Understanding Web Colors
Photoshop CS3 Tutorial
How Web Colors Work in Photoshop
Web colors are defined using a six character hexadecimal format. You may be familiar with the standard RGB model of 256 values for each of the red green and blue values.
Open a blank document in Photoshop (File > New).
Click the Foreground Color swatch to open the color picker.
Click in the picker and select a bright red color. In this case, we selected an RGB value of 255, 0, 0.
Notice the box at the bottom of the picker with the # sign. This is the web hex equivalent. It reads #ff0000.
The first two characters are the red value, the second two are green and characters five and six define the blue. Each of the two characters goes from 00 to ff.
Pick a bright blue color with an RGB value of 0,0,255.
The web equivalent is #0000ff.