Second, GI simultaneously provides three complementary types of information about the sample. e absorption contrast relates to the “classic” x-ray image, which is based on variations of the linear attenuation coecient. e (dierential) phase contrast (DPC) is proportional to the (rst derivative of the) accumulated phase shi of the x-ray beam aer transmission through the sample. e DPC signal is mainly responsible for the high sensitivity of GI (McDonald et al., 2009). e so-called scatter contrast
(also dark-eld or visibility-reduction contrast) is a measure of the scatter strength of specic sample details (Pfeier et al., 2008), and its origin as well as its interpretation is the subject of ongoing research (Lynch et al., 2011; Yashiro et al., 2010). ese complementary contrasts can be taken advantage of in order to increase the ability to detect and discriminate between minute sample variations (Bech et al., 2010; Stampanoni et al., 2011).