When fixing exposure on underexposed digital photos i get lots of noise. What's thereason for that?

Question

When fixing exposure on underexposed digital photos i get lots of noise. What's thereason for that?

Answer 1

Essentially CCD sensors are extremely dense and susceptible to noise. Like any electrical device, the individual sensors on a CCD have a fixed level of noise. When you have a properly exposed photo, you have a high signal:noise ratio and the noise is relatively insignificant, but when your signal is weak (i.e. low light) your s:n ratio is low and noise becomes a factor. By fixing exposure digitally you're amplifying both signal and noise and therefore it becomes more obvious.



If you want low light capability, your only real choice is a DSLR, their larger sensors have better sensitivity. Also, Canon DSLR's tend to have CMOS sensors which are less noise prone as well (fewer electrical components).

Answer 2

Also check to see if your camera shoots in RAW format (versus .jpeg). If you shoot in RAW you will have greater ability to correct the exposure after the picture is taken in a photo editing tool like Photoshop or Apple's new Apperature. See included link for advantages of RAW over .jpeg.