Spiral　Architecture　(SA)　is　a　relatively　new　and　powerful　approach　to　machine　vision　system.　The　geometrical　arrangement　of　pixels　on　SA　can　be　described　as　a　collection　of　hexagonal　pixels.　However,　all　the　existing　hardware　for　capturing　image　and　for　displaying　image　are　produced　based　on　rectangular　architecture.　Therefore,　it　becomes　important　to　find　a　proper　software　approach　to　mimic　SA　so　that　images　represented　on　the　traditional　square　structure　can　be　smoothly　converted　from　or　to　the　images　on　SA.　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　bilinear　interpolation　of　pixel　values　on　a　simulated　SA.　Our　experimental　results　show　that　the　bilinear　interpolation　improves　the　image　representation　accuracy　while　keeping　the　computation　simple.