Excel rendering produces low-resolution text compared to PDF when converting to JPG ( or PNG)

GroupDocs.Viewer Product Family
1

Hello,

We are using GroupDocs.Viewer for Java (v25.12) to render documents as JPG images.

While testing Excel rendering, we noticed that the image quality produced by our application is significantly lower than the result generated by the GroupDocs online conversion tool.

To illustrate the issue, we are attaching three files:

  1. Original Excel file
  2. JPGimage rendered by our application using GroupDocs.Viewer
  3. JPG image generated by the GroupDocs online conversion site

The image generated by the GroupDocs online conversion site has much higher text clarity and resolution compared to the image generated by our application.

Environment

Product: GroupDocs.Viewer for Java
Version: 25.12
Rendering format: JPG
Platform: Java / Spring Boot

Observed behavior

In our application:

  • Excel → JPG conversion produces lower text clarity
  • The table and text appear blurry or rasterized

However:

  • The same Excel file converted using the GroupDocs online conversion tool produces a much sharper image

This suggests that the online converter may be using different rendering options or higher resolution settings.

Files attached

We are attaching the following files for comparison:

  1. Original Excel file
  2. JPG rendered by our application
  3. JPG generated usingconversion.jpg (99.2 KB)

the GroupDocs online conversion site (Online XLSX to PDF converter | Free GroupDocs Apps )

The difference in rendering quality is clearly visible in these files.

Question

Is this difference expected because of a limitation in GroupDocs.Viewer, or are there additional rendering options that we should configure to improve spreadsheet rendering quality?

For example:

  • Is there a way to increase the rendering resolution for spreadsheets?
  • Is the online converter using different rendering settings internally?
  • Are there recommended options for high-quality Excel to image rendering?

We would appreciate any guidance on how to achieve rendering quality similar to the GroupDocs online conversion result.

Thank you.

excel-invoice.zip (12.5 KB)

conversion.jpg (99.2 KB)

viewer.jpg (76.4 KB)

2

Thank you for contacting us.

When comparing the GroupDocs.Conversion online converter and GroupDocs.Viewer for Java, the output quality may differ because they are different products running on different platforms.

Our online converter is based on GroupDocs.Conversion for .NET. Even when comparing GroupDocs.Viewer for .NET and GroupDocs.Viewer for Java, we can observe that the Java side currently produces slightly lower image quality. This behavior is related to an internal library that performs the conversion to JPEG. We can confirm that this quality degradation should be addressed. Our development team will analyze the issue and try to improve it in an upcoming release.

If you are not already using the Quality property in your code, we recommend explicitly setting it to the maximum value:

JpgViewOptions.setQuality((byte)100)

By default, this value is set to 90, so increasing it may improve the output quality.

We will update you as soon as we receive feedback from our development team.

3

Thank you for your reply.

The attached sample already sets JpgViewOptions.setQuality((byte)100).
We hope this issue can be improved soon, as the quality difference compared to the online converter is quite noticeable.

Thank you for your assistance.

4

@cho_hyun ,

We have received feedback from our development team. They have already implemented a small fix that improves the quality of the resulting JPEG images, and this improvement will be available in version 26.3 of GroupDocs.Viewer for Java.

As you can see from the attached file, the output now has noticeably better quality.
invoice.jpg (112.3 KB)

Additionally, the team mentioned that they plan to introduce more configuration options for adjusting the quality of the resulting documents in future releases.