Two kinds of inbuilt lens distortion correction?

Hello

I am new to shooting in raw format, and I am confused regarding lens distortion correction.
When i look at the photos in irfanview or in filebrowse mode in Rawtherapee, there seems to be no lens distortion at all.

But when i start using rawtherepee the picture gets distorted.

I have tried using the auto distortion correction, but the result is not as good as before opening the photo,

or just viewing them in irfanview

My question is: How do i export the distortion free photos, that irfanview and rawtherepy automatically shows before tampering with the them, to jpg format?

Kind regards
Erik

First you must understand what you’re looking at when you view the thumbnails or when you view the “raw” file in an external image viewer:

Once you read that, the question remains how to correct the distortion if the auto-correction is not enough - use an LCP or do it manually. RawPedia explains that.

Long story short, you’re seeing an embedded jpeg image, with in-camera distortion correction already applied to it (embedded in your raw file).

Opening the file in RT shows you the actual raw data, which you’ll then have to correct for distortion as @Morgan_Hardwood already pointed out. If you have a common enough body+lens then their might already be a lens correction profile (LCP) that you can use.