Which term corresponds to the overall darkness of a radiographic image, analogous to brightness in digital imaging?

• A. Density
• B. Contrast
• C. Exposure
• D. Brightness

Answer: (A)

The overall darkness of a radiographic image is described by density. In film radiography, density is the degree of blackening on the film—the more exposure and processing, the darker the image appears. This is the radiographic counterpart to brightness in digital imaging, which refers to how dark or light the image looks on a monitor. Contrast, on the other hand, measures the difference between light and dark areas; exposure is the amount of radiation used to create the image (which influences density but is not the darkness itself); and brightness is a digital-display adjustment, not an intrinsic property of the film image. So the term that best matches the concept of overall darkness is density.