The　constrained　Viterbi　algorithm　(C-VA)　makes　use　of　some　prior　reliable　information　to　reduce　complexity　and　improve　performance　of　Viterbi　algorithm　(VA).　However　it　can　only　be　used　in　the　concatenate　code　scheme　because　the　detection　result　of　cyclic　redundancy　check　code　(CRC)　is　exploited　to　provide　reliable　information.　In　this　paper,　a　different　way　is　proposed　to　provide　reliable　information　for　C-VA,　which　is　possible　to　be　used　in　simple　codec.　Known　bits　were　added　to　the　set　partitioning　in　hierarchical　trees　(SPIHT)　coded　image　sequence　periodically　and　directly.　They　were　thought　to　be　reliable　information　for　C-VA　in　the　decoder.　Experimental　results　show　that　the　proposed　scheme　can　obtain　much　better　error　resilient　ability　compared　with　conventional　VA　under　the　extremely　inferior　channel　condition　if　the　best　desired　quality　of　reconstructed　images　can　be　sacrificed.　©　2008　Shanghai　University　and　Springer-Verlag　GmbH.