Costas Panagiotakis Anastasios D. Doulamis Georgios Tziritas Equivalent Key Frames Selection Based on Iso-Content Principles. 447-451 2009 19 IEEE Trans. Circuits Syst. Video Techn. 3 http://dx.doi.org/10.1109/TCSVT.2009.2013517 db/journals/tcsv/tcsv19.html#PanagiotakisDT09