Understanding mesopic vision is one of the hottest topics in lighting engineering [1]. The high importance of the field comes from the wide variety of the applications such as driving and other outdoor activities are performed in mesopic conditions at night. Therefore, it is extremely important to calculate the visibility of different objects in such conditions. In this paper, we present the algorithm and the first results of software, which is able to simulate the behaviour of human retina in scotopic, mesopic and photopic ranges, calculates the direction-dependent acuity. Our aim was to produce a practical tool to examine real-time situations. Therefore, classical camera recordings are used as input, which limits the accuracy but extends the range of applications.