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 print head/substrate scan offsets, offsets between print heads, the use of different nozzle drive waveforms, and/or other techniques. Optionally, patterns of fill variation can be introduced so as to mitigate observable line effects in a finished display device. The disclosed techniques have many other possible applications.