Contrasts of the polymer materials under a high contrast X-ray computerized tomography (XCT) are comprehensively investigated. We developed a high contrast XCT, and demonstrated its capabilities to polymer systems, such as polymer blends. Then we got a hypothesis that the pixel values of the cross-sectional image obtained by XCT agree with the X-ray absorption coefficient at 15 keV. This hypothesis is intensively examined by using various polymers. Consequently, we propose an empirical criterion that 0.1 cm(-1) difference in the X-ray absorption coefficients at 15 keV is necessary to distinguish the polymers under XCT. This criterion is also confirmed in the polymer blend systems. (C) 2012 Elsevier Ltd. All rights reserved.