What term defines the difference in optical density between light and dark areas on a processed radiographic film?

• A. Brightness
• B. Fog
• C. Contrast
• D. Detail

Answer: (C)

Contrast is the difference in optical density between light and dark areas on a processed radiographic film. It describes how well structures are distinguished on the image: high contrast means a wide gap in densities with sharp black-to-white transitions and few midtones, making bone and air easier to separate; low contrast results in many midgray tones, making detail harder to see. This concept is distinct from brightness, which is how light or dark the image appears on a display, and from fog, which is unwanted overall darkening that reduces image quality. Detail refers to sharpness of edges and fine structures, not the overall density range.