The ones in Wikipedia (https://da.wikipedia.org/wiki/Hans_Dahl_(maler)) are rather low quality.
This case is so bad that one cannot even see her facial features: https://upload.wikimedia.org/wikipedia/commons/a/af/On_the_Mountaintop.jpg
In this one (https://upload.wikimedia.org/wikipedia/commons/2/27/DEN_UNGE_SL%C3%85TTEKAREN_.PNG) one can see pixelation very easily.
In this one, you can see an interference pattern that comes probably from being a scan of a print, rather than the original: https://upload.wikimedia.org/wikipedia/commons/6/6e/Dahl_Hans_%28Norwegian%29_1849_to_1937_By_The_FJord_O_C_49.5_by_67.3_cm.jpg
I am assuming this is in the public domain. Do you guys know better quality sources?
His page at nasjonalmuseet only has sketches. https://www.nasjonalmuseet.no/samlingen/produsent/54818/hans-dahl
by flying-benedictus