(R,G)  (M,A) Transformation Observed data {(R,G)} R = red channel signal G = green channel signal (background corrected or not) Transformed data {(M,A)} M = log 2 (R/G) (ratio), A = log 2 (R·G) 1/2 = 1/2·log 2 (R·G) (intensity)  R=(2 2A+M ) 1/2, G=(2 2A-M ) 1/2
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