From cad231fbc79688c0309f96b9f5b2d3d9b9beeadd Mon Sep 17 00:00:00 2001
From: Guillaume HEUSCH <guillaume.heusch@idiap.ch>
Date: Fri, 23 Feb 2018 17:09:02 +0100
Subject: [PATCH] [extractor] added the extraction of the freq spectrum for
pulse signal
---
bob/pad/face/extractor/FrequencySpectrum.py | 77 +++++++++++++++++++++
bob/pad/face/extractor/__init__.py | 2 +
2 files changed, 79 insertions(+)
create mode 100644 bob/pad/face/extractor/FrequencySpectrum.py
diff --git a/bob/pad/face/extractor/FrequencySpectrum.py b/bob/pad/face/extractor/FrequencySpectrum.py
new file mode 100644
index 00000000..d22dcde0
--- /dev/null
+++ b/bob/pad/face/extractor/FrequencySpectrum.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python
+# encoding: utf-8
+
+import numpy
+
+from bob.bio.base.extractor import Extractor
+
+import logging
+logger = logging.getLogger("bob.pad.face")
+
+from scipy.signal import welch
+
+
+class FrequencySpectrum(Extractor, object):
+ """
+ Compute the Frequency Spectrum of the given signal.
+
+ The computation is made using Welch's algorithm.
+
+ **Parameters:**
+
+ framerate: int
+ The sampling frequency of the signal (i.e the framerate ...)
+
+ nsegments: int
+ Number of overlapping segments in Welch procedure
+
+ nfft: int
+ Number of points to compute the FFT
+
+ debug: boolean
+ Plot stuff
+ """
+ def __init__(self, framerate=25, nsegments=12, nfft=256, debug=False, **kwargs):
+
+ super(FrequencySpectrum, self).__init__()
+
+ self.framerate = framerate
+ self.nsegments = nsegments
+ self.nfft = nfft
+ self.debug = debug
+
+ def __call__(self, signal):
+ """
+ Compute the frequency spectrum for the given signal.
+
+ **Parameters:**
+
+ signal: numpy.array
+ The signal
+
+ **Returns:**
+
+ freq: numpy.array
+ the frequency spectrum
+ """
+ output_dim = int((self.nfft / 2) + 1)
+
+ # we have a single pulse signal
+ if signal.ndim == 1:
+ f, psd = welch(signal, self.framerate, nperseg=self.nsegments, nfft=self.nfft)
+
+ # we have 3 pulse signal (Li's preprocessing)
+ # in this case, return the signal corresponding to the green channel
+ if signal.ndim == 2 and (signal.shape[1] == 3):
+ psds = numpy.zeros((3, output_dim))
+ for i in range(3):
+ f, psds[i] = welch(signal[:, i], self.framerate, nperseg=self.nsegments, nfft=self.nfft)
+ psd = psds[1]
+
+ if self.debug:
+ from matplotlib import pyplot
+ pyplot.semilogy(f, psd, 'k')
+ pyplot.title('Power spectrum of the signal')
+ pyplot.show()
+
+ return psd
diff --git a/bob/pad/face/extractor/__init__.py b/bob/pad/face/extractor/__init__.py
index 310989b4..bd3f3bb2 100644
--- a/bob/pad/face/extractor/__init__.py
+++ b/bob/pad/face/extractor/__init__.py
@@ -5,6 +5,8 @@ from .VideoDataLoader import VideoDataLoader
from .VideoQualityMeasure import VideoQualityMeasure
from .FrameDiffFeatures import FrameDiffFeatures
+from .FrequencySpectrum import FrequencySpectrum
+
def __appropriate__(*args):
"""Says object was actually declared here, and not in the import module.
Fixing sphinx warnings of not being able to find classes, when path is
--
GitLab