As far as I understand it additive noise has not to be uniform. I guess uniform refers only to the noise distribution it could also be a gaussian distribution.
I know about three different types of noise:
- Impulse Noise (salt and pepper noise)
- Additive Noise (gaussian, poisson, uniform)
- Multiplicative Noise (mostly observed in radar, ultrasound images)
The only noise which should not change from frame to frame is the impulse noise, because this noise is based on some dead pixels (salt and pepper) or other hardware defects.
Additive noise is the “standard” noise for light images which is normally assumed to be gaussian distributed, but poisson distribution would be more accurate but harder to model and uniform noise is simpler to model.
Multiplicative noise is based on the pixel value, this means that pixels with a low value only show small amounts of noise and pixels with high values show bigger amounts of noise.
I thought about the subtraction of the maxprojection not as a method to remove noise but more as a method to remove the background and everything else that is not moving.
I don’t think that it is possible to get rid of noise just by subtraction. For Additive noise I would use a gaussian filter, for impulse noise I would use a median filter and for multiplicative noise I actually don’t know what is best to use.