Print quality DHL Label


#1

Hi,

i try to print some DHL Label PDFs via Sumatra. But the quality of the label is very bad.
I’m using a Zebra Printer.
Is there a way to improve the printing quality?

thanks

Alex


#2

@alex-LE Very difficult to say how it can be improved without knowing the zebra model/driver options

the lack of quality is possibly due to the source info, can you provide a sample pdf without personal details?

bottom line is that thermal printers expect a specific resolution that matches their printhead spacing (often 8 dpmm = ~203 dpi but may depend on model e.g. 12 dpmm =~ 300dpi ), otherwise the print driver software is often likely to make a poor approximation as an example see the folowing a typical lable
fedex-label-50a

and the results of printing 200 dpi at 300 dpi and vice versa (both will result in unreadable bar codes)
fedex-label-50c fedex-label-50b
for a typical configuration see https://help.postmen.com/hc/en-us/articles/115010761748-Setup-Zebra-thermal-printer-on-Windows

I note from DHL site

“You need a laser printer to print your waybills and customs paperwork. We highly recommend you use a laser printer rather than ink jet to ensure barcode quality on the waybill. Barcodes printed by ink jet printers can cause scanning problems which could result in delivery delays due to additional manual processing. Use a laser printer and you’ll avoid this problem”

Also
You can receive label(s) in PDF format, or for Thermal printing:

DHL labels for thermal printing OR DHL label in PDF

Labels for Thermal printing you can send directly to printer.


#3

Using the older Sumatra version 3.0 might help, but basically even the developer seems to admit that Adobe Reader or other PDF apps do a far better job with printing.


#4

@GitHubRulesOK - thanks for your answer!

Unfortunately the current DHL Webservice just returns a PDF, a thermal printer version would be great.
I will contact them directly and ask. In the mean time i have to work with the pdf.

Here is a example pdf. https://we.tl/8NPRnaMDol

I’ve tried to print it with Adobe, the result is perfect.
But Adobe does not have a silent printing option (i’m building a nodejs printing server on windows - for internal use).
Foxit has such a option, but only in a older version (6.2). The result is good too, but i’m not sure if it is a good idea to use such a old version.
I would prefer using Sumatra, but the result is really bad, the barcodes are readable (tested with an iPhone) but it does not look very good (like your 200dpi example).


#5

thanks for the sample
It is certainly NOT well set for thermal use, there are many factors that will have an affect
the file is Textual with a few barcode images, by default Adobe will see it graphically as approx 72 dpi and will apply lots of math to ensure it is matched to the printer resolution possibly without anti-aliasing, SumatraPDF is based on MuPDF which attempts to anti-alias (smooth out for the readers benefit) fonts and image, when convered back to monochrome pixels it will have the opposite effect of making it look “blocky”.
For this reason DHL used to supply ZP# files for thermal printers

The key is ensuring scaling is “Matched”,
can you confirm via the print driver that SumatraPDF uses that it is set to the resolution of the printer eg 203 dpi for a zebra #20 or 300 dpi for a #30, which model are you using, does it have the latest correct driver ?
did you try the seagull driver from the link above,
Are the lables the correct size, the thermal printer standard was often 4" x 6" (not A5 as per sample)


#6

I agree you should NOT use a V6 Foxit in light of recent exploits and you are using external PDFs from a high profile 3rd party (DHL) however although I have not used acrobat in a long while I thought all prior versions respected the /t command, using acrobat version 9 with
AcroRd32.exe /t test3.pdf “Microsoft XPS Document Writer”
pause
taskkill /F /IM acrord32.exe
I got

You can roll your own print handler using Ghostscript and port redirector such as Redmon
However it may be easier to use a current maintained dedicated commercial product that respects DPI such as biopdf e.g. trial copy updated 2018-05-06 (version 11.7.0.2716) note there are many others available.


#7

I’ve stopped the work for now. DHL told me that its currently in progress to get a ZPL version of the label, so i will wait for that.
Acrobat basically worked, but its not that fast. Currently i convert the pdf to a image using imagemagick, thats slow too but as long as it doesn’t take so long we can use this until the zpl version.

thanks for your help!

Alex