Paint.NET image

File Format
Name	Paint.NET image
Ontology	Electronic File Formats Graphics Paint.NET image ; ; ;
Extension(s)	.pdn

Paint.NET image (or PDN) is the native graphics file format of the Paint.NET image editor for Microsoft Windows.

Identification

Files begin with a signature: the ASCII characters "PDN3".

Paint.NET official site (which, confusingly enough, isn't actually at paint.net itself, which belongs to an actual paint company!)
Lazpaint