The Gen 2 image intensifier is keeping a parallel technology development status with the Gen 3 image intensifier and the debate over the generation division and performance upgrade is also accompanying their development. Over time, as substantial breakthroughs for multi-alkali photocathode in the extended spectral range occur, as well as the development of filmless micro- channel plates(MCP) in some GaAs photocathodes image intensifiers, the term “Generation” for image intensifiers has arguably lost meaning. However, there is still lack of accurate comparison assessments for the filed performance that both generations have achieved. Though the existing military specification cannot fully reflect the upgraded image intensifier characteristic and its actual field performance, standards updates as well as investigations of the link between these characteristic parameters and the actual field performance are necessary.