z_project.py

import tifffile as tf
import numpy as np
from os.path import splitext

def z_project(fn):
    tiff = tf.TiffFile(fn)
    n = len(tiff.pages)
    immap = np.arange(n).reshape((-1, 2), order='F')
    d = {}
    d['cars'] = immap[:-1,0]
    d['srs'] = immap[:,1]
    for name, inds in d.iteritems():
        a = np.array([tiff[ind].asarray() for ind in inds])
        a.sort(axis=0) # intensity projection
        outname = '%s-%s.tif' % (splitext(fn)[0], name)
        tf.imsave(outname, a[-1,:,:])

One can simply use: np.amax(img, axis=0) (with img being the ndarray with slices first)