Which factor reduces the clarity of images of discontinuities in a specimen?

Increasing the specimen thickness reduces the clarity of images of discontinuities due to the increased absorption and scattering of the radiation as it passes through the material. Thicker specimens have more material for the radiation to traverse, which means that some of the rays may be absorbed or scattered in different directions before they reach the film or digital detector. This can result in a more diffuse image and a reduced ability to distinguish fine details or small discontinuities.

In contrast, decreasing the focal spot size tends to improve image resolution by providing a sharper image with finer detail; increasing radiation energy may enhance penetration but does not necessarily improve clarity; and decreasing the source-to-object distance generally improves image sharpness by minimizing geometric unsharpness.