Open Access Images

The following sites maintain good lists of museums, galleries, etc. that provide images with open licenses or in the public domain.

• Open access image libraries – a list | Apollo Magazine
• High Quality Collections of Digitized Art and Archival Finds | simon sarris

The next resources seems to be meta-collections of open access images.

• Medium: Images – Collections – The Public Domain Review
• Artvee
• Public Domain Free Creative Commons Images | rawpixel

Next are some museums that allows you to search their image collections and filter the ones that are open access.

• Cleveland Museum of Art
• The Metropolitan Museum of Art
• The Art Institute of Chicago
• Rijksmuseum
• SMK Open
• Louvre site des collections

Next are social sites that allow individuals to upload and share their work with open licenses.

• Flickr: Creative Commons
• Beautiful Free Images & Pictures | Unsplash

This next resource is a "visual search engine" that allows you to search across several of the resources above.

• Museo

This last resource is a custom Google search engine created by Austin Kleon that searches across many of resources provided by the first set of resources above.

• Open Access Images Search Engine