I do not do bulk changes to artist artwork as you propose because I sometimes prefer to use my own custom curated artwork.
assumption confirmed… I thought this was the likely reason you didn't want to do a batch update.
When I first added artist pictures to my collection via the method I suggested, I was not overly thrilled with the results. Picture quality was inconsistent, but more importantly, picture aspect ratios were all over the place. Viewing a page with all the artist thumbnails was just a mishmash of different size pictures and not pleasing at all to look at. Perhaps this is something that JRiver can look into/fix?
On the plus side, the
get artist image from last.fm tool only adds an image if there is currently none (i.e., it will not replace existing pictures) - or at least that's what I found to be the case. Obviously anyone who already has custom artist images for a chunk of their collection should test on a small batch to verify before applying the tool to the entire collection!
What I ended up doing instead was using another media program which did an excellent job on my collection of approximately 1000 artists, and 30,000 songs. The aspect ratio was
always square, and for approximately 70% of the artists, the image was high-to-very high quality with an image size of 1000×1000 or greater. I then copy/pasted all the images from that program's artist image folder into MC's and overwrote what I had. About 25% of my collection still needs work - when I am motivated and have the time, I manually search for the best artist image I can find using DuckDuckgo, whose image search/filter tool is far superior to Google's.