Each photo has its own issues. Too light, too dark and the last washed out. I know of no good autocorrection in Irfanview for this.
http://stackoverflow.com/questions/5250409/imagemagick-auto-adjust-the-colours-of-an-image-a-la-other-photo-management-ap which was in the top 10 search on your topic is interesting since you can batch the work. The examples there look good. Not perfect but for free and automatic, not bad.
I have some photos that need editing; but while I'm pretty IT literate, photo-editing is not my speciality, so I'd really appreciate some guidance about the kind of edits I'll need to make to the photos. Generally, the photos either need lightening or darkening.
I have around 600 photos to edit, but have copied 3 typical examples to this link: https://www.dropbox.com/sh/rd6sett8z3h2fna/AAC92pGOSe3reXlhswGVZVlVa?dl=0
Would really appreciate some advice.

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