The present invention provides a method and apparatus for reducing uneven brightness in an image from a particle based image system. This uneven brightness is most often seen as regions of shadow, but may also be seen as regions of over brightness. In cases where the uneven brightness is in the form of shadowing, the method corrects for the shadowy regions by first identifying the area of shadow, obtaining brightness information from a region near the shadow, where the brightness is optimal, applying statistical methods to determine the measured brightness as a regression function of the optimal brightness, and number and proximity of shadowy objects, then correcting the shadow area brightness by calculating the inverse of the function of the shadow brightness. With this method, the brightness within the shadowy or over brightness regions are corrected to appear at a substantially similar level of brightness as the region of optimal brightness in the image.