II. COLOR SPACES AND SKIN COLOR MODELS
A. Color Spaces
When a set of colors are represented using mathematical
expression it is called color space. In the literature many
different color spaces are employed like RGB, HSV, HSI,
YCbCr, CIE-Lab, CIE-Luv. The initial step is to select the
color space which helps in efficient discrimination of skin and
non-skin pixels. Opting YCbCr color space helps to a greater
extent in this regard [2]. Fig 2 shows the color space available.
RGB is termed as basic color space whereas YCbCr is termed
as orthogonal color space and HSI is termed as perceptual
color space. RGB is also known as primary source of light
color as all other color spaces are derived using RGB color
space model.[3]