How to set V4L2 exposure to manual mode in OpenCV & Python

Using OpenCV on Linux, if you have a video device that interfaces a V4L2 device such as a USB webcam:

camera = cv2.VideoCapture(0)

you can typically set the automatic exposure mode by setting exposure_auto to 1 (the following output is from v4l2-ctl -d /dev/video0 --all):

exposure_auto 0x009a0901 (menu)   : min=0 max=3 default=3 value=1
              1: Manual Mode
              3: Aperture Priority Mode

As you can see in our previous blogpost, exposure_auto (which is named V4L2_CID_EXPOSURE_AUTO in V4L2 in C/C++) is mapped to CAP_PROP_AUTO_EXPOSURE.

Therefore, you can enable manual exposure using

camera.set(cv2.CAP_PROP_AUTO_EXPOSURE, 1) # Set exposure to manual mode

You should, however, verify these settings using v4l2-ctl --all using your specific camera.