Accurate subpixel detectors

We propose an original method for spots detection by use of grey levels approximation surfaces. Analytical function of exponential type give very high precision results on the localization of various shapes of spots : points, lines, cross lines. The application of our solution in the optical calibration of a CCD camera using a grid [5] provides a good precision a real images (errors standard deviation inferior to 0,012 pixels with an of-the-shelf camera 512×512 and 256 grey levels).