If for each color channel, I were to use the HistogramTransformation tool, and manually set the Midtones value to the median value for that channel, is the result equivalent to performing Background Neutralization?
Not at all. The background neutralization algorithm is as follows:INR = IR - BIR + b
ING = IG - BIG + b
INB = IB - BIB + b
where INR, ING
are the color channels of the resulting (background-neutralized image); IR, IG
are the original color channels; BIR, BIG
are the mean backgrounds measured on the original channels, and b
is the target mean background
. Typically, b
is defined by:b = min( BRR, BRG, BRB )
where the BR
's are the mean backgrounds measured on the background reference image.
Each mean background is estimated as the median of the pixels in the background sampling range (defined by the lower and upper limit parameters in the BackgroundNeutralization tool) for the corresponding channel of the original or background reference image.