Formatting Issues

How to Remove Gray Borders Around PNG Images in PDF Files

Khadija Khan Oct 19, 2026 869 views

Question details

Users experience unexpected gray borders appearing around PNG images when exporting documents containing PowerPoint elements into PDFs.

How to Remove Gray Borders Around PNG Images in PDF Files

Product: Microsoft Word, Adobe Acrobat Pro
Device & OS: not provided
Scenario: Converting a Word document with inserted PNG images to a PDF file using Adobe Acrobat Pro.
Observed behavior: Gray or dark outlines appear around PNG images in the exported PDF, despite these borders being completely invisible in the original Word or PowerPoint files.

Before you start

Check if your PNG images have a transparent background, as PDF rendering engines occasionally struggle to process the alpha transparency layer correctly, resulting in visible artifacts.

Solution 1Recommended

Use Microsoft Word's Built-in PDF Export Feature

Bypass third-party add-ins by using Microsoft Word's native export tool to prevent image transparency rendering issues.

The gray borders are often caused specifically by how the Adobe Acrobat Pro conversion add-in processes image transparency. Using the native PDF creation tool in Microsoft Word bypasses this rendering engine and preserves the image exactly as it looks in the document.

Open your document

Launch Microsoft Word and open the document containing the affected PNG images.

Navigate to Export

Click on the 'File' tab located in the top-left corner of the window, then select 'Export' from the left sidebar menu.

Create the PDF

Click the 'Create PDF/XPS Document' button. Choose your destination folder, ensure 'PDF' is selected in the 'Save as type' dropdown menu, and click 'Publish'.

Use Microsoft Word's Built-in PDF Export Feature

Native Conversion Recommended: Using Word's native exporter is generally more reliable for handling transparent images than using external printer drivers or plugins.

Solution 2

Convert PNG Images to JPEG Format

Change the image format to JPEG to remove the transparency channel that causes the gray borders during PDF conversion.

Seamless PDF Conversion

Convert Documents to PDF Flawlessly Using WPS Office

WPS Office offers a robust built-in PDF converter that seamlessly handles image transparencies, ensuring your PNG images export without unwanted gray borders or artifacts.

1. Open Document: Launch WPS Writer and open the document containing your transparent PNG images.
2. Access PDF Export: Click on the 'Menu' button in the top-left corner and select 'Export to PDF'.
3. Generate PDF: Adjust your preferred export settings in the dialog box, then click 'Export' to generate a clean, artifact-free PDF.

Flawlessly exports documents to PDF without transparent image rendering glitches.Highly compatible with Microsoft Word (.docx) and PowerPoint (.pptx) formats.Free and lightweight office suite with familiar, easy-to-use formatting tools.

microsoft office alternative - wps office

Frequently Asked Questions

Why do transparent PNGs get gray borders in PDFs?

This happens because certain PDF conversion engines or third-party plugins struggle to properly render the alpha channel (the transparency layer) of PNG files. As a result, the edge pixels where the image meets the transparent background are incorrectly calculated, appearing as a dark gray outline.

Does this issue happen in all PDF viewers?

The severity of the borders might vary slightly depending on the PDF viewer (like Adobe Reader vs. a web browser). However, because the artifact is physically rendered into the image data during the conversion process, it will typically show up in most standard PDF readers.

Can I fix the gray borders without replacing the images?

Yes. If you prefer not to convert all your images to JPEG, the easiest fix is to avoid using external PDF creator plugins. Instead, use your word processor's built-in 'Save As' or 'Export' to PDF features, which usually process image transparency much more accurately.

Document & File Issues