An under-exposed image might exhibit which of the following artifacts?

An under-exposed image is characterized by insufficient light reaching the imaging receptor, which can lead to various visual artifacts. The correct answer is mottle, which refers to a grainy or splotchy appearance in the image due to an uneven distribution of exposure. This often occurs because the low exposure levels do not adequately capture detail, causing variations in pixel brightness that manifest as a mottled pattern.

Mottle can result from factors like low radiation dose or inadequate imaging technique, highlighting the importance of proper exposure settings in achieving high-quality images. It is particularly noticeable when the brightness levels are compressed, resulting in poor contrast and visibility of details, which is a common pitfall in under-exposed images.

In contrast, other artifacts such as ghosting (which involves the persistence of previous images or structures), blurring (due to motion or improper focus), and overlapping (which may occur from improper imaging techniques or positioning) do not specifically arise from the condition of under-exposure itself. These artifacts are related to different issues in image acquisition and processing, rather than the exposure levels that primarily cause mottle. Thus, mottle is the artifact most directly associated with under-exposure.