1. A flow meter, comprising: a first image sensor having a first field of view, wherein the first image sensor is positioned to view a drip chamber within the first field of view; a background pattern positioned within the field of view of the first image sensor, wherein the background pattern includes first and second portions, the second portion of the background pattern is configured for detection of a free flow condition within the drip chamber; and at least one processor operatively coupled to the first image sensor, wherein the at least one processor is configured to: receive a first image from the first image sensor, and estimate at least one parameter of liquid within the drip chamber in accordance with a distortion of the background pattern caused by the liquid as indicated by the first image.