Affected InDesign versions:

I could reproduce it with InDesign 2022, 2023, 2024, 2025 and Prerelease 2025. From what I've found here so far, however, the problem has existed since at least 2020.

Reproduce:

• "Display Performance" set to "Typical"
• place a PNG or PSD with semi-transparent areas in InDesign (image for testing: semitransparent.png)
• export to PNG

This also happens if the PNG export is triggered before the document has been fully rendered and the "Display Performance" settings are set to ‘High Quality’. This therefore also affects automated processes, e.g. on InDesign Server.

Expected result:

• high quality output with correctly rendered transparencies (see png-export-expected.png)

Actual result:

• Stripes in the semi-transparent areas (see png-export.png)

Even worse:

• set the "Display Performance" to "Fast"
• only a gray box is in the exported PNG instead of the actual image (see png-export-fast.png)