I'm just beginning to try to understand PixelMath expressions, so please forgive my ignorance.

Pertaining to this expression:

G: iif(min($T[0],$T[2])>$T[1],min($T[0],$T[2]),$T[1])

I understand this to be saying:

1. Assuming for an SHO combination, $T[0] = SII, $T[1] = Ha and $T[2] = OIII

2. The first argument is comparing the lower of the minimum pixel sample values of SII and OIII to Ha's minimum pixel sample value. The result is either a 1 or a 0.

3. The inline IF statement is saying If the first argument is 1, then G is set to either SII or OIII, which ever has a smaller minimum pixel sample value.

4. However, it the first argument is 0, then G is set to Ha.

If this is correct, there seems to be a possibility that my PixelMath combination will completely ignore my Ha image.

Or am I reading this all wrong?

Incidently, I used this PixelMath expression in my last effort and was highly pleased with the elimination of my purple stars. So I must be mis-interpreting how the expression is evaluated. Help!