When detecting particulate radiation, such as electrons, with a pixelated detector, a cloud of electron/hole pairs is formed in the detector. Using the signal caused by this cloud of electron/hole pairs a position of the impact is estimated. Inventors found that, when the size of the cloud is comparable to the pixel size, or much smaller, the estimated position shows a strong bias to the center of the pixel and the corners, as well to the middle of the borders. This hinders forming an image with super-resolution. By shifting the position or by attributing the electron to several sub-pixels this bias can be countered, resulting in a more truthful representation.
Inventors further found that by spreading the image Moiré-effects and interferences in the image can be countered. As long as the image is a sparse image (almost all pixels representing one or no impact) this spreading is a reversible process. After spreading (effectively a spatial low-pass filtering) a high-pass filtering may be used to crisp the image.
It is noted that shifting and/or spreading the information over several image pixels should take place before adding the events per image pixel. When said spreading is done after combining detector images, information is lost. It is noted that shifting cannot take place after combining detector images.