Bug 458722

Created attachment 151820 [details]
PDF test file for Data Matrix Code

SUMMARY
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STEPS TO REPRODUCE
1. Open with Okular a PDF file which contains small Data Matrix Codes (similar to QR Code)

2. If this Data Matrix Code is small then you will notice a bad rendering (blurry rendering), much more noticeable when printing on black and white laser print.
3. Open the same PDF with another PDF reader (Xpdf, firefox PDF reader) : you will notice better rendering, sharp rendering

OBSERVED RESULT
Blurry Data Matrix Codes on screen display and on black and white laser print for small Data Matrix Code

EXPECTED RESULT
The Data Matrix Code should be sharp, like other PDF reader.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch linux
(available in About System)
KDE Plasma Version: 5.25.4
KDE Frameworks Version: 5.97.0
Qt Version: 5.15.5

ADDITIONAL INFORMATION
Another way to reproduce the problem : buy PDF stamps on french La Poste website :
https://www.laposte.fr/mon-timbre-en-ligne

These stamps have small Data Matrix code, Okular doesn't manage to display them with accuracy, we can see blurry rendering, both on screen and on laser print.

You can also open the attached file "GS1_DataMatrix_Guideline.pdf" with okular, on page 20 you will notice that the data matrix code is bad rendered (blurry areas)
if you compare with PDF firefox reader or Xpdf the rendering is much better.

Data Matrix code on wikipedia :
https://en.wikipedia.org/wiki/Data_Matrix