//load ImageJ
%classpath config resolver scijava.public https://maven.scijava.org/content/groups/public
%classpath add mvn net.imagej imagej 2.0.0-rc-67

//create ImageJ object
ij = new net.imagej.ImageJ()

ij.op().help('project')

input = ij.scifio().datasetIO().open("http://imagej.net/images/clown.jpg")

ij.notebook().display(input)

import net.imglib2.FinalInterval

//create the output using only the first two dimensions of the input
interval = new FinalInterval(input.dimension(0), input.dimension(1))
imgType = input.firstElement()
projected = ij.op().create().img(interval, imgType)

//create the stats Op instance using op()
statsOp = ij.op().op("stats.mean", input)

//do the projection in the second dimension
projectDim = 2

ij.op().run("project", projected, input, statsOp, projectDim)

ij.notebook().display(projected)