shakeshuck
Member
Something I've been pondering recently; hoping someone in the know can fill in the blanks of my knowledge...
Is the noise level of a pixel constant (excluding temperature effects), or does it vary with exposure?
The reason I ask is that I've been wondering if some sort of pre-exposure (like we did in the old days of film
) would help reduce noise for low-level detail (and potentially increase dynamic range).
Hopefully I can explain what I mean - I'm not sure of units here so take values written merely as a method of explanation:
If a pixel has a 20 photons of noise when 'empty', and our exposure is 20 photons, our detail will get lost in the noise. If we were to add a light source in the camera at exposure time and add 40 photons of light to the cell (so our exposure is now 60 photons in total), do we still have 20 photons of noise, or is it reduced because we now have more 'real' signal to activate the cell? If so, we could potentially remove the extra light we added (in post) to give a better signal/noise ratio on our actual exposure.
I'm guessing the reality is that after removing 40 photons we'd still be left with 20/20 and there'd be no improvement?
Is the noise level of a pixel constant (excluding temperature effects), or does it vary with exposure?
The reason I ask is that I've been wondering if some sort of pre-exposure (like we did in the old days of film
) would help reduce noise for low-level detail (and potentially increase dynamic range).Hopefully I can explain what I mean - I'm not sure of units here so take values written merely as a method of explanation:
If a pixel has a 20 photons of noise when 'empty', and our exposure is 20 photons, our detail will get lost in the noise. If we were to add a light source in the camera at exposure time and add 40 photons of light to the cell (so our exposure is now 60 photons in total), do we still have 20 photons of noise, or is it reduced because we now have more 'real' signal to activate the cell? If so, we could potentially remove the extra light we added (in post) to give a better signal/noise ratio on our actual exposure.
I'm guessing the reality is that after removing 40 photons we'd still be left with 20/20 and there'd be no improvement?
