question about images

Hi all,
I have a problem with understanding how BLOB's
work in postgres. It seems as thoug I have to use

COPY BINARY table (imagefield) FROM 'absolutepath+imagename' ;

this ofcourse give the error

ERROR: COPY BINARY: file signature not recognized

so I have new went througt some doc's and found that
some header has to be appended containing some info about
number of instances and flags etc.

NOW: Is there anyway I can deal with loading images from
files into my database from within a pgplsql function, or do I have
to hack some C code AND install c-functions as well, or even worse 8)
do some scripting outside the database.... ???

Thankfull for any input,

regards,
DagG