OAK1 Lack of lens performance?

SatoruNoguchi

I am testing this by shooting at 4K with an OAK1 fixed lens and cropping to 1080.

However, the cropped 1920x1080 image seems lower resolution than a pure 2 megapixel camera.

Could it be that the performance (accuracy) of the lens is not sufficient for a 12 megapixel CMOS?

jakaskerl

SatoruNoguchi
What do you mean lower resolution? The amount of pixels should be the same in both cases.

Thanks,
Jaka

SatoruNoguchi

jakaskerl

If a 12-megapixel CMOS with a 1-megapixel resolution lens is used, the data will be 12 megapixels in terms of data, but the actual resolution will be equivalent to 1 megapixel.

In other words, the actual resolution is inferior to that of a 2-megapixel CMOS with a 2-megapixel resolution lens.

jakaskerl

SatoruNoguchi
If 1MP resolution is selected, the pixels will be binned and there won't be 12MP in terms of data. The resolution will be worse than on the 2MP sensor with full resolution. If you want to preserve the quality, you can use ISP scaling which uses some nifty downscaling algorithm, so more information is preserved.

Thanks,
Jaka

SatoruNoguchi

jakaskerl

So the performance of the lens is low, so downscaling should be used to cover it up. Does this mean that the performance of the lens is low, so downscale it to fool us?

jakaskerl

SatoruNoguchi
Not sure what kind of quality you expect.
The 1080p should work fine. If you want better color accuracy, then ISP downscaling is the way to go, but it will introduce additional latency because of acquisition and processing time.

Thanks,
Jaka

SatoruNoguchi

What I am saying is that 1900 lines (18-20 zone =4K) are visible in the center of the ISO 12233 resolution chart,

jakaskerl

SatoruNoguchi
I see. The lens is probably not good enough for the max sampling rate of the sensor at full res (2160/2 =1080).
If you crop the image to 1080p, you halve the number of lines so you actually get about 950lp/ph - this is still probably above the MTF cut-off of the lens so you get a blurry image.

You should be fine if you downscale the image to 1080p though, because you are essentially applying a low pass filter and then resampling at lower nyquist limit - so the end result looks sharper. Same goes for your 2MP sensor which likely has a similar lens but can perceive more detail because of the lower frequencies.

Thanks,
Jaka