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. Author manuscript; available in PMC: 2014 Mar 17.
Published in final edited form as: Skin Res Technol. 2012 Oct 1;19(1):e532–e536. doi: 10.1111/srt.12006

TABLE 1.

Color feature equations.

Color Features Equations
Absolute RGB Absolute R = Red Average over mask
Absolute G = Green Average over maskE*
Absolute B = Blue Average over maskE*, #
Relative RGB Relative R = Absolute R - Skin R
Relative G = Absolute G - Skin GE*
Relative B = Absolute G - Skin B
RGB Chromaticity R Chromaticity = R/(R+G+B)#
G Chromaticity = G/(R+G+B)
B Chromaticity = B/(R+G+B)
Relative RGB Chromaticity Relative R Chromaticity = Relative R/Relative(R+G+B)
Relative G Chromaticity = Relative G/Relative(R+G+B)#
Relative B Chromaticity = Relative B/Relative(R+G+B)
RGB Variance R Variance = Σ(R- total_R)2
G Variance = Σ(G- total_G)2
B Variance = Σ(B- total_B)2 E*, #
Relative Color Ratios Relative B/Relative R
Relative B/Relative G
Relative G/Relative R
Converting RGB Color Plane to XYZ Color Plane R to X = (R*0.49 + G*0.31 + B*0.20)/0.17697E*
G to Y = (R*0.17697 + G*0.81240 + B*0.01063)/0.17697
B to Z = (R*0.0 + G*0.01 + B*0.99)/0.17697#

Features in the final logistic regression model for BCC identification are marked by an emboldened “E*”, indicating their retention within the best-fit ellipse circumscribing the B-GO.

“#” indicates the final model of the expanded B-GO mask