In digital radiography, the adjustment of brightness and contrast is achieved through which processing step?

• A. Histogram analysis
• B. Rescaling
• C. Lookup table adjustments
• D. Digitization

Answer: (C)

Brightness and contrast are controlled by remapping the raw pixel values with a lookup table. In digital radiography, the detector’s digitized values are transformed through a LUT to display grayscale, and this LUT is where window level (brightness) and window width (contrast) are applied. By adjusting the LUT, you change how light or dark the image appears and how much tonal range is shown, without altering the original detector data.

Histogram analysis may inform what window settings to use by describing how pixel values are distributed, but the actual adjustment is done by applying the lookup table. Rescaling shifts the data range but isn’t the standard method for day-to-day brightness/contrast control, and digitization is the process of converting the analog signal to digital form, not the display adjustment itself.