What does modulation transfer function quantify in imaging?

• A. It measures the brightness of the image.
• B. It measures the accuracy of reproduction across spatial frequencies.
• C. It measures the geometric distortion of shapes.
• D. It measures the color depth of the image.

Answer: (C)

MTF measures how accurately an imaging system reproduces image contrast as the level of detail changes. Spatial frequency corresponds to how fine the pattern is: low frequencies are large, broad features, while high frequencies are fine textures. The MTF is the ratio of image contrast to object contrast for different spatial frequencies, typically shown as a curve. A system that preserves contrast across frequencies well will have an MTF that remains high at more frequencies; real systems show a drop-off at higher frequencies due to blur, diffraction, and aberrations. This is a direct way to quantify sharpness and resolution. It’s not about brightness, geometric distortion, or color depth.