Merge pull request #26 from zivy/pyside

Utilities for converting to and from PySide QImage, QPixmap.

Author: zivy

.github/workflows/docs.yml

@@ -37,7 +37,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          python -m pip install -r docs/requirements.txt .[vtk,dask]
+          python -m pip install -r docs/requirements.txt .[vtk,dask,pyside]
       - name: Build Sphinx Documentation
         run: |
           make -C docs html

.github/workflows/main.yml

@@ -48,9 +48,12 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        python -m pip install -e .[vtk,dask] -r test/requirements.txt
+        python -m pip install -e .[vtk,dask,pyside] -r test/requirements.txt
+        sudo apt install libegl1
 
     - name: Test with pytest
+      env:
+        QT_QPA_PLATFORM: offscreen
       run: |
         python -m pytest
 

SimpleITK/utilities/pyside.py

@@ -0,0 +1,114 @@
+# ========================================================================
+#
+#  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 SimpleITK as sitk
+import numpy as np
+from PySide6.QtGui import QPixmap, QImage
+
+
+def sitk2qimage(image: sitk.Image) -> QImage:
+    """Convert a SimpleITK.Image to PySide QImage.
+
+    Works with 2D images, grayscale or three channel, where it is assumed that
+    the three channels represent values in the RGB color space. In SimpleITK there is no notion
+    of color space, so if the three channels are in the HSV colorspace the display
+    will look strange. If the SimpleITK pixel type represents a high dynamic range,
+    the intensities are linearly scaled to [0,255].
+
+    :param image: Image to convert.
+    :return: A QImage.
+    """
+    number_components_per_pixel = image.GetNumberOfComponentsPerPixel()
+    if number_components_per_pixel not in [1, 3]:
+        raise ValueError(
+            f"SimpleITK image has {number_components_per_pixel} channels, expected 1 or 3 channels"
+        )
+    if number_components_per_pixel == 3 and image.GetPixelID() != sitk.sitkVectorUInt8:
+        raise ValueError(
+            f"SimpleITK three channel image has pixel type ({image.GetPixelIDTypeAsString()}), expected vector 8-bit unsigned integer"
+        )
+
+    if number_components_per_pixel == 1 and image.GetPixelID() != sitk.sitkUInt8:
+        image = sitk.Cast(
+            sitk.RescaleIntensity(image, outputMinimum=0, outputMaximum=255),
+            sitk.sitkUInt8,
+        )
+    arr = sitk.GetArrayViewFromImage(image)
+    return QImage(
+        arr.data,
+        image.GetWidth(),
+        image.GetHeight(),
+        arr.strides[0],  # number of bytes per row
+        QImage.Format_Grayscale8
+        if number_components_per_pixel == 1
+        else QImage.Format_RGB888,
+    )
+
+
+def sitk2qpixmap(image: sitk.Image) -> QPixmap:
+    """Convert a SimpleITK.Image to PySide QPixmap.
+
+    Works with 2D images, grayscale or three channel, where it is assumed that
+    the three channels represent values in the RGB color space. In SimpleITK there is no notion
+    of color space, so if the three channels are in the HSV colorspace the display
+    will look strange. If the SimpleITK pixel type represents a high dynamic range,
+    the intensities are linearly scaled to [0,255].
+
+    :param image: Image to convert.
+    :return: A QPixmap.
+    """
+    return QPixmap.fromImage(sitk2qimage(image))
+
+
+def qimage2sitk(image: QImage) -> sitk.Image:
+    """Convert a QImage to SimpleITK.Image.
+
+    If the QImage contains a grayscale image will return a scalar
+    SimpleITK image. Otherwise, returns a three channel RGB image.
+
+    :param image: QImage to convert.
+    :return: A SimpleITK image, single channel or three channel RGB.
+    """
+    # Use constBits() to get the raw data without copying (bits() returns a deep copy).
+    # Then reshape the array to the image shape.
+    is_vector = True
+    # Convert image to Format_RGB888 because it keeps the byte order
+    # regardless of big/little endian (RGBA8888 doesn't).
+    image = image.convertToFormat(QImage.Format_RGB888)
+    arr = np.ndarray(
+        (image.height(), image.width(), 3),
+        buffer=image.constBits(),
+        strides=[image.bytesPerLine(), 3, 1],
+        dtype=np.uint8,
+    )
+    if image.isGrayscale():
+        arr = arr[:, :, 0]
+        is_vector = False
+    return sitk.GetImageFromArray(arr, isVector=is_vector)
+
+
+def qpixmap2sitk(pixmap: QPixmap) -> sitk.Image:
+    """Convert a QPixmap to SimpleITK.Image.
+
+    If the QPixmap contains a grayscale image will return a scalar
+    SimpleITK image. Otherwise, returns a four channel RGBA image.
+
+    :param qpixmap: QPixmap to convert.
+    :return: A SimpleITK image, single channel or four channel.
+    """
+    return qimage2sitk(pixmap.toImage())

pyproject.toml

@@ -22,6 +22,7 @@ dynamic = ["dependencies", "version"]
 [project.optional-dependencies]
 vtk=['vtk>=9.0']
 dask=['dask']
+pyside=['PySide6']
 
 [tool.setuptools]
 packages = ["SimpleITK.utilities"]
@@ -31,4 +32,4 @@ packages = ["SimpleITK.utilities"]
 dependencies = {file = ["requirements.txt"]}
 
 [tool.setuptools_scm]
-write_to = "SimpleITK/utilities/_version.py"
+write_to = "SimpleITK/utilities/_version.py"

test/test_pyside.py

@@ -0,0 +1,36 @@
+import SimpleITK as sitk
+from PySide6 import QtWidgets
+from SimpleITK.utilities.pyside import sitk2qpixmap, qpixmap2sitk
+
+
+def test_pyside():
+    # QPixmap cannot be created without a QGuiApplication
+    app = QtWidgets.QApplication()
+
+    # Test grayscale
+    scalar_image = sitk.Image([2, 3], sitk.sitkUInt8)
+    scalar_image[0, 0] = 1
+    scalar_image[0, 1] = 2
+    scalar_image[0, 2] = 3
+    scalar_image[1, 0] = 253
+    scalar_image[1, 1] = 254
+    scalar_image[1, 2] = 255
+
+    qpixmap = sitk2qpixmap(scalar_image)
+    sitk_image = qpixmap2sitk(qpixmap)
+    # Compare on pixel values, metadata information ignored.
+    assert sitk.Hash(sitk_image) == sitk.Hash(scalar_image)
+
+    # Test color
+    color_image = sitk.Image([2, 3], sitk.sitkVectorUInt8, 3)
+    color_image[0, 0] = [0, 1, 2]
+    color_image[0, 1] = [4, 8, 16]
+    color_image[0, 2] = [32, 64, 128]
+    color_image[1, 0] = [0, 10, 20]
+    color_image[1, 1] = [30, 40, 50]
+    color_image[1, 2] = [60, 70, 80]
+
+    qpixmap = sitk2qpixmap(color_image)
+    sitk_image = qpixmap2sitk(qpixmap)
+    # Compare on pixel values, metadata information ignored.
+    assert sitk.Hash(sitk_image) == sitk.Hash(color_image)