A process for operating an optical scanning system includes making an image of a sample by scanning spots in the sample, measuring intensities of light emitted by the scanned spots, determining locations of the scanned spots, and assigning intensities to image pixels based on the measured intensities and determined locations of the scanned spots. In the making of the image, the acts of determining depend on a value of a parameter. The process also includes selecting a new value for the parameter and deciding whether the image of the sample has less double imaging if the new value of the parameter is used during the acts of determining. The process accepts the new value of the parameter in response to determining that the new value produces less of the double imaging.