Thanks for the kind advice, Rhossydd. It made me think about where I might have gone wrong.
Upon further research and consideration, why am I trying to figure this out myself??
You folks (on Luminous Landscape forums) have been having recurring debates about fair usage?
How about consulting someone else, (for example, someone who must get it right) like wikipaintings.org?
This is Wikipaintings.org's official worldwide position, based on their legal counsel.
The site presents both public domain artworks and works that are protected by copyright. The last ones are posted on the site in accordance with fair use principle, because:
They are historically significant artworks;
The images are only being used for informational and educational purposes;
The image are readily available on the internet;
The images are low resolution copies of the original artworks and are unsuitable for commercial use.
Based on these principles, they are posting lo-res captures of (for just one example) Picasso's in-copyright art and no one is challenging them.
Now, I happen to believe that the membership of Luminous Landscape Forums are experts in the field, so asking questions of experts in the field falls under 'educational purposes'.
Since I can't afford legal counsel of the stature that an expert in their field (wikipaintings.org) can, I think I will 'borrow their (wikipainting.org's) homework'.
So. feel free to diss me after you feel up to taking on wikipedia.org's and wikipaintings.org's position on this topic.