The use of advanced technologies in medicine allows to diagnose diseases in their initial stage. Its automatical parameterization is possible only in clear, qualified pictures. The paper investigates the initial processing of the picture of eye bottom which is necessary for the parameterization of sight nerve disc. This is the change of a colourful picture into a grey one and covering the picture with a net what allows to find a sight nerve disc. The paper describes the problems which disturb to precisely localize a sight nerve disc. This would be a net of blood-vessels, which is treated as noise in pictures. There is also a shortly discussed possible method for the further picture treatment – parameterization of a sight nerve disc. The research investigates and looks for optimal netting parameters that could more precisely and faster to find a sight nerve disc. A realised programme is presented which performs the initial picture treatment allowing to choose necessary netting parameters: the size of a cell, pace and form. In addition, the instruction of programme using is presented. The results received during the research are illustrated with the experiment description, diagrams and remarks.