Paint.NET v3.0.5
At first excuse my very bad English
EXIFS RESOLUTION NOT UPDATED WHEN USE PIXELS/CM
When use résolution in pixels/cm in Image/resize dialog box (eg. 118 pixels/cm, that's equal to 300 pixels per inch )
and save image the exifs infos are 118pixels/inch !!!!
Paint.net don't convert in Exif infos 118 pixels/cm TO 300 ppp (... exactly 118 x 2.54 = 299.72)