[GRASSLIST:6868] crop of raster, size of raster

[Axel Orth]

hey list,
i just figured out that "cropping" of raster maps by the creation of a 
MASK and r.mapcalc is not exactly what i really intended:
i though the resulting maps are really clipped but it looks like the 
regions outside the mask are just white.

this is ok for me for one kind of rasters (have disturbing legends and 
annotations) but does not work for other maps.
is there a possibility to do something else?

by doing those operations i recognized also that the size of my data 
increases rapidly:
i import a 4 mb tiff (black and white) and by exporting it via 
r.out.tiff its size is 514 mb.
what could be the reason for this?

regards
axel