[ccp4bb] how to generate density map of selected residues

[jy]

Hi All,

I tried the "mask map" function in COOT to generate density map of 
selected fragment. However, the map looked much better than the original 
2Fo-Fc map. For example, weak density now became strong density.

I am wondering whether the mask map I generated using default is 
actually a Fc map? is there a parameter setting to make it reflect the 
true map?

Also, is there a way to select non-continuous residues other than a 
segment? or what is a better program to do the job?

Thanks a lot!

Jie Yang