Using Suse 9.1 and Cups: Laserjet4Si: using recommended driver Foomatic hpijs.
Graphics print too faintly with this driver. This problem was recognised in earlier versions of the driver and reported as now fixed.
The odd thing is, everything prints nicely from the commandline (lpr filename, as root), but not when I print from an application, (either direct to printer, using lpr in the app's print dialogue, or using kprinter.)
Does lpr process the job in a different way?
I have read all day about cusps and lprng -- but I still do not know exactly where to start looking to get to the bottom of this.

Everything uses CUPS.

Check the command being used by the applications - it should be lpr with options.

Then I suppose there is always: http://localhost:631/documentation.html

Hi Simon,
Thanks for your reply.
I gave up on the hpijs driver and changed to one called ljet4
Fixed the problem, so I suppose it is a glitch (still) in hpijs.
But it still annoys me that I couldn't figure out why printing from the command line would produce a better result than printing some other way, such as using lpr as the print command in acrobat, that I think of as being the same procedure.
Never mind, there is a great number of variables in the print system -- too many to pick through one by one.