Every photographer and perhaps artists are aware of the Adobe RGB and Adobe sRGB profiles used in many modern digital cameras. Not so many of you may be aware of the Pro Photo Colour Space. The ProPhoto RGB colour space, also known as ROMM RGB (Reference Output Medium Metric), is an output referred RGB colour space developed by Kodak. It offers an especially large gamut designed for use with photographic output in mind. 

Unfortunately, when it comes to Giclee printing an image that has been saved with the Pro Photo Colour profile, you are going to run into some problems that may leave you disappointed with your results. Any image using the Pro Photo colour space will be printed within the printers defined colour gamut. Most modern 12 colour Photographic Printers will print to the nearest colour that it can print, effectively moving unreachable colours of the Pro Photo Colour space into a reachable and printable colour gamut. 

The following diagram shows the Pro Photo colour space together with the RGB and sRGB. Anything outside of the RGB colour space will be moved into the RGB colour space to be printed.

ProPhoto Colour Space when printing