PyQt5 QImage from Numpy Array

Question

Considering the following code

from PyQt5.QtWidgets import QMainWindow, QLabel, QSizePolicy, QApplication 
from PyQt5.QtGui import QPixmap, QImage                                
from PyQt5.QtCore import Qt                                                                                              
import numpy as np                                                     
import sys



class Test(QMainWindow):                                                                                                                                                                                       

 def __init__(self):                                                                                                                                                                                        
     super().__init__()                                                                                                                                                                                     
     self.initUI()                                                                                                                                                                                          

 def initUI(self):                                                                                                                                                                                          
     self.setGeometry(10,10,640, 400)                                                                                                                                                                       

     pixmap_label = QLabel()                                                                                                                                                                                
     pixmap_label.setSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored)                                                                                                                                   
     pixmap_label.resize(640,400)                                                                                                                                                                           
     pixmap_label.setAlignment(Qt.AlignCenter)                                                                                                                                                              

     im_np = np.ones((1800,2880,3),dtype=uint8)                                                                                                                                                                                  
     im_np = np.transpose(im_np, (1,0,2))                                                                                                                                                                              
     qimage = QImage(im_np, im_np.shape[1], im_np.shape[0],                                                                                                                                                 
                     QImage.Format_RGB888)                                                                                                                                                                 
     pixmap = QPixmap(qimage)                                                                                                                                                                               
     pixmap = pixmap.scaled(640,400, Qt.KeepAspectRatio)                                                                                                                                                    
     pixmap_label.setPixmap(pixmap)                                                                                                                                                                         

     self.setCentralWidget(pixmap_label)                                                                                                                                                                    
     self.show()                                                                                                                                                                                            



def main():                                                                                                                                                                                                    
  app = QApplication(sys.argv)                                                                                                                                                                               
  win = Test()                                                                                                                                                                                               
  sys.exit(app.exec_())                                                                                                                                                                                      



if __name__=="__main__":                                                                                                                                                                                       
  main()  

I get the following error

TypeError: arguments did not match any overloaded call: QImage(): too many arguments QImage(QSize, QImage.Format): argument 1 has unexpected type 'numpy.ndarray' QImage(int, int, QImage.Format): argument 1 has unexpected type 'numpy.ndarray' QImage(bytes, int, int, QImage.Format): argument 1 has unexpected type 'numpy.ndarray'
QImage(sip.voidptr, int, int, QImage.Format): argument 1 has unexpected type 'numpy.ndarray' QImage(bytes, int, int, int, QImage.Format): argument 1 has unexpected type 'numpy.ndarray'
QImage(sip.voidptr, int, int, int, QImage.Format): argument 1 has unexpected type 'numpy.ndarray' QImage(List[str]): argument 1 has unexpected type 'numpy.ndarray' QImage(str, format: str = None): argument 1 has unexpected type 'numpy.ndarray' QImage(QImage): argument 1 has unexpected type 'numpy.ndarray' QImage(Any): too many arguments

According to this post this can be caused by numpy creating a view. Modifying the lines

 im_np = np.array(img)                                                                                                                                                                                  
 im_np = np.transpose(im_np, (1,0,2))                                                                                                                                                                              

To

im_np = np.array(img)                                                                                                                                                                                  
im_np = np.transpose(im_np, (1,0,2))                                                                                                                                                                              
im_np_cpy = np.copy(im_np)     

Produces the same error. To test that I am not passing a view I print the result of the test

im_np_cpy.base is im_np

and it's False. The image is visualised correctly with cv2. I am clearly missing something, any idea what?

Cheers!

Answer 1

I added a copy after the transpose like this:

im_np = np.transpose(im_np,(1,0,2)).copy()

and that worked for me.

Answer 2

Check if the module qimage2ndarray suits your needs, with just one line of code https://pypi.org/project/qimage2ndarray/

yourQImage=qimage2ndarray.array2qimage(yournumpyarray)

Answer 3

Ivan's answer is short and elegant, however while numpy uses (H, W) order, Qt uses (W, H) order. Therefore, to make it work, I have to exchange w and h in the second line:

h, w, _ = img.shape
qimage = QImage(img.data, w, h, 3 * w, QImage.Format_RGB888)

(I would have preferred to comment on the above answer but I don't have enough reputation.)