Noise vs Grain?

Could you please explain (in not so technical terms) what noise is, and the

difference between it and grain? And how to avoid it. Merci beaucoup!

Grain is the (visible) crystal grain structure on film. The higher the speed (ISO/ASA) of the film used, the more grain dots are usually noticable (because of the larger crystals/dye clouds compared to a "slow" film) and result in a picture with with less resolution. Underexposing also leads to more visible grain.

 

Noise is signals recorded by a digital sensor (or post-processing, i.e., JPEG artifacts) that aren't really there. High temperature, high ISO setting and long shutter speeds can result in a colorful pattern across the final image that give a fuzzy and unlean look. Underexposing also augments visible color noise.

In effect, not so much difference, although as Bueh has said the cause is very different. In the examples below, the blowup on the left is a 100% crop from a slide taken with GAF (Ansco) 500 ISO film- very good for low light, but as you can see, very grainy in this picture of the Eiffel Tower in the dusk. On the right, is a 100% crop from a picture taken with an EF 50mm f/1.8 camera at ISO 3200 from a moving car, through the windshield.<div></div>

The GAF slide was scanned at 4000dpi, for what it's worth.

Grain is part of the film, grain gets larger with higher ISO films, because of the bigger chunks of silver halide,grain is also produced by different developement technigues of the film, if you are sloppy and the tempture is off or the time is too long you produce more film grain,, certain grain patterns look great, like tri-x..Noise is a electronic thing, if you are say in your car and the radio is playing and the station is far away, you have a weak signal and are hearing alot of hiss and noise instead of the music, this hiss/noise is because there is a weak signal..not enough signal, so where there is no signal there is noise,in audio you hear that, in stills/video you see that,it is visual noise.. light creates voltage when it hits the sensor and makes a signal to recreate a visual image, if the light is low it cant create as much signal, so the lack of signal is noise,the quality of the sensor and electronic of the camera and how the camera processes the signal all contributes to the noise level of a camera,I asked the SONY rep one day what the difference was between the $30,000 betacam and the $10,000 betacam and he said $20,000 worth of noise..so if you are in low light and they aint much signal being produced , you are gonna get a noise image,if you have cheap sensor and cheaper quality componets in your camera to process that signal, you are going to get more noise, if you bump up the ISO/gain, say 100 to 800 ISO..you are really amplifying the noise,along with the signal,but you gotta get the shot.... as the chips and electronic get better the noise goes down.So it is going to get better,,SONY just announced a new killer chip today so lookout Canon & Nikon.

This is an interessting issue often neglected compairing digital to film photography. Most people argue about the advantages of any system but I find it more interessting to see how a system is like when it comes to it's limits. I've heard of no one who loves pixel noise, but I know many photographers who love the grainy look of their b&w photos.

There are basically two kinds of digital camera noise: luminance and chroma (or chrominance).

 

Luminance noise tends to resemble film grain - gritty or, at higher ISOs, a bit chunky.

 

Chroma noise shows up as discolored blotches, typically reddish and greenish (tho' blue and yellow will show up too). This is what contributes to that sickly look on skin tones and odd look of lighter colored solid tone objects such as walls.

 

Both types can be fixed independently with most noise reduction software. So if you happen to like gritty grain but want to get rid of the splotchy colors, you can reduce the chroma noise and keep the luminance.

I'm a great fan of pixel noise, Stefan! Mind you,I like to control it as much as possible (but "controling" includes accentuating, as well as reducing, it.)

As an old GAF user, I find the comparison I did above very much in favor of the digital noise, too. You can recover from noise with software, but even without fixing, the effect is not always unpleasant.

Old Tri-x freek here....now gone digi,(okay not completely), I love noisy digitals.

I like to play with low pixel point&shoots.

 

So, Stefan....here's another one for ya.