What dose Grain mean???

Question

Ok so i want to know what Grain means in a picture. Is it the detail or what?

Answer 1

Here you go: (grain=noise)

http://en.wikipedia.org/wiki/Image_noise

Answer 2

Grain can mean two different things:

For film cameras, grain is simply the size of the grains of silver halides that capture the image.  The light sensitive silver halide crystals (AgBr, AgI, etc.) are incredibly fine.  The higher the ISO, the larger the crystals are and the more light sensitive the film is.  When enlarged, grain becomes more noticable, leaving a sort of "gritty" look on the image.  Generally, tight grain is perfered as it renders detail the best. Sometimes I personally like to blow out the grain a little bit, just because I sometimes like that "gritty" feel to shots.

With digital cameras, it's still based on the ISO, but slightly different.  The sensors of digital cameras have individual pixels all crammed together.  When the ISO is increased, more power is coursing through each individual pixel.  This causes heat to build up, and can cause image noise, false information, to show up.  The larger the image sensor and the less compact the individual pixels are jammed in there, the better the camera is at dealing with higher ISOs.

It's oversimplifying to say that Digital "Grain" is the same as film grain.  While there are similarities, to say that they are one and the same is quite a stretch.