We are developing a technique of X-ray imaging capable of identifying materials in the image. The presented technique is based on analysis of two or more images taken using different energy discrimination thresholds with a single photon counting imaging detector, Medipix2. The Medipix type detectors are devices suitable for material resolving imaging thanks to their energy sensitivity for individual photons, allowing transmission to be measured as a function of X-ray energy. The material recognition technique presented here uses the signal-to-thickness calibration method and can be applied to images collected with an X-ray tube without the use of filters.