`plt.imread` is returning readonly images that can't be drawn on when rendering video

[Dominic-DallOsto]

I am getting the following error on this line when it tries to draw lines on the image when rendering the 2d video.

cv2.error: OpenCV(4.10.0) :-1: error: (-5:Bad argument) in function 'line'
> Overload resolution failed:
>  - img marked as output argument, but provided NumPy array marked as readonly
>  - Expected Ptr<cv::UMat> for argument 'img'

This answer on stackoverflow told me it was because the image was readonly. The image is loaded by the line img = plt.imread(self.image_path.format(img_id=img_id)) which seems to load the image as readonly. This doesn't happen when using cv2.imread

>>> plt.imread(self.image_path.format(img_id=img_id)).flags
  C_CONTIGUOUS : True
  F_CONTIGUOUS : False
  OWNDATA : False
  WRITEABLE : False
  ALIGNED : True
  WRITEBACKIFCOPY : False

>>> cv2.imread(self.image_path.format(img_id=img_id)).flags
  C_CONTIGUOUS : True
  F_CONTIGUOUS : False
  OWNDATA : True
  WRITEABLE : True
  ALIGNED : True
  WRITEBACKIFCOPY : False

Tested with:

• python 3.11.6
• opencv-python-headless 4.10.0.84
• matplotlib 3.9.1

[jasper-tms]

I had run into this too and made the same change locally, so agreed that the change from plt.imread to cv2.imread is fine and good.