IrfanPaint is a plug-in that adds painting features to IrfanView and which is freeware. With the Plugin installed, you can do many basic photo-editing tasks without opening an external editor. As of 4.10 it is part of the supported plug-in package.
As it is provided by a different coder than IrfanView, the most recent versions can be obtained on the page stated below.

Nice plug-in for IrfanView (Freeware Picture View, which I already recommended earlier here:
If you’ve got IrfanView installed I suggest you should also install this plug-in for easy day-to-day picture editing tasks.