Tiff monchrome memory usage

[David Stevenson <david avoncliff com>]

Hi
I have a problem, and am not sure where to ask, so if this is the wrong 
place please advise.

I am using tiff files that are 9000x6000 pixels black and white.
( they are schematic drawings intended to print A0 size )
I calculate this as just under 8meg at 1 bit per pixel, however when I 
open in Gimp or Eye of Gnome they seem to use over 200meg of ram, which 
pushes my 256meg Macmini into swapping and makes the files unusable.

I thought the problem could be with the files claiming to be 24bit 
colour although only using mono, but from a quick look at the headers I 
think they are 1 bit / pixel.

Can anyone confirm the memory use for black and white tiffs.


David