Abstract: The performance of filtration materials was controlled by their pore opening size distribution(PSD).Most of the current methods for determining PSD were indirect and contained inherent disadvantages.Recent technological advancements in image analysis offered great potential for a more accurate and direct way of determining the PSD of filtration materials.The present digital image analysis method was developed with various mathematical morphology algorithms.An original program was compiled in Matlab with this method to provide a complete PSD curve for filtration materials.