As a general rule, each user must provide the tool applied with particular values of its input parameters. An inexperienced user may hardly figure out their values and the tool developer must define the default values in order to help her/him. We present an approach to solve the problem with the help of multi-criteria optimization that is new in this formulation. We demonstrate our approach in closer details using an example from the automatic definition of optimal default parameters for real-time merging of visual objects. Our approach is generic and may be also used for any kind of such inverse problems.