i just noticed something that I didn't expect :
the order of arguments matters in enblend3,
i.e. if you type :
enblend image1.tif image2.tif -o image1-2.tif
enblend image2.tif image1.tif -o image2-1.tif
you won't necessarily get the same results.
i put an example on my website, so that you can try by yourself.
this one works with enblend-3.0 but you can find examples for enblend-2.5 too.
does someone know where it can come from ?
Enblend creates a different mask for these two scenarios. The first explanation I can think of is that it splits ties in favor of the first image given on the command line while calculating the mask. I can't think of a particular part of the algorithm responsible for this right now though.