Slag control in small‐ and medium‐scale (SME) foundries is based on operator's experience, as foundry operators can hardly see a visual difference between liquid metal and liquid slag at metal‐making temperatures with the naked eye. With increasing requirements of high‐quality castings, it is imperative that foundry SMEs employ smart, innovative, affordable technologies to assist the operators in real‐time slag monitoring to stay competitive in the market. In this work, an Operator Vision Assistance System (OVIAS) is developed to enhance the operator's vision in differentiating liquid metal from liquid slag and to provide real‐time visualization and control of slag. A prototype of the OVIAS is set up and tested on imaging a metal bath surface in a 2.5 t induction furnace at Österby Gjuteri AB, Sweden. Tests confirm the potential of the OVIAS in real‐time slag visualization. OVIAS can assist the foundry operators in optimizing the amount of slag coagulant addition during melting stage and in de‐slagging operation. Industrial calibration of OVIAS is performed but must be further confirmed with lab‐scale tests. The OVIAS can serve as a cost‐efficient, flexible alternative to current expensive infrared‐based systems in providing real‐time improved visualization of slag in foundry SMEs as well as larger mills.