An ink printing process employs per-nozzle droplet volume measurement and processing software that plans droplet combinations to reach specific aggregate ink fills per target region, guaranteeing compliance with minimum and maximum ink fills set by specification. In various embodiments, different droplet combinations are produced through different printhead/substrate scan offsets, offsets between printheads, the use of different nozzle drive waveforms, and/or other techniques. These combinations can be based on repeated, rapid droplet measurements that develop understandings for each nozzle of means and spreads for expected droplet volume, velocity and trajectory, with combinations of droplets being planned based on these statistical parameters. Optionally, random fill variation can be introduced so as to mitigate Mura effects in a finished display device. The disclosed techniques have many possible applications.