Troubleshooting poor print quality

[Anonymous]

Mike Paul wrote:
> I'm using a printer with CUPS which isn't in the Foomatic database (a
> Konica KL-3015 color laser, to be specific) and I've configured it by
> taking the PPD file shipped with the printer's Windows driver, and adding
> the following line in the appropriate place:
>
>   *cupsFilter: "application/vnd.cups-raster 0 rastertohp"
>
> (I want PCL output because this printer doesn't support PostScript.)
>
> Printing from Windows works fine -- the Windows clients (which have the
> Windows driver installed) submit jobs directly using IPP and they come out
> looking as I'd expect.  But when I try to print things using the "lp"
> command I get very poor-quality results; a plain-text file comes out
> looking like a fax, very low-resolution and with gaps in some letters (the
> left side of the loops in the letters 'p' and 'b' arent' closed).
>
> I want to troubleshoot this, but I'm not sure where to start.  I know the
> text is going through some filters and getting rasterized by CUPS, because
> the printer can print plain text just fine if it's sent raw; I
> believe the filter chain is (texttops -> pstoraster -> rastertohp) but I

Increase log level of cupsd daemon using the following /etc/cups/cupsd.conf directive :

LogLevel debug

/etc.init.d/cupsd restart

You should now have a lot of debug messages in the '/var/log/cups/error_log' log file, like the autotyping of your job file ('application/postscript', ...) and the filter pipeline ('texttops'->'pstops'->'pstoraster'->'rastertohp').

For resolution related problems, you could try to add the following PPD statements in your PPD file ('/etc/cups/ppd/your_printer.ppd') :

*OpenUI *Resolution/Resolution: PickOne
*OrderDependency: 20 AnySetup *Resolution
*DefaultResolution: 600dpi
*Resolution 150dpi/150 ppp: "<</HWResolution[150 150]/cupsColorOrder 0/cupsColorSpace 3/cupsCompression 2>>setpagedevice"
*Resolution 300dpi/300 ppp: "<</HWResolution[300 300]/cupsColorOrder 0/cupsColorSpace 3/cupsCompression 2>>setpagedevice"
*Resolution 600dpi/600 ppp: "<</HWResolution[600 600]/cupsColorOrder 0/cupsColorSpace 3/cupsCompression 2>>setpagedevice"
*CloseUI: *Resolution

Use the 'cupstestppd' command to validate your modified PPD file, and then restart the cupsd daemon and try again.

Regards.

> haven't been able to find any way to actually see what CUPS is doing as it
> processes the job, or look at the intermediate stages of output.
>
> I'm not concerned right now with the various settings in the PPD file for
> things like paper trays; I just want to get a look at what's happening to
> my job as it makes its way through CUPS processing.  Is there a way to do
> this?
>
> (I should note that I'm not looking for a solution which just passes plain
> text straight through; I do print PostScript and graphics from time to
> time, and need working filtering for these.)
> --
>
> Mike Paul
> mbp2 at lehigh.edu
> http://www.lehigh.edu/~mbp2/
>