Print Head Alignment
A calibration routine that corrects for mechanical offsets in how the print head lays down ink in each direction.
In depth
A head that is fractionally misaligned produces a slightly soft or doubled appearance, most visible in fine detail and text, because droplets from the leftward and rightward passes do not land on the same spot. Alignment should be rerun after transporting the printer or changing paper thickness substantially.
Examples in practice
Realigning the head restores crispness to fine detail that had begun to look subtly doubled.