I found that images taken from IMX477 at Jetson nano have a lot background noise.
At the very dark environment (almost no lights exist), the images are supposed to have (0,0,0) RGB values.
However, it actually has normally (86,67,86) RGB pixel intensities like below.
It seems that IMX477 waste (0,0,0)~(86,67,86) range of pixel intensity.
Even considering the various noises, this seems like an excessive waste.
Yes, As you noticed, I set the gain range as maximum (16, 16) and ISP digital gain as (1, 1).
However, when I set the gain range to (1, 1), I could get only (86,67,86) pixel intensities in the low light condition but no white noise
That’s why I thought the problem was a background or dark noise.