Which processing step in digital radiography adjusts brightness and contrast after image acquisition?

• A. Histogram equalization
• B. Edge enhancement
• C. LUT application
• D. Windowing

Answer: (C)

After acquisition, the image must be converted into displayable grayscale by mapping the recorded pixel values to display levels. This mapping is done through a Look-Up Table, which assigns each input value a corresponding output value. The chosen mapping determines how bright the image appears and how wide the range of gray tones is, so it directly sets overall brightness and contrast.

Other processing steps either aim at different goals or alter the image in ways that don’t define brightness and contrast in the same way: histogram equalization reshapes the histogram to enhance contrast but isn’t the standard post‑acquisition control for clinical DR; edge enhancement boosts edges and sharpness rather than brightness/contrast; and windowing is a display control that adjusts the window level and width to emphasize a particular gray range, which is typically realized by selecting a different LUT or its parameters.