1. A method performed by a computing device for generating a statistic for a down-track location from an original reconstructed image frame and a post-processed image frame, the original reconstruction image frame and the post-processed image frame being different representations of the same sample collected for the down-track location, the image frames having pixels with values, the method comprising: calculating energy of the pixels in the original reconstructed image frame; calculating a spot energy from the values of post-processed image frame pixels within a spot; and setting the statistic based on a ratio of the spot energy to the pixel energy.