ISP tuning

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
1

I have an ov7251 sensor. I’d like to tune the auto exposure algorithm. It appears the way to do this is through a camera_overrides.isp file.

Is it still the case that NVIDIA provides no support/documentation for tuning this file?

If not, is the best path just to use v4l2src and write my own AE algorithm?

3

Sorry to tell current we don’t public tuning to forum. But for the AE you can manually by argus API.

https://docs.nvidia.com/jetson/l4t-multimedia/group__LibargusAPI.html

4

@ShaneCCC all I see is the ability to set the exposure range, similar to nvarguscamerasrc.
If there is a way to explicitly set exposure through libargus I’d love to know the API function.

5

Maybe for a Y10 sensor and unless big forecast business with Jetson partners you might have to do your own one.
Before doing this from V4L2, for Argus you might try if this helps :
For setting manual exposure, just restrict the range to the same value as min and max.
Also note that other auto-adjustments may be in place for final image through Argus.
This might not be very clearly documented, AFAIK, but these may be involved:

  • gain. Try setting gainrange but monitor this from V4L API
  • ispdigitalgainrange
  • awblock and wbmode (manual, off)
  • aelock and exposuretimerange
  • maybe more depending on your L4T release or future ones

I won’t be able to tell more, I don’t have such sensor, but in case it helps… Sorry for any wasted time.

6

thanks @Honey_Patouceul

Assuming I go with the v4l2src route do you have experience calling the TEGRA CID controls from a user space application? Here is an example for the V4L2
V4L2_CID_EXPOSURE

Should I implement the V4L2 controls or can I just set TEGRA_CAMERA_CID_EXPOSURE

7

If you go with v4l2src that means you have to do debayer by yourself if it’s bayer sensors but didn’t for the YUV output sensors.