OAK-D Pro W PoE OV9782 Purple colors outside

ddiirk

Hi,

We have ordered a bunch of Oak-D Pro W PoE's for testing. We notice when it's sunny outside, there is pink / purple coloring over the image. As I read from other posts, this can be the result of IR inference. We're using the OV9782 sensors.

Sunny examples:

Shaded example:

Is this only from the 940nm bandpass? Or can it be that the other IR light is not properly filtered?

If this is standard behavior for the Pro W PoE, is there another option which doesn't have this artifact?

Happy to hear your experiences!

jakaskerl

ddiirk
This is not from the bandpass since the color cameras should have an IR CUT filter. It is likely that some light still seeps through https://discuss.luxonis.com/blog/1302-ov9782-lens-color-filtering-enhancement

Thanks,
Jaka

ddiirk

Hi Jakaskerl,

Thank you for your response! If I understand correctly, the 940nm bandpass filter leaks through other light, causing this coloring?

We tried the Lens Shaded Correction proposed in the blogpost (using DepthAI v2.29), but the tuning blob does not work when both color & mono camera's are enabled and causes a crash.

Is there a fix available for this coloring when using the StereoDepth node?

jakaskerl

Hi ddiirk
This pink/purple tint in sunlight is expected with OV9782 + wide-FOV lenses. The IR-cut filter works best for light hitting it straight on, but at the edges of the image sunlight comes in at a steep angle and some IR still gets through. That IR content shifts colors towards pink, especially outdoors.

It’s not caused by the 940 nm bandpass filter (that’s only for the projector). Lens shading correction can reduce it a bit, but it won’t completely remove it. To avoid it entirely, you’d need a different sensor/lens combo with lower CRA or a different IR-cut filter design — for example, IMX378 doesn’t show this issue, though it’s rolling shutter rather than global.

Thanks,
Jaka