AE exposure time limit, OV9282/OV9782 image quality and FPS improvements

[alex-luxonis]

Added CameraControl API:

• setAutoExposureLimit(uint32_t maxExposureTimeUs);
• setAutoExposureLimit(std::chrono::microseconds maxExposureTime);

Set a command to specify the maximum exposure time limit for auto-exposure. By default
the AE algorithm prioritizes increasing exposure over ISO, up to around frame-time
(subject to further limits imposed by anti-banding)

Can be applied both using initialControl, and at runtime.

Other FW changes: improved OV9282 and OV9782 image quality under low-light scenarios - high ISO (over 1300).
It got degraded (more noise) for the 800p/720p resolutions after the switch to the max-120fps configs: #620, was introduced with depthai v2.20.0 (and v2.21.0 for socket CAM_A).

Also improved maximum FPS, with new ranges per resolution of:

• THE_800_P: 1.687 .. 129.6 fps
• THE_720_P: 1.687 .. 143.1 fps
• THE_400_P: 1.687 .. 255.7 fps
  (For the latter to be achievable, will need to be paired with .setIsp3aFps(some_lower_rate) for which some further stability fixes are needed)

Related: luxonis/depthai-shared#153

[patripfr]

Hi,
On my OAK-1 MAX I am limiting the maximum autoexposure time using setAutoExposureLimit(limit)

However, every now and then (especially after large view point changes) the camera seems to ignore this and uses a longer exposure time. After a few seconds it jumps back to the commanded limit.
The observed behaviour can be seen in the following video:

The darker images are using the correct, low exposure time and you can see a bright flickering from time to time where the camera switches to a longer exposure time.

Any ideas how to address this issue?

[alex-luxonis]

Hi @patripfr , yeah we found this bug after the feature was introduced, it should have been fixed in v2.25.0 release. The auto-focus algo caused this problem when it ran again at a scene change, or periodically.
Could you try the latest release at the moment v2.25.1, or develop.

[patripfr]

that fixed it, thanks!