The project is a thesis work in master program of Intelligent Systems that’s done by Alireza Mozaffari and Kunal Varaiya with supervising of Dr Kenneth Nilsson and Dr Cristofer Englund. In this project we are estimating the depth distribution of different sizes of fibers in a press felt sample. Press felt is a product that is being used in paper industry. In order to evaluate the production process when press felts are made, it is necessary to be able to estimate the fiber sizes in product. For this goal, we developed a program in Matlab to process X-ray images of a press felt, scanned by micro-CT scanner that is able to find the fibers of two different known sizes of fibers and estimates the depth distribution of the different fibers. / The project is done in Matlab which is estimating the distribution of different sizes of fibers in press felt.