Low signal-to-noise ratio results in what effect on the image?

• A. Higher quality
• B. No effect on quality
• C. Lower quality
• D. Increased noise visibility

Answer: (C)

When signal-to-noise ratio is low, the signal that represents the true image is weak compared with the random noise present. This makes the image look grainy and reduces the visibility of fine details and contrast, so the overall image quality suffers. In other words, the image is degraded because noise dominates the signal. You may also notice that noise becomes more visible, which is a symptom of the low SNR, but the primary effect is a drop in image quality.