Figure 6: Contingency table analysis of algorithm accuracy on microsphere images. Microspheres/cluster were estimated using the algorithm on working-resolution images (7x). An expert visually determined the number of microspheres/cluster on corresponding high-resolution images (63x). Table entries are the number of times a result was obtained; for example, the algorithm and expert identified the same 2-cell clusters 38 times. In all cases but one, the algorithm was within ±1 microspheres. The total number of microspheres counted by the expert was 499 compared to 497 by the algorithm.