Getting licenses and permissions for images used in a film

We are finishing a documentary and have a stack of still images that we have found in various places--many historical--and we need to do our best to find the owners of the images to request or purchase licenses/permissions for use of the images. However, we only have the images and, for some, the title of the image file. We need someone to research these images--putting them through google image, for example--to try and identify the owner we need to be in touch with.

This isn't about the freelancer obtaining the permission or license, just finding out where and to whom we must go to negotiate such permission or license. Here are three articles that explain the process:


https://www.pixsy.com/academy/image-user/verify-image-source-copyright-owner/

https://blog.tineye.com/find-copyright-owner-using-tineye/

https://www.quora.com/How-do-I-find-the-copyright-owner-of-a-photo