i, j = numpy.nonzero(fpInput == True)
for indexI in i:
    for indexJ in j:
        fpOutput[indexI - 1, indexJ] = True
fpOutput[indexI, indexJ - 1] = True
fpOutput[indexI + 1, indexJ] = True
fpOutput[indexI, indexJ + 1] = True
numpy.memmap from numpy operations