diff --git a/brick/processing/frangi3-nt.so b/brick/processing/frangi3-nt.so
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diff --git a/image_verification.py b/image_verification.py
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+# Copyright CNRS/Inria/UNS
+# Contributor(s): Eric Debreuve (since 2019), Morgane Nadal (2020)
+#
+# eric.debreuve@cnrs.fr
+#
+# This software is governed by the CeCILL license under French law and
+# abiding by the rules of distribution of free software. You can use,
+# modify and/ or redistribute the software under the terms of the CeCILL
+# license as circulated by CEA, CNRS and INRIA at the following URL
+# "http://www.cecill.info".
+#
+# As a counterpart to the access to the source code and rights to copy,
+# modify and redistribute granted by the license, users are provided only
+# with a limited warranty and the software's author, the holder of the
+# economic rights, and the successive licensors have only limited
+# liability.
+#
+# In this respect, the user's attention is drawn to the risks associated
+# with loading, using, modifying and/or developing or reproducing the
+# software by the user in light of its specific status of free software,
+# that may mean that it is complicated to manipulate, and that also
+# therefore means that it is reserved for developers and experienced
+# professionals having in-depth computer knowledge. Users are therefore
+# encouraged to load and test the software's suitability as regards their
+# requirements in conditions enabling the security of their systems and/or
+# data to be ensured and, more generally, to use and operate it in the
+# same conditions as regards security.
+#
+# The fact that you are presently reading this means that you have had
+# knowledge of the CeCILL license and that you accept its terms.
+
+import sys as sy_
+from PySide2.QtWidgets import *
+import skimage.io as io_
+import matplotlib as mpl_
+import matplotlib.pyplot as pl_
+
+from brick.general.type import array_t
+
+mpl_.use('TkAgg')
+
+channel = 'G'
+data_path = 'data//DIO_6H_6_1.70bis_2.2_3.tif'
+image = io_.imread(data_path)
+
+
+class image_verification(QWidget):
+
+ def __init__(self, image: array_t, channel: str, parent=None):
+ super(image_verification, self).__init__(parent)
+ # Create widgets
+ # --Text
+ self.text0 = QLabel('The image input must not be constant.')
+ self.text1 = QLabel('The image has only one color channel.')
+ self.text2 = QLabel(f"The image has only 3 dimensions. However, a value for the 'channel' parameter"
+ f"is specified: {channel}. Continue with this image?")
+ self.text3 = QLabel(f"The image has multiple color channels. The channel {channel} is specified"
+ f" in the parameters. Continue with the resulting image?")
+ self.text4 = QLabel('The image has multiple color channels. Error in the value of the parameter channel.')
+ self.text5 = QLabel(f'The image dimensions are not correct: {image.ndim}, instead of 3 or 4.')
+ # --Buttons
+ self.button_quit = QPushButton("Quit and modify the parameters.")
+ self.button_continue = QPushButton("Continue.")
+ # Add button signal
+ self.button_continue.clicked.connect(self.Continue)
+ self.button_quit.clicked.connect(self.Quit)
+
+ if image is not None:
+ self.ImVerif(image, channel)
+
+ def Continue(self):
+ self.close()
+
+ def Quit(self):
+ sy_.exit(0)
+
+ def ImVerif(self, image: array_t, channel: str) -> array_t:
+ # The image must not be constant
+ if image.max() == image.min():
+ value_error = 'The image input must not be constant.'
+ print(value_error)
+
+ layout = QVBoxLayout()
+ layout.addWidget(self.text0)
+ layout.addWidget(self.button_quit)
+ self.setLayout(layout)
+
+ # Verification of the dimension of the image and its coherence with the parameters (channel)
+ elif image.ndim == 3:
+ print('The image has only one color channel.')
+ pl_.imshow(image[10, :, :])
+ pl_.show(block=True)
+
+ layout = QVBoxLayout()
+ layout.addWidget(self.text1)
+ layout.addWidget(self.button_continue)
+ self.setLayout(layout)
+
+ if channel is not None:
+ value_error = f'The image has only 3 dimensions. However, a value for the "channel" parameter is '
+ f'specified : {channel}. Give the channel the value None?'
+ print(value_error)
+
+ layout = QVBoxLayout()
+ layout.addWidget(self.text2)
+ layout.addWidget(self.button_continue)
+ layout.addWidget(self.button_quit)
+ self.setLayout(layout)
+
+ elif image.ndim == 4:
+ if channel == 'R' or channel == 'G' or channel == 'B':
+ # not changed into if --channel in 'RGB'-- because if channel='RG' => True.
+ value_error = f'The image has multiple color channels. The channel {channel} is specified in the ' \
+ f'parameters. '
+ print(value_error)
+
+ image = image[:, :, :, 'RGB'.find(channel)]
+ pl_.imshow(image[10, :, :])
+ pl_.show(block=True)
+
+ layout = QVBoxLayout()
+ layout.addWidget(self.text3)
+ layout.addWidget(self.button_continue)
+ layout.addWidget(self.button_quit)
+ self.setLayout(layout)
+
+ # TODO: Viewing bug when channel = 'R' or 'B'
+ # The obtained image must not be constant
+ if image.max() == image.min():
+ raise ValueError('The image input must not be constant.')
+
+ return image # TODO: How to return the image ??
+
+ else:
+ print('The image has multiple color channels. Error in the value of the parameter channel.')
+
+ layout = QVBoxLayout()
+ layout.addWidget(self.text4)
+ layout.addWidget(self.button_quit)
+ self.setLayout(layout)
+
+ elif image.ndim != 4 and image.ndim != 3:
+ print(f'The image dimensions are not correct: {image.ndim}, instead of 3 or 4.')
+
+ layout = QVBoxLayout()
+ layout.addWidget(self.text5)
+ layout.addWidget(self.button_quit)
+ self.setLayout(layout)
+
+
+if __name__ == '__main__':
+ # Create the Qt Application
+ app = QApplication(sy_.argv)
+ # Create and show the form
+ verif = image_verification(image, channel)
+ verif.show()
+
+ sy_.exit(app.exec_())
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