# Add both to the new stack
        newStack.addSlice(None, cp1)
        newStack.addSlice(None, cp2)

    # Create a new ImagePlus with the new stack newStack
    newImp = ImagePlus("my composite", newStack)
    newImp.setCalibration(imp1.getCalibration().copy())

    # Tell the ImagePlus to represent the slices in its stack
    # in hyperstack form, and open it as a CompositeImage:
    nChannels = 2  # two color channels
    nSlices = stack1.getSize()  # the number of slices of the original stack
    nFrames = 1  # only one time point
    newImp.setDimensions(nChannels, nSlices, nFrames)
    #comp = ImagePlus.CompositeImage(newImp, CompositeImage.COMPOSITE)
    comp = ImagePlus.CompositeImage(newImp)
    comp.show()

    imp1 = comp
else:
    print "Opening single channel:"
    print "\t" + filepath1
    imp1 = IJ.openImage(filepath1)
    imp1.show()

myCalibration = imp1.getCalibration()
myCalibration.setUnit("um")
myCalibration.pixelWidth = float(voxelx)
myCalibration.pixelHeight = float(voxely)
myCalibration.pixelDepth = float(voxelz)
imp1.setCalibration(myCalibration)