Cohen’s d is mean/stdev.
This is an easy calculation in imcalc - select the mean and the stdev images, so
...
i1./(i2.*(i2>0) +999999.*(i2<=0))
Strickly Strictly speaking, it’s not 0, just 1/999,999.
Note: keep the dots (“.”) in those formulas. Otherwise, matlab tries to do matrix math.