Bug 755082

It would be useful if you could attach an output from printing troubleshooter.
https://fedoraproject.org/wiki/Printing/Debugging#Printing_troubleshooter

Created attachment 534811 [details]
troubleshoot.txt

output of Cups troubleshooting

Created attachment 534812 [details]
Printed on F-16

Printed from Firefox on F-16

Created attachment 534813 [details]
Printed on Windows XP

Printed with Firefox on Windows XP, same web page. Notice the poor font rendering on F-16 when compared to the same application and document on Windows.

The degradation in print quality first appeared in F-15, there was no noticeable differences in print quality between Fedora and Windows prior to F-15.

The troubleshoot.txt doesn't contain cups error_log.
1) cupsctl --debug-logging
2) systemctl restart cups.service
3) print the same file as before
4) attach the /var/log/cups/error_log

Could you also try to create another printer queue using
Brother MFC9840CDW Foomatic/Postscript
or
Brother MFC9840CDW Foomatic/pxlcolor
driver ? Is the print quality influenced ?

Print quality is the same with these:

Brother MFC9840CDW Foomatic/Postscript
Brother MFC9840CDW Foomatic/pxlcolor

Created attachment 534833 [details]
cups error log

Could this be a font selection issue? Suppose the font was not available, would another font be substituted which had problems scaling to the specified point size? It really looks like a scaling problem.

(In reply to comment #7)
> Print quality is the same with these:
> 
> Brother MFC9840CDW Foomatic/Postscript
> Brother MFC9840CDW Foomatic/pxlcolor

Another option would be some not-Foomatic Generic driver like
'Generic Postscript Printer'
or Gutenprint driver like
'Generic PCL 6/PCL XL Printer - CUPS+Gutenprint v5.2.7 Simplified'

(In reply to comment #9)
> Could this be a font selection issue? Suppose the font was not available, would
> another font be substituted which had problems scaling to the specified point
> size? It really looks like a scaling problem.

Could you attach the original file you have been printing ?

The original file I was using as the example is this URL, printed with Firefox

http://www.apachetutor.org/dev/request

Not sure why I picked that file, just happened to be the one where my frustration overcame my inertia :-) The problem is seen with plenty of other print jobs.

One of the problems with diagnosing the problem is there are so many components at play. Is it an issue with how Firefox generates printing? It it an issue with font selection? If it's a font issue is it occurring in the app, in the printing middleware or in printer driver? etc. etc. :-(

(In reply to comment #10)
> Another option would be some not-Foomatic Generic driver like
> 'Generic Postscript Printer'
> or Gutenprint driver like
> 'Generic PCL 6/PCL XL Printer - CUPS+Gutenprint v5.2.7 Simplified'

Could you also try these two before we start narrowing the problem down ?

Created attachment 535449 [details]
result of running pstops filter

AFAICT Brother MFC-9840CDW is Postscript 3 compatible.
So when the original file is postscript then only pstops filter should be involved.

The 'Running filters by hand' [1] procedure could look like:
1) print from firefox to postscript (name e.g. test.ps)
   check that test.ps looks good
2) export PPD=/etc/cups/ppd/Brother-MFC-9840CDW.ppd
   /usr/lib/cups/filter/pstops 1 'me' '' 1 '' <test.ps >pstops.ps
   check that pstops.ps looks good
3) lpr -P Brother-9840 -o raw pstops.ps

What do you think Tim ?

[1] https://fedoraproject.org/wiki/Printing/Debugging#Running_filters_by_hand

Yes, looks like that should work.

John, could you try printing the pstops.ps file attached in comment #13
with 'lpr -P Brother-9840 -o raw pstops.ps' ?

re comment #15, The attached pstops.ps file printed normally with good font rendering.

I have a theory, perhaps I'm going out on a limb, but humour me for a moment.

Suppose the library preparing the page to print generated a list of fonts necessary for the page and then asked the question "does the target printer have the necessary fonts?". If it does I'll send "raw" printing commands to the printer (e.g. set font, render string). Otherwise since the printer can't handle the font requirements I'll fallback to a software emulation whereby I use a native rendering library to render the page as an image and then send the image to the printer. Is that plausible? It doesn't seem to me that Postscript (or any other command language on the printer) is the one rendering the text.

Part of my problem is I don't know how Linux applications print. I presume they use the same graphics library (e.g. GTK, pango, etc.) they use for screen presentation but in "print mode" and allow the graphics library to decide how it will generate printer commands (perhaps even using an intermediate format in a manner similar to compilers??)

I strongly suspect CUPS is not the culprit here, rather the printing subsystem is doing what it's told to do by someone earlier in the pipeline. But I just don't understand all the steps which occur between hitting "Print" in an application and what is finally sent to the printer.

(In reply to comment #13)
> AFAICT Brother MFC-9840CDW is Postscript 3 compatible.
> So when the original file is postscript then only pstops filter should be
> involved.

Actually according to the error_log the input file is not postscript but pdf
so there's also pdftops involved.

And in my case printing http://www.apachetutor.org/dev/request from firefox to pdf and running pdftops filter on the result creates quite ugly postscript (something similar as in comment #3) so the problem is I think in pdftops filter (which just calls /usr/bin/pdftops from poppler-utils).

re comment #18, that would seem to make sense. I say that because yesterday I printed a PDF from Evince and it exhibited the same poor font rendering. I would expect a PDF sent to a Postscript capable printer to be sent as mostly unaltered Postscript commands (because my understanding is PDF and Postscript share a tremendous amount). But it appears as if when we print PDF something is getting in there and modifying what should be straight Postscript commands to render text.

How this also relates to why the problem is also seen when printing from Firefox is out of my league :-)

Ok, let's pass this around to somebody with better insight.

Summary to Marek:
When I print http://www.apachetutor.org/dev/request from Firefox to pdf (which looks good) and then run /usr/bin/pdftops on the result I get quite ugly (in my opinion) postscript file.

Hi,

the problem here is that the page contains images with alpha channel. The convertor converts the page as a raster because of that. This was already reported here:
https://bugzilla.redhat.com/show_bug.cgi?id=574118

and here:
https://bugs.freedesktop.org/show_bug.cgi?id=21723

This is a bug which will probably last for quite some time because upstream says that he will probably never get to fix it.
I will try to look at it at some point in future but not now.

Regards

Marek

P.S.: As a workaround you can remove alpha channel from the images on the page you are trying to print.
Or you can print the page to PDF and convert it manually with pdftops to PostScript specifying higher DPI manually (default is 300 dpi). This will produce big PostScript file.

re comment #21. I disagree this is a low priority issue. I can no longer print from Fedora because a large percentage of the print jobs are of such poor quality I have to throw the output into the recycle bin and go to a Windows box. Something changed recently which has exacerbated the problem significantly (perhaps transparency has been incorporated into more components?). Anyway, IMHO this really needs to get fixed sometime soon.

What is the status of getting this fixed? Fedora 17 is showing the exact same issues.

I'm still having serious print quality issues in Fedora.

The problem was identified 6 months ago.

2 months ago I asked for the status of a fix. I heard nothing.

I'd really like to know what's being done to get this problem fixed and what the scheduled date is for the fix to appear.

Thank you.

Same printer (Brother MFC-9840CDW), same quality problems.  Better with F-15, now very bad with F-17.

I would appreciate the courtesy of getting a reply to my query concerning the status of getting this resolved.

Add bug dependency references.

As far as status, I don't believe anything has changed since comment #21  (Marek can update/clarify as needed, of course).

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