ENH: Add 1D FFT Example

src/Filtering/FFT/CMakeLists.txt

@@ -1,4 +1,17 @@
-add_example(FilterImageInFourierDomain)
+add_example(ComputeFFTInOneDimension)
+compare_to_baseline(
+  PYTHON_ONLY
+  EXAMPLE_NAME ComputeFFTInOneDimension
+  TEST_NAME ComputeFFTInOneDimensionModulusBaselineComparison
+  BASELINE_PREFIX MouseLiver1DFFTModulusOutputBaseline
+)
+compare_to_baseline(
+  PYTHON_ONLY
+  EXAMPLE_NAME ComputeFFTInOneDimension
+  TEST_NAME ComputeFFTInOneDimensionPhaseBaselineComparison
+  BASELINE_PREFIX MouseLiver1DFFTPhaseOutputBaseline
+)
+
 compare_to_baseline(
   EXAMPLE_NAME FilterImageInFourierDomain
   BASELINE_PREFIX OutputBaseline

src/Filtering/FFT/ComputeFFTInOneDimension/CMakeLists.txt

@@ -0,0 +1,23 @@
+cmake_minimum_required(VERSION 3.16.3)
+
+project(ComputeFFTInOneDimension)
+
+find_package(ITK REQUIRED)
+include(${ITK_USE_FILE})
+
+install(FILES Code.py CMakeLists.txt
+  DESTINATION share/ITKSphinxExamples/Code/Filtering/FFT/ComputeFFTInOneDimension
+  COMPONENT Code
+  )
+
+enable_testing()
+
+if(ITK_WRAP_PYTHON)
+  find_package(PythonInterp REQUIRED)
+  add_test(NAME ComputeFFTInOneDimensionPython
+    COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/Code.py
+      ${CMAKE_CURRENT_BINARY_DIR}/MouseLiverRF.mha
+      ${CMAKE_CURRENT_BINARY_DIR}/MouseLiver1DFFTModulusOutputPython.mha
+      ${CMAKE_CURRENT_BINARY_DIR}/MouseLiver1DFFTPhaseOutputPython.mha
+  )
+endif()

src/Filtering/FFT/ComputeFFTInOneDimension/Code.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python
+
+# Copyright NumFOCUS
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0.txt
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import itk
+import argparse
+
+parser = argparse.ArgumentParser(description="Compute Inverse FFT Of Image.")
+parser.add_argument("input_path", nargs=1, type=str)
+parser.add_argument("modulus_output_path", nargs=1, type=str)
+parser.add_argument("phase_output_path", nargs=1, type=str)
+parser.add_argument("fft_direction", nargs="?", default=0, type=int)
+args = parser.parse_args()
+
+# Read input image
+pixel_type = itk.F
+image = itk.imread(args.input_path[0], pixel_type=pixel_type)
+print(f"Read real input image of type {type(image)} and size {itk.size(image)}")
+
+assert (
+    args.fft_direction < image.GetImageDimension()
+), "FFT direction must be an image dimension"
+
+# Perform FFT in given direction
+padded_image = itk.fft_pad_image_filter(image)
+print(f"Padded input image to size {itk.size(image)}")
+print(f"Performing FFT along axis {args.fft_direction}")
+complex_image = itk.forward1_dfft_image_filter(image, direction=args.fft_direction)
+print(
+    f"Generated complex frequency image of type {type(complex_image)} and size {itk.size(complex_image)}"
+)
+
+# Shift image along FFT dimension to represent complex range (-f_B, +f_B]
+shift = [0] * complex_image.GetImageDimension()
+shift[args.fft_direction] = int(itk.size(complex_image)[args.fft_direction] / 2)
+shift = [int(itk.size(complex_image)[args.fft_direction] / 2), 0]
+shifted_image = itk.cyclic_shift_image_filter(complex_image, shift=shift)
+
+# Write out modulus and phase images for visualization in PNG format
+modulus_image = itk.complex_to_modulus_image_filter(shifted_image)
+itk.imwrite(modulus_image, args.modulus_output_path[0])
+
+phase_image = itk.complex_to_phase_image_filter(shifted_image)
+itk.imwrite(phase_image, args.phase_output_path[0])

