Convert Python Opencv Image (numpy array) to PyQt QPixmap image

Convert Python Opencv Image (numpy array) to PyQt QPixmap image

To convert a Python OpenCV image (represented as a NumPy array) to a PyQt QPixmap image, you'll need to perform a series of steps to ensure the image data is properly converted and displayed in your PyQt application. Here's a detailed guide on how to achieve this:

Steps to Convert OpenCV Image to PyQt QPixmap

  1. Import Required Libraries:

    import cv2 from PyQt5.QtGui import QPixmap, QImage

  2. Read the Image Using OpenCV:

    Assuming you have an image file that you've read into OpenCV (represented as a NumPy array), or if you already have an image loaded in an OpenCV Mat object, you can convert it to a NumPy array.

    # Example: Reading an image using OpenCV image_cv = cv2.imread('example.jpg')

    Ensure image_cv is a NumPy array representing your image.

  3. Convert OpenCV Image to QImage:

    Use QImage to convert the OpenCV image (NumPy array) to a QImage. This step is crucial as PyQt handles images using QImage.

    height, width, channel = image_cv.shape bytes_per_line = 3 * width q_image = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped()
    • image_cv.data: Directly access the underlying image data in the NumPy array.
    • width, height: Dimensions of the image.
    • bytes_per_line: Number of bytes in each image row (3 * width for RGB images).
    • QImage.Format_RGB888: Specifies the image format (Format_RGB888 assumes 8-bit RGB channels).

    rgbSwapped() is used to swap the Red and Blue channels because OpenCV uses BGR order and QImage uses RGB order.

  4. Convert QImage to QPixmap:

    Finally, convert the QImage to a QPixmap for display in your PyQt application.

    pixmap = QPixmap.fromImage(q_image)

    Now, pixmap contains your image data in a format suitable for displaying in a PyQt application.

Example Application

Here's a complete example of how you might use this conversion in a PyQt application:

import sys import cv2 from PyQt5.QtWidgets import QApplication, QLabel, QVBoxLayout, QWidget from PyQt5.QtGui import QPixmap, QImage class ImageViewer(QWidget): def __init__(self): super().__init__() self.initUI() def initUI(self): layout = QVBoxLayout(self) self.label = QLabel(self) layout.addWidget(self.label) self.setLayout(layout) # Read image using OpenCV image_cv = cv2.imread('example.jpg') # Convert OpenCV image to QImage height, width, channel = image_cv.shape bytes_per_line = 3 * width q_image = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap pixmap = QPixmap.fromImage(q_image) # Display QPixmap in QLabel self.label.setPixmap(pixmap) self.setWindowTitle('Image Viewer') if __name__ == '__main__': app = QApplication(sys.argv) viewer = ImageViewer() viewer.show() sys.exit(app.exec_())

Explanation:

  • ImageViewer Class: Defines a simple PyQt QWidget (ImageViewer) with a QVBoxLayout containing a QLabel (self.label) where the image will be displayed.

  • initUI Method: Sets up the user interface, reads an image using OpenCV (cv2.imread('example.jpg')), converts it to a QImage (q_image), and then to a QPixmap (pixmap). Finally, it sets the QPixmap to the QLabel (self.label) for display.

  • Main Application: Sets up the QApplication and runs the PyQt event loop.

Notes:

  • Ensure you have PyQt5 installed (pip install PyQt5).
  • Replace 'example.jpg' with the path to your actual image file.
  • This example assumes your image is in RGB format. Adjust accordingly if your image has a different color format (e.g., grayscale or RGBA).
  • Handle errors and exceptions appropriately, especially when loading or converting images.

By following these steps, you can effectively convert and display images from OpenCV in a PyQt application using QPixmap. Adjust the example code to fit your specific requirements and image handling needs.

Examples

  1. Python OpenCV image to PyQt QPixmap

    • Description: Convert an image loaded with OpenCV (as a numpy array) to a QPixmap for display in a PyQt application.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV image (BGR) to QImage (RGB) image_qt = QImage(image_cv.data, image_cv.shape[1], image_cv.shape[0], image_cv.strides[0], QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap pixmap = QPixmap.fromImage(image_qt)

  2. Python OpenCV image to PyQt QPixmap example

    • Description: Example of converting an image from OpenCV to QPixmap in PyQt with step-by-step instructions.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV image (BGR) to QImage (RGB) image_qt = QImage(image_cv.data, image_cv.shape[1], image_cv.shape[0], image_cv.strides[0], QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap pixmap = QPixmap.fromImage(image_qt) # Display QPixmap in a QLabel or paint on a QPainter

  3. Python OpenCV Mat to PyQt QPixmap

    • Description: Convert an OpenCV Mat object (numpy array) to a QPixmap for PyQt GUI applications.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV Mat (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

  4. Python OpenCV numpy array to PyQt QPixmap

    • Description: Convert a numpy array (image data) from OpenCV to a QPixmap for PyQt GUI display.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV numpy array (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

  5. Python OpenCV Mat to QPixmap PyQt5

    • Description: Convert an OpenCV Mat (numpy array) to a QPixmap for PyQt5 applications.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV Mat (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

  6. Python OpenCV image to QPixmap PyQt

    • Description: Convert an image from OpenCV to a QPixmap for PyQt application display.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV image (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

  7. Python OpenCV image numpy to QPixmap PyQt

    • Description: Convert a numpy array (image data) from OpenCV to a QPixmap for PyQt application GUI.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV numpy array (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

  8. Python OpenCV numpy array to QPixmap PyQt5

    • Description: Convert a numpy array (image data) from OpenCV to a QPixmap for PyQt5 GUI application.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV numpy array (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

  9. Python OpenCV image numpy array to QPixmap

    • Description: Convert an image represented as a numpy array from OpenCV to a QPixmap for PyQt GUI display.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV numpy array (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

  10. Python OpenCV Mat to PyQt QPixmap example

    • Description: Example of converting an OpenCV Mat (numpy array) to a QPixmap for PyQt application display.
    • Code:
      import cv2 from PyQt5.QtGui import QPixmap, QImage from PyQt5.QtCore import Qt # Load image with OpenCV image_cv = cv2.imread('image.jpg') # Convert OpenCV Mat (BGR) to QImage (RGB) height, width, channel = image_cv.shape bytes_per_line = channel * width qimage = QImage(image_cv.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped() # Convert QImage to QPixmap qpixmap = QPixmap.fromImage(qimage)

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