The integrated nature of CMOS sensors and modules reduces the number of components you need to include on your board. Although these sensors can provide low noise images, a sensor itself has high sensitivity to noise. Ripple and fluctuations in power supply voltage, EMI from other components, and noise coupling from the substrate can all induce noise in the output from a CMOS sensor, leading to grainy or noisy images. Significant ripple and transient undershoot or overshoot can also degrade image quality.
Some simple layout rules can help insure signal integrity and clear images.