Open-i Biomedical Image Search Engine- Open-i
Q: What is Open-i?
A: Open-i service of the National Library of Medicine enables search and retrieval of abstracts and images (including charts, graphs, clinical images, etc.) from the open source literature, and biomedical image collections. Searching may be done using text queries as well as query images. Open-i provides access to over 3.7 million images from about 1.2 million PubMed Central® articles; 7,470 chest x-rays with 3,955 radiology reports; 67,517 images from NLM History of Medicine collection; and 2,064 orthopedic illustrations.

Longer descriptions are available in a research article "Design and Development of a Multimodal Biomedical Information Retrieval System" ( ) and a technical report ( )

Q: Are the images in Open-i collection in public domain? May I use a particular image for my project?
A: Open-i images are from one of the following sources:

Reuse of Open-i images is determined by the license type of the image. A link to the applicable license type, if available, may be found below the individual Open-i image on the detailed view page.

Please refer to the following web page for information on the PMC open access subset and the PMC Copyright Notice:

If copyright restrictions for an image in the PubMed Central collection are not specified or are unclear, please contact directly the journal directly that published the image.

To navigate to the full version of the paper at the journal publisher site, please follow the link to PubMed® located below the title. When viewing the abstract in PubMed, use the links to the full text in the upper right corner to get to the journal that published the paper containing the image. If a link to HTML is available below the title, it will bring you to the journal directly.

Images from the Indiana University hospital network are distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License ( ).

Images from the Orthopaedic Surgical Anatomy Teaching Collection at the USC Digital Library have the following Rights statement:
Distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License ( that permits unrestricted use, distribution and reproduction in any medium, provided the work is attributed to Irving Rehman, Ph.D., F.I.C.S., and Chadwick F. Smith, M.D., Ph.D., F.A.C.S., F.I.C.S., and source in the manner specified by the publisher.

Please refer to the following web page for copyright information for Images from the History of Medicine:

Q: How do I use an image as query?
A: There are two ways to search using images:

  1. Drag and drop the image file onto the Open-i search or results page to initiate an image search. Supported file types are .jpeg, .jpg, .gif and .png.
  2. Upload an image file using the “Query by Image” link in the upper right corner.

Q: What is the difference between the Citation List view and Image Grid?
A: The citation list view shows the best match image on the left along with citation information on the right. The grid view displays all matching images from an article. You may switch between views by clicking on the appropriate icon next to “View as” area to the right of the search box.

Q: How do I rank my results by date?
A: Open the Rank By section in the “Limits” bar. Click on Newest or Oldest. This only gives more weight to the date; it does not sort by date.

Q: How do I use limits?
A: By default, the “exclude graphics” limit is applied to the search, which excludes charts, graphs, drawings, etc. All subsets and specialties are searched. Text is searched in all fields. Results are ranked in relevance order. To filter the results, you may select one or more categories in the “Limits” bar. To view or remove selected filters, use the “Selected Limits” area above the “limits” bar.

Q: How do I open “View Article” results in a new window?
A: Control-Click on the link to open and view the article in a new browser window.

Q: How do I open “View Similar Images In” results in a new window?
A: Control-Click on the link to open and view the results in a new browser window.

Q: When my browser window is narrow I lose the View Similar Images and View Article links in list view?
A: When the window is narrow, Open-i responsive design puts the user in mobile mode. Click, tap, or swipe the three vertical dots to view those links.

Q: In Chrome, my video doesn't play somtimes, what do I do?
A: We have a known issue for some videos in Chrome. Please do a Ctrl-Shift-R to refresh the page and the video will play.

Q: Can I do an exact search? I am looking for AID and don't want to see papers about HIV/AIDS.
A: By default, the search terms are expanded with UMLS synonymy and the singular/plural forms, so aid is expanded to HIV/AIDS.
To avoid expansion, use NO_EXPAND (all upper case) + search term, e.g., NO_EXPAND AID If you want singular/plural expansion, but not UMLS synonymy, use TERM_EXPAND + search terms. For example, NO_EXPAND heart attack finds 89 articles; TERM_EXPAND heart attack finds 118, and searching for heart attack with default setting results in 2805 articles.