Hexagonal　image　structure　represents　an　image　as　a　collection　of　hexagonal　pixels　rather　than　square　pixels　in　the　traditional　image　structure.　However,　all　the　existing　hardware　for　capturing　image　and　for　displaying　image　are　produced　based　on　square　pixel　image　structure.　Therefore,　it　becomes　important　to　find　a　proper　software　approach　to　mimic　the　hexagonal　structure　so　that　images　represented　on　the　traditional　square　structure　can　be　smoothly　converted　from　or　to　the　images　on　the　hexagonal　structure.　For　accurate　image　processing,　it　is　critical　to　best　maintain　the　image　resolution　during　the　image　conversion.　In　this　paper,　we　present　an　algorithm　for　bi-cubic　interpolation　of　pixel　values　on　a　hexagonal　structure　when　convert　from　the　hexagonal　structure　to　the　square　structure.　We　will　compare　with　the　results　obtained　through　bi-linear　interpolation　for　the　conversion.　Our　experimental　results　show　that　the　bi-cubic　interpolation　outperforms　the　bi-linear　interpolation　for　most　of　testing　images　at　the　cost　of　slower　and　more　complex　computation.