Contrast and Spatial Resolution Practice Test 2026 – All-in-One Resource for Mastering Exam Success!

Quantum mottle comes from the random arrival of photons, so at low exposure there are far fewer photons detected. That means the signal-to-noise ratio is small and noise appears as graininess in the image. This graininess makes subtle differences in gray levels harder to detect, reducing low-contrast detectability. It also masks fine, high-frequency details because those details rely on a stable signal to rise above the noise. In short, when exposure is low, quantum mottle degrades perceptual resolution by making the image noisier and less able to reveal both subtle contrasts and fine structures. It does not increase high-frequency contrast, nor does it simply brighten the image; it adds noise that obscures detail rather than enhancing it.