do you mean dp's?
if you do, this is the only way i seem to be able to reduce the size of a screenie without it getting all messed up
first, open up your screenie
go to canvas > change resolution > (if you took a *hiresnobg it should be something around 2048x2048)
what i do now is change this usually to around 900x900 (i always change to either 700, 800, 900 or sometimes 1000 depending on how large the screenie is, however i edit as 320x440 so if you edit on a 160x220 then the 900 should go down to something like 600)
i then go to canvas > change size > 320x440
once i've finished editing, i'll bring this down to 160x220
as far as i know, this is the only way to bring down the size without fuzzyness
i hope this helped!