Paint Net Alpha To 255 Plugin Download ((link)) -

How to Set Alpha to 255 in Paint.NET: The Ultimate Plugin Guide

The plugin most commonly used for setting alpha to 255 (making semi-transparent pixels fully opaque) is known as Transparency (part of the BoltBait pack) or Alpha Transform

• Layer → Rotate/Zoom → check "Cubic" resampling (not exact)
• Or flatten the image, then use Adjustments → Brightness / Contrast on the alpha channel?
  But honestly, the plugin is much cleaner.

If you prefer not to install external plugins, you can achieve a similar effect using built-in features: paint net alpha to 255 plugin download

Happy editing 🎨

Step‑by‑step download: