Free to use if we credit Usask. Attribution required (but is not always done in banners where there is no place for attribution, and that seems to be okay so far). See the album of Top USask Photos for examples of high quality images.
This database contains "material relating to First Nations, Metis, and Inuit peoples, found in Saskatchewan cultural and heritage collections". To search for photographs specifically, click on Archives, then Format, then Photographs.
From the SPRI website: "One of the world's most comprehensive collections of historical photographs of the Polar Regions. It also holds a growing collection of modern photographs taken by scientists and researchers working in the field"
From the AINA website: "Collection consists of over 4000 photographs dating from the late 1800s through the 1900s. Consisting mostly of black and white prints, but also some negatives and slides, the bulk of the collection dates to the first half of the 20th century...Much of the content includes an emphasis on Inuit cultural life and various scientific themes such as geology, glaciology, archaeology, and oil and gas exploration."