This disclosure describes techniques for initially calibrating an image capture device. According to one aspect, the calibration includes calibrating parameters of an image filter for resolving the captured image. The method includes receiving a captured image of a test target and resolving the captured image using a set of initial parameters. A sharpness index of the resolved image is determined without matching the captured image to the test target. The sharpness index is used to minimize a cost function for determining parameters for use by the image capture device.