfg;
+}
+
+WireCell::Waveform::ChannelMaskMap ResponseShaper::OneChannelResponse::apply(int ch, signal_t& signal) const
+{
+    WireCell::Waveform::ChannelMaskMap ret;
+
+    // correct rc undershoot
+    auto spectrum = fwd_r2c(m_dft, signal);
+
+    // now apply the ch-by-ch response ...
+    auto cr = Factory::find_tn<IChannelResponse>("ParamsPerChannelResponse");
+    auto cr_bins = cr->channel_response_binning();
+    // if (cr_bins.binsize() != m_period) { // FIXME
+    //     THROW(ValueError() << errmsg{"ProtoduneHD::OneChannelResponse channel response size mismatch"});
+    // }
+    auto period = cr_bins.binsize();
+    WireCell::Binning tbins(signal.size(), cr_bins.min(), cr_bins.min() + signal.size() * period);
+
+    // Option 1: declare response function explicitly
+    // Response::ColdElec ce(14 * units::mV / units::fC, 2.2 * units::us);
+    // auto ewave = ce.generate(tbins);
+    
+    // Option 2: retrieve response function from configuration
+    auto elecresponse = Factory::find_tn<IWaveform>(m_elecresponse_tn);
+    auto ewave = elecresponse->waveform_samples(tbins);
+
+    const WireCell::Waveform::compseq_t elec = fwd_r2c(m_dft, ewave);
+
+    Waveform::realseq_t tch_resp = cr->channel_response(ch);
+    tch_resp.resize(signal.size(), 0);
+    const WireCell::Waveform::compseq_t ch_elec = fwd_r2c(m_dft, tch_resp);
+
+    for (unsigned int ind = 0; ind != elec.size(); ind ++) {
+        const auto four = ch_elec.at(ind);
+        if (std::abs(four) != 0) {
+            spectrum.at(ind) *= elec.at(ind) / four;
+        }
+        else {
+            spectrum.at(ind) = 0;
+        }
+    }
+
+
+    // remove the DC component
+    spectrum.front() = 0;
+    signal = inv_c2r(m_dft, spectrum);
+
+    // Now calculate the baseline ...
+    std::pair<double, double> temp = WireCell::Waveform::mean_rms(signal);
+    auto temp_signal = signal;
+    for (size_t i = 0; i != temp_signal.size(); i++) {
+        if (fabs(temp_signal.at(i) - temp.first) > 6 * temp.second) {
+            temp_signal.at(i) = temp.first;
+        }
+    }
+    float baseline = WireCell::Waveform::median_binned(temp_signal);
+    // correct baseline
+    WireCell::Waveform::increase(signal, baseline * (-1));
+
+
+    return ret;
+}
+
+WireCell::Waveform::ChannelMaskMap ResponseShaper::OneChannelResponse::apply(channel_signals_t& chansig) const
+{
+    return WireCell::Waveform::ChannelMaskMap();
+}
+
+// Local Variables:
+// mode: c++
+// c-basic-offset: 4
+// End: