Techniques are shown for generating image frames from a media presentation, selecting candidate thumbnails from the generated image frames using a selection process, and testing each selected candidate thumbnail for a success ranking relative to a target metric. The probability of choosing a selected candidate thumbnail with a success ranking higher than all other selected thumbnails as an optimum thumbnail for presentation to a user is based, at least in part, on the ratio of the success ranking of the selected candidate thumbnail with the highest success ranking to the sum of the success rankings of all of the selected candidate thumbnails. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.