Color Space

Color space is the gamut (range) of color we are working with.  Our eyes can see a gamut of color in the visible light spectrum. This is referred to as "LAB" color, as depicted in the image to the right.

Red, Green, Blue - This color space represents the gamut of the transmissive light spectrum.  This area represents the color gamut monitors are able to reproduce.  Notice it is only a small fraction of what our brains can interpret.

Cyan, Magenta, Yellow, Key - This is the reflective color gamut, the color spectrum that offset printers and inkjets are able to reproduce.  Mixing cyan, magenta, and yellow produces a muddy black.  A fourth pigment, Key, is often black and used to counter this issue.

Notice in some areas, this spectrum is broader than the transmissive spectrum, yet in others it is narrower.

Adobe RGB (1998) - This is the color gamut introduced by Adobe.  It encompasses a larger part of LAB color and includes both sRGB and CMYK color gamuts.  This eliminates the loss of color information when moving between output devices.

To retain as much color information possible, it is best to work in aRGB color space.  However, there are a few issues with this.

Many digicams, notably ones that do not support RAW, record images in sRGB mode, so the color information is already lost.  It then becomes pointless to convert to aRGB, as it offers no benefit - we cannot create information from nothing.

Additionally, most web browsers and many print shops support only sRGB color.  Display an image with an aRGB color profile in a web browser window and it will clip the information it is not able to interpret.  As a result, images will appear washed out and contrast-less.  If the output device supports only sRGB, we will need to eventually convert from aRGB to sRGB.

However, use of aRGB gives us a broader range of color information to work with and fine tune.