Optical indicators are based on active compounds, which undergo a definite colour chance depending on changes in exposure conditions. Indicators are used to monitor, for example, food product quality in real time and this way remaining shelf-life can also be better estimated. VTT has developed and patented special ultra-low-cost ink jet printable indicator systems for example in checking the freshness of food supplies. VTT has also developed indicator monitoring systems based on emerging camera phone technology. In this paper, the technologies and the operational environment, in which the new camera phone based quantitative indicator applications are developed, are described.