The human visual system, and almost every digital camera, achieves trichromacy by using sensors of different spectral sensitivity arranged in some spatial pattern. What pattern of spatial sampling is best? I’ll describe work on learning an optimal (ok, locally optimal) color filter array. This learned sampling pattern leads to better reconstructions of color images than the Bayer pattern and many others. If there is time, I’ll talk about some issues in sampling over time, and show simulation results for a camera that can both add and subtract from a pixel intensity counter.