1. A method of finding a grid from a fluorescent image of an array of signal sources, comprising: finding the signal source centers; building lines connecting neighboring signal sources into hexagons; partitioning hexagon lines; finding the orientation angle of the array; finding row boundaries of the array; finding column boundaries of the array; transforming the entire array into an alignment with image frame (zero orientation angle); finding row grid lines on the transformed array; and finding column grid lines on the transformed array.