Somebody told me once that pictures don't have subjects because of the is-ness about-ness separation:

I disagree. Here are some things from the literature.

https://drum.lib.umd.edu/bitstream/handle/1903/15063/Describing_Visual_Materials_in_the_Digital_Age_Hamburger.pdf

http://duspeccoll.github.io/local_authority

https://journals.ala.org/index.php/lrts/article/viewFile/7564/10462

https://listserv.loc.gov/cgi-bin/wa?A2=ind0501&L=MARC&P=4254

https://inevermetadataididntlike.wordpress.com/category/library-of-congress-genreform-terms/

http://netanelganin.com/projects/lcgft/lcgftType.html

https://cornerstone.lib.mnsu.edu/cgi/viewcontent.cgi?article=1000&context=olac-publications

https://www.isko.org/cyclo/subject