What is 'noise'?

[Bolly]

Hi all

What is noise? I have seen a few threads about reducing it and seen a few reviews about a camera preforming betting at higher ISO with less noise etc but what is noise? What am I looking for?

Any pics to explain?

Thanks

Bolly

 

[Suvv]

Explanation and pics here. There's lots more on that site as well

 

[Bolly]

Brilliant! I will have a good read of that later!

Bolly

 

[HoppyUK]

When you turn an audio amplifier up high, you can hear it hum and hiss in the quiet bits - it's the sound of the amp, not the music.

Image noise is exactly the same, produced by the camera's processing engine (basically an amplifier) and that's also why it's called noise.

 

[Major Eazy]

Hi all

What is noise? I have seen a few threads about reducing it and seen a few reviews about a camera preforming betting at higher ISO with less noise etc but what is noise? What am I looking for?

Any pics to explain?

Thanks

Bolly

In short: Noise is a digital version of film's grainy images at higher ISO speed.

 

[Bolly]

When you turn an audio amplifier up high, you can hear it hum and hiss in the quiet bits - it's the sound of the amp, not the music.

Image noise is exactly the same, produced by the camera's processing engine (basically an amplifier) and that's also why it's called noise.

Makes sense.

Will try and look for it now!

Bolly

 

[jon ryan]

Noise is what you get if you post a thread asking: "what's real street photography, then?"

 

[fracster]

When you turn an audio amplifier up high, you can hear it hum and hiss in the quiet bits - it's the sound of the amp, not the music.

Image noise is exactly the same, produced by the camera's processing engine (basically an amplifier) and that's also why it's called noise.

Very simple explanation of a complex, to beginners, question. Nice one Richard....

 

[st599]

Hi all

What is noise? I have seen a few threads about reducing it and seen a few reviews about a camera preforming betting at higher ISO with less noise etc but what is noise? What am I looking for?

Any pics to explain?

Thanks

Bolly

"Noise is a random fluctuation in an electrical signal, a characteristic of all electronic circuits." it's unwanted but always present.

Each Pixel on the sensor has noise associated with it (temperature causing random movements of electrons is the major noise source).

The amplifier then amplifies the wanted signal and unwanted noise and adds some more noise of it's own, the higher the gain (ISO) the more noise added.

When they say good performance at high ISO, they mean relative to other cameras. On a given camera, higher ISOs will create more noise.

Finally, it gets converted to digital, say your pixel value is 16.45567 but your camera can only represent 16 or 17 - this also looks like noise as it's a fluctuation from the real value.

 

[G.K.Jnr.]

When you turn an audio amplifier up high, you can hear it hum and hiss in the quiet bits - it's the sound of the amp, not the music.

Image noise is exactly the same, produced by the camera's processing engine (basically an amplifier) and that's also why it's called noise.

Hi, Never heard it described like that before but absolutely correct. Brilliant answer!!!

 

[Nod]

IIRC, it got the label "noise" since it's the visual equivalent of the hiss you get from an off tune radio, completely random.

Last week's (cover date 20 April 2013) was a special issue and tells you all you ever wanted to know about noise (and a whole lot more!), how to control it at capture and in PP.