There is described a method of filtering a captured image of a drip chamber configured to allow a drop of fluid to fall within the drip chamber, the method comprising: capturing an image of the drip chamber with an image sensor； determining if the captured image contains a visual obstruction； applying a blurring function to the captured image, the blurring function configured to eliminate an amount of detail in the captured image； and determining if the captured image contains a match to a template. There is also described an apparatus comprising: an image sensor configured to capture an image of a drip chamber； and a processor operatively coupled to the image sensor, the processor being configured to: determine if the captured image contains a visual obstruction； apply a blurring function to the captured image, the blurring function configured to eliminate an amount of detail in the captured image； and determine if the captured image contains a match to a template.
