Change exposure with OpenCv - Linux

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1

Hi,

I’m using OpenCv to change exposure on my camera.
It works fine on Windows, but doesn’t work on linux.

I’m using cv::VideoCapture::set(cv::CAP_PROP_EXPOSURE, value).

Can you please help me with implement that on Linux?

Thanks!

2

There is a chance that the camera driver in linux does not expose that in it’s api. Maybe you can try auto exposure?

3

Hi,

It doesn’t work with auto exposure. I did the following:

cv::VideoCapture::set(cv::CAP_PROP_AUTO_EXPOSURE, 70)

Does it make sense?

Thanks!

4

auto exposure is a boolean, i.e. 0 or 1.

see:

can you affect your camera’s settings, on linux, using any other program, like VLC or guvcview?

5

Hi,

I’m using Open CV to change exposure, using cv::set(cv::CAP_PROP_EXPOSURE, value).
It works Great.

However - I would like to change the state back to auto exposure.
After using cv::set(cv::CAP_PROP_AUTO_EXPOSURE, 1), I’m expecting to see the frame with normal exposure, but it doesn’t happen. The frame stays with the same value. Is it possible?

Thanks!

6

did you read (and look at) multiple frames after changing the settings?

7

Using CAP_PROC_EXPOSURE, I can change exposure value successfully.

However, when trying to set auto exposure to on, using CAP_CROP_AUTO_EXPOSURE, it doesn’t work (setting auto exposure to off - works).

Do you know if the is a way to change auto exposure back to on?

Thanks!

8

do not use multiple accounts, do not open multiple threads for the same issue. I’ve merged the threads.

9

On windows use cap = cv2.VideoCapture(1, cv2.CAP_DSHOW) and
cap.set(cv2.CAP_PROP_SETTINGS, 1) opens camera settings. There you can check what the values typically are because 70 might be out of range.

10

Yes - I can see the values and change to auto exposure from the settings window. Can I do that from the code?

Thanks!