If stripes appear in a smooth area in an image, you can use the Noise Tool to get rid of them.
- Launch the Adobe Illustrator software and select the object you want to work with.
- In the Adobe Illustrator menu bar, in the Effect menu, select Prinergy > Noise.
The Noise dialog box appears.
- Set the parameters.
- Resolution: Determine the degree of Noise detail.
- Noise: Determine the size of tiny noise.
Type:
No Blur 
Gauss Blur 
Average Blur 
- Range: Define the area in the range where noise can be added.
- Antialias: If the anti-aliasing is set to None, you can avoid gaps in the edges of the adjacent objects.
- Object: You can add noise to specified objects (containing Group).
- Click OK.