The invention relates to an optimization method for improving the reliability of a collection and discharge of articles in a picking process using a robot. An article is collected from or out of a first article carrier and is placed down or thrown into or onto a second article carrier by means of a gripping unit on the robot head. In an image processing step, a gripping position for the gripping unit is calculated for collecting the article(s) by determining at least one dimension based on a captured image and by a range allocation being determined by means of a comparison with dimension ranges. Depending on a confidence value, a dimension value is determined, from stored article reference data or from a normalization value of the dimension range and allocated to the determined dimension. In a preparation step, a mathematical scattering measure function is applied for the determined dimension and for the dimension ranges, and normalization values and confidence values of the dimension ranges are determined therefrom.