A few days ago i published a post about public domain images from the New York Public Library (click).
Since we're currently working on a packaging design for which we use vintage public domain drawings, i found a few other online resources that i'd like to share with you.

But firstly, since i might have brushed over it in my last post, let's get into..:

Copyright

      A lot of work goes into creating art. (duh)
To help artists like for example painters, illustrators, writers and photographers protect the fruits of their labour, humanity created Copyright laws in the 1954 Geneva Convention and 1923 Berne Convention.
      These laws can vary in different countries, but all boil down to one thing: if you created an original work of art, you're automatically the copyright holder for the piece and anyone else wanting to use it has to get in touch with you and strike a deal about using your work.
      In most countries the copyright expires 70 years after the creators' death (click) or 140 year after its first publication.

      This is all rather straightforward and fair: you wouldn't want to spend valuable time and resources on a painting, drawing, photograph or written piece and have somebody else pick it up and run with it. Especially if this gets into your way of earning a living with your creative work.

For more in depth information about copyright, check out this Wikipedia Article.

Public Domain and CC0

      But what if you're looking for images to use in your blog, a graphic project or for a new art piece?

      Important to start with: Many of the images that can be found online are copyrighted. That something is published on the World Wide Web and you can download it, does not mean it became free to use for everyone.
      Not everyone knows this and it gets a lot of blog-owners in trouble when they don't properly research the images they (re-)use.

      If you don't want to be at risk of doing anything unlawful, make sure you use images that are not or no longer protected by Copyright laws.

      There are two typed of copyright free images:

1. Public Domain: 

Usually old images and pieces of art of which the copyright expired (70 years after the creators' death) or that were created before copyrights existed. These can be used for any purpose (also commercial use) with no permission or credit necessary. All pre-1923 published works fall into the public domain.

and

2. CC0 (Creative Commons zero): 

The copyright holder has waived all rights of his/her work and it can be freely used for any purpose, similar to Public Domain. Usually newer pieces.

For more about public domain, here's an article from Wikipedia.

And here goes... The Round up:

(please note: some of these websites have both public domain images and other content, make sure you double-check for public domain status before using any image)

libraries and institutions:

The New York Public Library - over 700.000 digitized items from the collection. NB make sure you check the box 'public domain' on the left of the screen.

The British Library - more than a million images on Flickr. 

The Smithsonian Libraries - A selection of Book illustrations, photos, drawings and other images from across the libraries

museums:

The Met - over 200.000 images in the public domain

Hermitage - NB note the restrictions for commercial use

J. Paul Getty Institute - The Getty makes available, without charge, all available digital images to which the Getty holds the rights or that are in the public domain to be used for any purpose. No permission is required.

Stock photography:

Free Images.com - search through millions of free stock photo's, art and vector images. 

Other:

Wikimedia Commons -

PS. 

Please note: take extra care when using photographs with recognizable people, and/or famous pieces of art that might be owned by a museum or collector. Some pieces might be additionally protected by Model right. Also, a few exceptional pieces fall under a perpetual copyright, such as the story of Peter Pan, which the writer Mr. Barry forever licensed to Great Ormond Street Hospital.

sources for this post: Macworld, TheArtLeague, Wikipedia