ImageMagick does not make the error message "bg2.png is not a valid parameter". That error message comes from a Microsoft Windows program called convet.exe.
You can put your IM directory at the front of your system path, or always call convert with an explicit path, or rename it something like ...
ImageMagick version: ImageMagick-7.0.6-Q16) Operating System: Windows 7 (64 bits)
Hi, I am trying since two hours now to merge two image that contain transparency (and have the same size) together, here's what I tried so far (as individual commands):