A camera chip performs the digitalization in the RGB color space. This is the color space of light in which
the human eye breaks down the colors it sees into red, green and blue elements, before our brain puts them
back together again into a perceived color.
The picture viewed thru a monitor, which also displays colors using the RGB model, looks different because
this device cannot display as many shades of color as the camera chip can capture. And … if you send the photo
to the printer, the result will be slightly different! This is due to the fact, that the printer doesn’t expose
the paper so much as cover it in drops of four, six, eight or more ink colors.
For basic Web viewing and non-critical printing is not a problem. But, calibrating and profiling your monitor is the first,
and perhaps the most important step in setting up a digital workstation.
The monitor image is the only view you have of a digital file, and the quality of all image retouching depends
on how accurately the monitor displays it.
The cost to do this, ranges from free to very expensive.
If you want more technical informations on Gamma & Colors, I recommand you read these two excellent FAQ from Charles Poynton: