JEFF CARLSON, MACWORLD:
"Here’s something I do more often than I’d like to admit, and I’ll bet plenty of other photographers do it, too.
"When shooting in a low-light environment, increasing the camera’s ISO (light sensitivity) setting allows you to capture brighter exposures without using a flash. Doing so introduces digital noise into the image, but often the tradeoff is worth it to get the shot. (Digital noise also occurs in low-light photos captured by smartphones, which offer you no control over the ISO.)
"The problem comes the next day when I forget to change the ISO back to a low value. I photograph something in the daylight, and end up with images that have plenty of exposure—plus a solid dusting of digital snow.
"Reducing that noise using software later isn’t as easy as applying a filter, but theNoiseless and Noiseless Pro applications for OS X from MacPhun come pretty close."
Read more, here.