Camera grain problem

Other OS Support
1

Hi,

I ported OV7251 to Rubik Pi 3. The sensor is detected and streaming works, so basic bring-up seems OK.

My main issue is image quality, especially grain/noise behavior.

What I observe is:

  • when gain is 1, the image is dark but grain is relatively low
  • as soon as gain is increased to 2, grain increases a lot
  • so the main problem is not just that the image is dark, but that noise rises very aggressively with gain
  • streaming itself works, but image quality becomes poor once gain is raised

This makes me think the remaining issue is related to sensor gain behavior and/or tuning, rather than basic sensor bring-up.

I would like to understand:

  1. Is it normal for OV7251 to become this grainy already at gain 2?
  2. Is this more likely a tuning/chromatix issue, or sensor-side configuration issue?
  3. Is there any known good tuning approach for OV7251 on this platform?

Thanks.

tune_right_gain2
tune_right_gain2640×480 129 KB

tune_right_gain1
tune_right_gain1640×480 77.6 KB

2

I think you’re talking about MIPI camera, not USB camera.
If so, you’d better have access to QC private doc.
It’s mentioned here (this doc is public):

Qualcomm provides an interface for camera sensor driver developers and IQ tuning engineers to develop their own sensor drivers and perform custom IQ tuning. See Camera Sensor Driver Development and Tuning in the Camera Addendum document.

Since it’s not public info, we cannot discuss here in public.