Pdf to image conversion: quality degradation and significantly increased file size

Hello, dear GemBox support team,

We use GemBox.Pdf’s PDF → Image conversion functionality to generate thumbnails.

After a fairly recent update, we noticed a degradation in image quality for text-heavy documents (it appears that original fonts and/or their weights are no longer preserved), as well as a significant increase in the resulting image file size (two times or more).

In production, we typically extract relatively small thumbnails (up to 320×320 px). However, for demonstration purposes, I generated larger images to make the issue more visible.

The GemBox versions used are:

  • “Old” version: 2025.10.106
  • “New” version: 2026.1.107

Result from the “old” version:

Result from the “new” version:

For reference, here is how the original PDF document looks (I can share the PDF file itself if needed):

The difference in image file size is also quite noticeable: approximately 55 KB in the old version versus 130 KB in the new one.

Could you please advise what might have caused this change (both in visual appearance and file size), and what options are available to restore the previous behavior?

Thank you in advance.

Hi Yaroslav,

Please send us your PDF file so we can investigate it. You can send it via email or support ticket (see the Contact page).

Regards,
Mario

Hi,

Please try again with this NuGet package:

Install-Package GemBox.Pdf -Version 2026.1.111

Note that this is a hidden (unlisted) version. To install it, you’ll need to run the above command on the NuGet Package Manager Console (Tools → NuGet Package Manager → Package Manager Console).

Does this solve your issue?

Regards,
Mario

Hi Mario.
Thanks a lot, the issue seems to be resolved with the latest versions of the GemBox components.