Introduction / Gamut
Understanding color gamut and colorspaces is an important part of getting the most out of development. Color gamut refers to the selection of colors that are in a given colorspace. There are three primary points in the development process where color gamut comes into play: raw conversion, editing, and printing.
Raw Conversion and Editing
Above is a chart with various color gamuts overlayed together. The visible spectrum represents all the colors which can be seen by the human eye. The typical RGB working colorspaces are represented by triangles. These RGB working colorspaces define the range of colors in your photograph when you are editing. Notice that in terms of the three RGB working colorspaces presented here, sRGB has the smallest gamut, followed by Adobe RGB 1998, and ProPhoto RGB being the largest. ProPhoto RGB is so large that in the blues and greens, it represents colors outside of what we can see.
FFDD uses the ProPhoto RGB gamut for editing and raw conversion. The reason for this can be seen from the chart. While Adobe RGB 1998 almost covers the range of colors of a typical digital camera, represented by the Canon 5D gamut in the chart, both sRGB and Adobe RGB 1998 fail to cover all the colors which can be reproduced by a high gamut paper, which in this example is being represented by the curvy Epson Luster 260 gamut (see the dark overlay in the chart).
Developing for Paper
The typical LCD display has a gamut very similar to sRGB. Note the gamut for the Epson Luster 260 paper is much larger, and gamut of the editing colorspace, ProPhoto RGB, is larger still. This represents a few challenges. All colors must be in the printing gamut, and some colors in this gamut cannot be reproduced by your screen.
Above is a selection of graphs. Each graph shows a 3D view of the colors which a printer can reproduce (represented by the Epson Luster 260 gamut), overlayed with a semi-transparent copy of a display gamut (represented by a LCD monitor). In this case the printer can reproduce much more saturated yellows, cyans, and midtone greens. While the display can reproduce a selection of bright reds, bright greens, blues, purples, and a huge amount of very dark shades which the printer cannot reproduce.