Figure 3: High-resolution images of microspheres are used to validate results of model-based processing on working-resolution images. High-resolution (63x) (a) and working-resolution (7x) images (b, c) of green fluorescent microspheres were obtained. There is a two-microsphere cluster in (a), which is visually ambiguous at the working resolution. The algorithm’s result for a two-cell cluster in (d) visually matches the image in (c). Other numbers of microspheres resulted in a much poorer fit to data. Note that 9 × 9 pixels in the high-resolution image correspond to 1 pixel in the low-resolution image and that the “grid” is not exactly maintained; that is, the 2D region in (a) only approximates regions in high-resolution images. The lower left microsphere in (a) is brighter than the other probably because it is closer to the surface.