src/Filtering/FFT/ComputeFFTInOneDimension/Documentation.rst

@@ -0,0 +1,71 @@
+:name: ComputeFFTInOneDimension
+
+Compute Forward FFT In One Dimension
+====================================
+
+.. index::
+   single: Forward1DFFTImageFilter
+   single: ComplexToRealImageFilter
+   single: ComplexToImaginaryImageFilter
+   single: ComplexToModulusImageFilter
+   single: CyclicShiftImageFilter
+   single: ImageFileReader
+   single: ImageFileWriter
+
+Synopsis
+--------
+
+Compute forward FFT of an image in one dimension.
+
+
+Results
+-------
+
+.. figure:: MouseLiverRF.png
+  :scale: 50%
+  :alt: Input image
+
+  Input RF Ultrasound Image
+
+.. figure:: MouseLiverModulusOutput.png
+  :scale: 50%
+  :alt: Modulus Image
+
+  Output Modulus Image
+
+.. figure:: MouseLiverPhaseOutput.png
+  :scale: 50%
+  :alt: Phase Image
+
+  Output Phase Image
+
+Output::
+
+  Read real input image of type <class 'itk.itkImagePython.itkImageF2'> and size itkSize2 ([1536, 128])
+  Padded input image to size itkSize2 ([1536, 128])
+  Performing FFT along axis 0
+  Generated complex frequency image of type <class 'itk.itkImagePython.itkImageCF2'> and size itkSize2 ([1536, 128])
+
+Code
+----
+
+Python
+......
+
+.. literalinclude:: Code.py
+   :language: python
+   :lines: 1, 16-
+
+
+Classes demonstrated
+--------------------
+
+.. breathelink:: itk::FFTPadImageFilter
+
+.. breathelink:: itk::Forward1DFFTImageFilter
+
+.. breathelink:: itk::CyclicShiftImageFilter
+
+.. breathelink:: itk::ComplexToModulusImageFilter
+
+.. breathelink:: itk::ComplexToPhaseImageFilter

src/Filtering/FFT/ComputeFFTInOneDimension/MouseLiver1DFFTModulusOutputBaseline.mha.sha512

@@ -0,0 +1 @@
+bcbead186f60040a16fa7091598b2da7ead8f97935efcd078c285ede14a57b717d53f95ffb2db1df6235cc19be67f98e617fc63deb24a18c7278345fd9ba24f7

src/Filtering/FFT/ComputeFFTInOneDimension/MouseLiver1DFFTPhaseOutputBaseline.mha.sha512

@@ -0,0 +1 @@
+f59ba4947c6394fa1b1dc77ff123b53d61b676a2bcdfd16758b0cd2672360cd3ed631e49890a8e0aa31a90eaa4fb44f1b10396b27896ffa26f0a144fc31bfd07

src/Filtering/FFT/ComputeFFTInOneDimension/MouseLiverModulusOutput.png.sha512

@@ -0,0 +1 @@
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src/Filtering/FFT/ComputeFFTInOneDimension/MouseLiverPhaseOutput.png.sha512

@@ -0,0 +1 @@
+20da0fff4cc937515571e60464f88b83f591f4e71af507d5206ab1460259df6cd0f1d6df98c55d880b25502b49586d5d789f918d4702b5c411d745a88fe7fec2

src/Filtering/FFT/ComputeFFTInOneDimension/MouseLiverRF.mha.sha512

@@ -0,0 +1 @@
+e0db3e0f2409e80d0c707507f29b78c9d493e7d603010bfbfe6c97df6e56b6c92c22c3ce7e7894cb27c7321992314045fd7ce7ac1d22c657e8ec0b4d37495b9e