A flow meter includes a background pattern disposed behind a drip chamber, an image sensor, and a processor. The image sensor has a field of view and is configured to view the drip chamber within the field of view. The processor is coupled to the image sensor to receive image data therefrom and captures, using the image sensor, an image of the drip chamber and at least a portion of the background pattern, examines the image, and adjusts a flow rate of fluid flowing through a fluid line in accordance with the examination of the image.