luminance brightness (monochrome) of an image (e.g., Y or YUV or YIQ
Transform color image CFVR from RGB color space to YIQ
and estimation YFVR component and IQFVRcomponents.
R G B X Y Z 256 levels - - - - - Otsu (full image) + + + + + Kapur (full image) + + + - - Otsu (N=20) - + - - + Kapur (N=20) + - - - - Otsu (N=50) + + + - + Kapur (N=50) - + - - - Otsu (N=100) + + + - + Kapur (N=100) - + - - - Otsu (N=200) + + + + + + Kapur (N=200) + + - - - Otsu (N=500) + + + + + Kapur (N=500) + + + - - Otsu (N=1000) + + + + + Kapur (N=1000) + + + - - LAB YIQ
YCbCr ASH 256 levels - - - Otsu (full image) + + + + Kapur (full image) - + + + Otsu (N=20) + - - Kapur (N=20) - - - + Otsu (N=50) + + + + Kapur (N=50) - - - + Otsu (N=100) + + + + Kapur (N=100) + + - Otsu (N=200) + + + + Kapur (N=200) + + + + Otsu (N=500) + + + + Kapur (N=500) + + + + Otsu (N=1000) + + + + Kapur (N=1000) - + + + TABLE II.
The size and shape of these ellipses vary in the color models used in image processing, including the HSI and YIQ
Assessment scores (MOS with confidence interval) for each video scene in all three tests: SS-1 (YPbPr), SS-2 (YCbCr) and SS-3 (YIQ
) are presented in Fig.
Hence the conventional color spaces such as YIQ
, YCbCr, L*a*b*, and HSV are more effective than original RGB color space at face recognition.
Nonetheless, most of the studies so far used the green (G) component of RGB color space for blood vessel recognition with some using luminance (Y) from YIQ
color space .
There are many color spaces, some are designed for computer graphics, such as YIQ
, HSV, HIS and GLHS (generalized LHS) (AO Linmi, et al., 2001).
Mali, "Comparative performance analysis of DWT-SVD based color image watermarking technique in YUV, RGB and YIQ
color spaces," International Journal of Computer Theory and Engineering, vol.
Therefore, majority of color spaces (YCbCr, HSV, YUV, HSL, YIQ
etc.) have been evolved or used for the identification of skin or non-skin pixels.
For example, in , Zhao and Xi introduced mean shift as a smooth filter for processing YIQ
color images and compared it with Wiener filter.