Illumination variation, image distortion, and pixel non-linearity of mobile phone microscopy can be minimized.

A Variation in illumination across a clear field of view along the horizontal and vertical axes for an LED flashlight source evaluated with a 10×/0.25 NA objective and iPhone 4. B Distortion across a field of view, evaluated along a bar target with a 10×/0.25 NA objective and iPhone 4. A parabolic fit is superimposed on the data for both axes. C The measured pixel response (+) of an iPhone 4 and 10×/0.25 NA objective to changes in illumination intensity is nonlinear but can be corrected for the gamma encoding (o) to recover a linear pixel response (R2 = 0.999).