To represent structures with small dots and uniform region with big dots

Problems with vector graphics and image: have different visualization. How to match them?

To preserve structure by using small stipples:

(1)A map for showing deviation, lighter area has higher structure.

(2)Vary stipple sizes. If it has higher deviation, use small stipples. If it is a uniform and close to black region, use largest stipples. Others are based on the intensity.

(3)Vary stipple sizes and remove stipples if they are sticked together.

(There are some vector graphics shared on google docs with you.)

(4)Only by choosing different scaling function to adjust the density.

(There are some vector graphics shared on google docs with you.)