MLPAlgorithm PAD algorithm V1 version

This is an MLP based PAD algorithm.

bob/ip/pytorch_extractor/MLPAlgorithm.py

+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Created on Fri Aug 10 11:30:34 2018
+
+@author: Olegs Nikisins
+"""
+
+# =============================================================================
+# Import what is needed here:
+
+from bob.pad.base.algorithm import Algorithm
+
+from bob.bio.video.utils import FrameContainer
+
+import numpy as np
+
+from bob.ip.pytorch_extractor.utils import transform_and_net_forward
+
+
+
+# =============================================================================
+# Main body :
+
+class MLPAlgorithm(Algorithm):
+    """
+    This class is designed to apply a function from numpy to the input array
+    producing a single score.
+
+    Attributes
+    -----------
+    config_file: str
+        Relative name of the config file.
+        The path should be relative to ``config_group``,
+        for example: "!!!!!!!!!!!!!!!!! UPDATE !!!!!!!!!!!!!!!!!".
+
+        !!!!!!!!!!!!!!!!! UPDATE BELOW !!!!!!!!!!!!!!!!!
+
+        This file **must** contain at least the following definitions:
+
+        Function namely ``transform``, which is a  Compose transformation of
+        torchvision package, to be applied to the input samples.
+
+        A ``Network`` class, defining your network architecture. Note, if your
+        class is named differently, import it as ``Network``, for example:
+        ``from bob.learn.pytorch.architectures import MyNetwork as Network``
+
+        Optional: ``network_kwargs`` to be used for ``Network`` initialization.
+        For example, if you want to use the latent embeddings of the autoencoder
+        class, set the kwargs accodingly. Note: in current extractor the
+        ``forward()`` method of the ``Network`` is used for feature extraction.
+
+    config_group: str
+        Group/package name containing the configuration file. Usually all
+        configs should be stored in this folder/place.
+        For example: "bob.learn.pytorch.config".
+        Both ``config_file`` and ``config_group`` are used to access the
+        configuration module.
+
+    model_file : str
+        A paths to the model file to be used for network initialization.
+        The network structure is defined in the config file.
+
+    url : str
+        URL to download the pretrained models from.
+        If models are not available in the locations specified in the
+        ``model_file`` list, the system will try to download them from
+        ``url``. The downloaded models **will be placed to the locations**
+        specified in ``model_file`` list.
+
+        For example, the pretrained model for the MLP pre-trained on
+
+        !!!!!!!!!!!!!!!!! UPDATE HERE !!!!!!!!!!!!!!!!!
+
+        Default: None
+
+    archive_extension : str
+        Extension of the archived files to download from above ``urls``.
+        Default: '.tar.gz'
+
+    frame_level_scores_flag : bool
+        Return scores for each frame individually if True. Otherwise, return a
+        single score per video. Default: ``True``.
+    """
+
+    def __init__(self,
+                 config_file,
+                 config_group,
+                 model_file,
+                 url = None,
+                 archive_extension = '.tar.gz',
+                 frame_level_scores_flag = True):
+
+        super(MLPAlgorithm, self).__init__(config_file = config_file,
+                                           config_group = config_group,
+                                           model_file = model_file,
+                                           url = url,
+                                           archive_extension = archive_extension,
+                                           frame_level_scores_flag = frame_level_scores_flag)
+
+        self.config_file = config_file
+        self.config_group = config_group
+        self.model_file = model_file
+        self.url = url
+        self.archive_extension = archive_extension
+        self.frame_level_scores_flag = frame_level_scores_flag
+
+
+    # =========================================================================
+    def project(self, feature):
+        """
+        This function computes a vector of scores, one score for each sample
+        in the input array of features. The scores are computed applying
+        user defined function.
+
+        Set ``performs_projection = True`` in the constructor to enable this
+        function. It is assured that the :py:meth:`load_projector` was
+        **called before** the ``project`` function is executed.
+
+        **Parameters:**
+
+        ``feature`` : FrameContainer or :py:class:`numpy.ndarray`
+            Two types of inputs are accepted.
+            A Frame Container conteining the features of an individual frmaes,
+            see ``bob.bio.video.utils.FrameContainer``.
+            Or a ND feature array of the size (N_samples x dim1 x dim2 x ...).
+
+        **Returns:**
+
+        ``scores`` : 1D :py:class:`numpy.ndarray`
+            Vector of scores. Scores for the real class are expected to be
+            higher, than the scores of the negative / attack class.
+        """
+
+        # 1. Convert input array to numpy array if necessary.
+        if isinstance(
+                feature,
+                FrameContainer):  # if FrameContainer convert to 3D numpy array
+
+            feature = feature.as_array()
+
+        # kwargs for the transform_and_net_forward function:
+        function_kwargs = {}
+        function_kwargs["config_file"] = self.config_file
+        function_kwargs["config_group"] = self.config_group
+        function_kwargs["model_file"] = self.model_file
+        function_kwargs["color_input_flag"] = False
+
+        scores = transform_and_net_forward(feature = feature, **self.kwargs)
+
+        return scores
+
+
+    # =========================================================================
+    def score(self, toscore):
+        """
+        Returns a probability of a sample being a real class.
+
+        **Parameters:**
+
+        ``toscore`` : 1D :py:class:`numpy.ndarray`
+            Vector with scores for each frame/sample defining the probability
+            of the frame being a sample of the real class.
+
+        **Returns:**
+
+        ``score`` : [:py:class:`float`]
+            If ``frame_level_scores_flag = False`` a single score is returned.
+            One score per video. This score is placed into a list, because
+            the ``score`` must be an iterable.
+            Score is a probability of a sample being a real class.
+            If ``frame_level_scores_flag = True`` a list of scores is returned.
+            One score per frame/sample.
+        """
+
+        if self.frame_level_scores_flag:
+
+            score = list(toscore)
+
+        else:
+
+            score = [np.mean(toscore)]  # compute a single score per video
+
+        return score
+
+
+    # =========================================================================
+    def score_for_multiple_projections(self, toscore):
+        """
+        Returns a list of scores computed by the score method of this class.
+
+        **Parameters:**
+
+        ``toscore`` : 1D :py:class:`numpy.ndarray`
+            Vector with scores for each frame/sample defining the probability
+            of the frame being a sample of the real class.
+
+        **Returns:**
+
+        ``list_of_scores`` : [:py:class:`float`]
+            A list containing the scores.
+        """
+
+        scores = self.score(
+            toscore)  # returns float score or 1D array of scores
+
+        if isinstance(scores, np.float):  # if a single score
+
+            list_of_scores = [scores]
+
+        else:
+
+            list_of_scores = list(scores)
+
+        return list_of_scores
+