PyQt/PySide: How do I convert QImage into OpenCV's MAT format

Question

I\'m looking to create a function for converting a QImage into OpenCV\'s (CV2) Mat format from within the PyQt.

How do I do this? My input images I\'ve been working

Answer 1

After much searching on here, I found a gem that got me a working solution. I derived much of my code from this answer to another question: https://stackoverflow.com/a/11399959/1988561

The key challenge I had was in how to correctly use the pointer. The big thing I think I was missing was the setsize function.

Here's my imports:

import cv2
import numpy as np

Here's my function:

def convertQImageToMat(incomingImage):
    '''  Converts a QImage into an opencv MAT format  '''

    incomingImage = incomingImage.convertToFormat(4)

    width = incomingImage.width()
    height = incomingImage.height()

    ptr = incomingImage.bits()
    ptr.setsize(incomingImage.byteCount())
    arr = np.array(ptr).reshape(height, width, 4)  #  Copies the data
    return arr

Answer 2

I tried the answer given above, but couldn't get the expected thing. I tried this crude method where i saved the image using the save() method of the QImage class and then used the image file to read it in cv2

Here is a sample code

def qimg2cv(q_img):
    q_img.save('temp.png', 'png')
    mat = cv2.imread('temp.png')
    return mat

You could delete the temporary image file generated once you are done with the file. This may not be the right method to do the work, but still does the required job.