Which feature of digital imaging improves spatial resolution?

In digital imaging, spatial resolution refers to the ability to distinguish small objects or closely spaced structures within an image. A crucial factor that influences spatial resolution is pixel size; smaller pixels can capture more detailed information because they occupy less physical space and can represent finer details of the anatomical structures being imaged.

When the pixel size is reduced, the overall resolution of the image increases, since more pixels can fit into the same area. This increase in the number of pixels enhances the system's capacity to depict subtle variations in the anatomic details, thus improving clarity and the ability to differentiate between two closely located structures.

The other features listed, while important in digital imaging, do not directly serve to enhance spatial resolution in the same way pixel size does. Contrast resolution relates to the system’s ability to distinguish between varying levels of tissue densities, dynamic range pertains to the range of exposure levels that the imaging system can capture, and bit depth refers to the number of bits used to represent each pixel's color or gray level, affecting the range of tones rather than spatial detail.