Where To Find Public Domain Images (Resources)  

The internet is home to several sites each hosting thousands of stock photos or public domain images.  Some sites require registration while others are freely accessible to anyone. The quality of the images varies from scanned blurry historical images to large high resolution digital photos.  Here are the major ones

Wikimedia Commons

http://commons.wikimedia.org/wiki/Main_Page
This has to be the largest multimedia repository under the Wikipedia project where anyone is free to download and use any of its photos, audio, videos, and other media content. The site boasts of more than 10.5 million media files it calls “reusable media:” which are mostly owned and contributed by their original creators.  In general, they are freely reusable without the need for permission but some may require that the creator be acknowledged. Most images are among the finest in the internet with 2k high resolution averaging 700 kb files sizes in JPG. You can browse through the photos by author, location, topic, type and license (Creative Commons License, Public Domain or GFDL)

Public Domain Photos

http://www.public-domain-photos.com/
The site banners 5,000 copyright-free photos and 8,000 free cliparts that anyone can download freely for both personal and commercial use.  True to its claim, the site has two main tab sections for photos and cliparts with virtually identical A-Z categories, from animals, buildings, flowers, to vehicles.  Many of the photos come in high resolution 2k sizes with typical 700kb file size in JPG format while most are in the 800 x 600 resolution with a 72kb file size in JPG.  There are no fancy downloads buttons.  The photo of your choice is displayed in full resolution which you can just right-click to download straight to your hard drive.

Stock Exchange

http://www.sxc.hu/
With a catchy abbreviated name like stock.xchng, the site is considered one of the best resources to find royalty-free stock images.  Todate, the site houses nearly 400,000 online photos and growing.   You only need to register without charge to access and download the photos.  While these images are freely downloadable, they are licensed to Stock Exchange, and restrictions still apply especially if you use the images for commercial and profitable publication.  You can get high resolution 2k images at 2.3M file sizes in JPG format which you can download by right clicking to save on you PC.

The Commons on Flickr

http://flickr.com/commons
One of the most popular photo sharing sites, Flickr features a collection of photos in the public domain contributed by various organizations from private institutions and the government.  These include NASA, various universities, the Library of Congress, Powerhouse Museum, Brooklyn Museum, and Smithsonian Institution, including several individuals and groups that share images with no known copyright restrictions.  You can search the site for a specific topic or you can go direct to the contributors to see their archives. Users are also invited to describe images or leave comments for some photos.

PD Photo

http://pdphoto.org/
A personal site owned by a programmer/photographer Jon Sullivan based in San Diego, California, PD Photo houses a sizable collection of free public domain pictures in the thousands and growing. Because the site owner is apparently an avid traveler, the site has one of the most extensive collections of travel photos from around the US.

Google Life Photo

http://images.google.com/hosted/life
The leading search engine provider features millions of public domain photos from Life magazine’s photo archive.  The site categorizes pictures in 12 discrete decades from the 1860s to the 1970s and is also cross-categorized into People, Place, Events, Sports and Culture. Most of the photos are in black and white in high resolution JPG format.

US Library of Congress, Prints & Photographs Online Catalog (PPOC)

http://www.loc.gov/pictures/
The US Library of Congress is home to one of the richest sources of information in the world.  Its archive of digital images representing the various sections of the Library includes photos, drawing, posters, prints, engineering and architectural blueprints that have both local and international scope. The photo archives represent a visual documentation of the history, culture, lifestyle, achievements and interest of the American people.

everystockphoto

http://www.everystockphoto.com/
The site is a search engine focused on free photos in the public domain now numbering more than 11 million as featured in various websites and indexed in the search engine. The site does not have a category of photos but takes stock of the most popular searches and get categorized as popular and featured searches.

 U.S. Government Graphics and Photos

http://www.firstgov.gov/Topics/Graphics.shtml
This can be considered a photo search engine that has access to thousands of free public domain and copyrighted images archived in various U.S. government sites such as the branches of government, military arms (Air Force, Navy, etc), NASA,  tourism and wildlife bureaus, historical commissions, libraries and museums, technology and sciences, energy, agricultural bureaus and cultural agencies, etc.  You can make quick searches narrowed down by topics and government agencies.  The site itself does not hold any photo archive but any search will bring you to the appropriate photo page in a relevant government agency.

MorgueFile

http://www.morguefile.com/
Bannered as the “public image archive for creative by creatives”  the site offers thousands of high resolution digital stock photos that attach no agreement or restriction to download.  You also need not register to access its archive.  The site owns these public domain images and offers free licenses that demand no attribution.  You can also adapt or modify these images and use it for commercial purposes provided you do not sell the license or sublicense or claim ownership in their original state. 

Liam's pictures from Old Books

http://www.fromoldbooks.org/
This is another personal website from an antique book collector Liam Quin who has archived more than 3,100 high resolution pictures and drawings scanned from more than 180 antique and rare books in his personal collection.  There are no more copyrights in these digitized images that are considered in the public domain.  You only need to let him know if you plan to use any of his images as a courtesy. 

WorldImages

http://worldart.sjsu.edu
Operated by the California State University, the site contains more than 80,000 images licensed under the Creative Commons Attribution –Noncommercial license.  They are free to download and use for non-profit and educational purposes.  The free download doesn’t transfer ownership of the images and the site asks users to acknowledge copyright owners.   You can use its on-site search engine with advance search features or go browse by collection and portfolio grouping.

There is a lot of material in the public domain.  For instance, The Library of Congress holds 13 million prints and photographs as well as 200,000 film titles. In addition, there are hundreds of thousands of drawings, maps, posters and other media available.  The National Archives has eight million photographs and 150,000 reels of film, 160,000 sound recordings and more than 20,000 video tapes.   Much of this material is public domain, and this is only what is available at two places!

Because of the sheer volume of material available, no one list of all of it exists, and if it did, it would be too big to print!  Luckily, there are manageable lists and catalogs of  parts of these collections, usually organized by subject. 

http://en.wikipedia.org/wiki/Public_domain_image_resources
http://www.publicdomainsherpa.com/public-domain-photographs.html

http://en.wikipedia.org/wiki/Wikipedia:Public_domain_resources