Table 4. Formulas for color features.

Feature	Formula
Mean	x ¯ = 1 N ∑ 1 = 1 N x i
Standard Deviation (S.D.)	σ = 1 N − 1 ∑ i = 1 N ( x i − x ¯ ) 2
Skewness	γ 1 = 1 N − 1 ∑ 1 = 1 N ⌈ x i − μ σ ⌉ 3
Kurtosis	γ 2 = 1 N − 1 ∑ 1 = 1 N ⌈ x i − μ σ ⌉ 4 − 3