why are some gimp images printing too light?

[joe]

.
When I print some images from Gimp or Kview or OO-Writer, 
images that appears solid black on the screen and when 
exported as pdf files, print grayed out (like about 50%) 
when printed to my HP 4 laser printer.  The laser printer 
is working fine and is printing solid black just fine from 
some other images and other applications.  I cannot find any 
settings in printer or document setup that might be causing 
this problem. 

Any suggestions how to chase down this problem?