The major impediment in controlling the interface between Bitumen-froth and Middlings in separation cells is the lack of safe and reliable sensors for interface level detection. This work describes a novel sensor for this problem using computer vision techniques on video frames captured from a sight glass camera. A simple edge detection method combined with state-space model based particle filtering is used to estimate the interface level and its quality. Industrial results show that the algorithm is robust to lighting changes and process abnormalities. Highly improved control performance results when the sensor estimates are used for feedback control. © 2009 Elsevier Ltd. All rights reserved.