[magick-users] shrinking huge blureprint images

[Carl Karsten]

I have a bunch of .pbm files that are scans of blueprints.  the scans are big - 
they create 1.4gig temp file when I work with them.  so I want to shrink them, 
but I keep 'loosing detail' like whole walls.

I think the problem is the thin black lines - if there is any trace of a line, I 
need there to be a line in the output.

I see this list of resize filters:

    Point
    Box
    Triangle
    Hermite
    Hanning
    Hamming
    Blackman
    Gaussian
    Quadratic
    Cubic
    Catrom
    Mitchell
    Lanczos
    Bessel
    Sinc

Which one should I use?

and/or, where can I find a description of them?

Carl K