With digital imaging systems, the primary factors affecting final image contrast are the

• A. histogram and look-up table (LUT)
• B. mAs and kVp
• C. SID and patient thickness
• D. detector type

Answer: (A)

In digital radiography, the final image contrast is controlled mainly by how the captured pixel values are processed after the exposure, not just by the exposure factors themselves. The histogram records how many pixels fall at each gray level, and the system uses this distribution to set the window width and window level—effectively deciding which range of shades will be emphasized. The look-up table (LUT) then maps those input gray values to display values, determining exactly how dark or bright each tissue appears. By adjusting the histogram interpretation and the LUT, you shape the displayed contrast across the image, balancing visibility of subtle structures with the overall tonal range. Exposure factors, geometry, and detector characteristics influence the raw signal and noise, but the displayed contrast comes from this histogram-driven processing and the LUT applied to those pixel values.