Grey shading on LaserJet 4

[David Sumbler]

mike at easysw dot com wrote:
> David Sumbler wrote:
> > I run Fedora Core 4, using Cups v.1.1.23.  I have two printers, one of which is an HP LaserJet 4 with postscript.
> >
> > When I print a greyscale image using the Cups driver, I get a sort of "solarized" effect, with the greys stepped rather than having smooth transitions.  I even get fractal-type patterns in some places.  The same images print fine on my HP PSC 2210, also using Cups.
> >
> > Is it possible to get a decent result with the HP4?
>
> The on-board PostScript included with the HP LaserJet 4 uses a
> standard round dot halftone pattern; printing at 600dpi will make
> the pattern less visible, but if you want better shading you'll need
> to switch to a PCL driver like the one included with Gutenprint (aka
> Gimp-Print).

I have gimp-print v.4.2.7 installed as well as gimp-print-utils and gimp-print-plugin.  However, when I add a printer using the Cups web interface, after I click on "HP" for "Make", I am only presented with 4 items for "Model": "HP DeskJet Series CUPS v1.1 (en)", "HP LaserJet Series CUPS v1.1 (en)", which appears twice, and "HP New DeskJet Series CUPS v1.1 (en)".  This doesn't sound like what I should be getting.  Any suggestions as to what's wrong?

David