Understanding Color and Color Spaces

Understanding color is the key to having the result that you want, and having your intended audience see what you want them to see.  Color theory can be complex.  Here are some major points.

 

Color is basically the brain's response to and interpretation of a small segment of the electromagnetic spectrum, called the visible light.  Thus, different people see colors differently (just as some people cannot hear certain sounds), and different machines (cameras, monitors, printers, etc.) respond to and "see" colors differently.

 

To standardize all the different "visibilities" of different machines and people, and to make sure that we all "see" the same thing, as intended by the presenter, the industry has developed different "color spaces":

 

CIE 1931 xy chromaticity diagram showing the chromaticities enclosed by
the ProPhoto RGB Color Space (blue outer triangle),
the Adobe RGB Color Space (yellow middle triangle),
and the sRGB Color Space (white inner triangle).
The vertices of the triangles represent the locations of the primary colors.
The cross in the center is the white point.
The areas of the triangle that are outside of the colored area
are colors that cannot be perceived by the human eye.
The color curve shows the color range from blue (380 nm) to red (700 nm).

 

* The L*a*b* Color Space:  This is a large set of the light spectrum that requires 48 bits to represent.  Needless to say, many of the colors in this space are beyond human perception.

 

* The ProPhoto RGB Color Space:  Developed by Kodak, this is a large set of the light spectrum that encompasses about 90% of the colors of the Lab Color Space, and corresponds to 100% of the "likely occurring" real-world colors (even though many are still beyond human perception).  It requires 16-bit per channel to work properly.

 

* The Adobe RGB Color Space:  Developed by Adobe in 1998, this is a set of the visible light spectrum that encompasses about 50% of the colors of the Lab Color Space, and corresponds to what the high-end color printers can reproduce.  It's used by color-aware applications (like Photoshop).

 

* The sRGB Color Space:  Developed by HP and Microsoft in 1996, this is a small set of the visible light spectrum that corresponds to what the CRT color monitors of the mid 1990s can display.  At the time, color monitor technology was poor, so this 8-bit-per-channel color space is small, and it's still in wide use today (because it's the "lowest common denominator"), especially by non-color-aware applications (like web browsers).

 

Why knowing all this is important?

 

* When you take photos, you want to take them in the ProPhoto RGB or Adobe RGB Color Space, if your camera allows you to.  Usually only the digital SLR cameras have that option.

 

* When you want to print your photos, and if you want the print to look the same as what you see on the monitor, you need to work in the Adobe RGB Color Space, work with a color-aware application, [ideally] calibrate your monitor in a dark room, [ideally] know what printer that you will print on, and [ideally] have that printer's profile installed on your machine.  Then tell the lab to "disable the color correction" when printing your photos.

 

* When you want to send your photos over email or to display them in the Internet, you want to export your photos to the sRGB Color Space, then email or display them over the Internet.