What is the function of a look-up table (LUT) in DR image processing?

• A. Maps raw pixel values to display luminance to optimize contrast.
• B. Encrypts patient data for secure transfer.
• C. Adjusts the exposure technique automatically.
• D. Removes all image noise.

Answer: (A)

A look-up table maps the raw detector pixel values to display luminance values. This mapping lets the processor apply a specific transfer curve—often representing windowing and gamma shaping—so the image uses the monitor’s full range and highlights the most clinically useful contrasts. In practice, the LUT converts the broad, raw detector data into a display-friendly range, so tissues of interest stand out and details are preserved across different exposures and devices. It isn’t about encrypting data, automatically changing exposure, or removing noise; those functions come from other processing steps.