If a chest radiograph is taken with a lower mAs than appropriate, which digital process is used to display the image as if the receptor was exposed correctly?

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

Answer: (B)

When the exposure is lower than ideal, the digital system can adjust how the captured data are displayed by rescaling the pixel values. Rescaling stretches the recorded signal across the display’s available brightness range so the image looks as if the detector had been exposed correctly. This uses the image information (often referenced to the histogram) to map the weak signal to a standard range, boosting apparent brightness without changing the actual recorded data. While histogram analysis and LUT adjustments play roles in how brightness and contrast are ultimately presented, the specific correction for underexposure described here is rescaling. Digitization is just the conversion from analog to digital and isn’t the display correction in this scenario.