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  1. Steps for a basic search
  2. Not finding enough?
  3. Finding too much?
  4. Searching by time period and place
  5. Searching by number (digital id., reproduction, call numbers)
  6. Don't ignore "Group Record" links and links within records!
  1. Downloading and Linking tips
  2. Frequently asked questions
  3. More Help...

1. Steps for a basic search

In the ALL RECORDS search blank, type words that describe what you are looking for (it doesn't matter if you use upper or lower case letters and most punctuation is ignored)

Sample search in ALL RECORDS search blank

Brief Records Display

brief records display

Preview Images display

Single catalog record display

The catalog record gives information about the item or group. Also:

Sample catalog record

Larger image display

The larger image display, if available, includes links to higher resolution images and, sometimes, alternate versions of the image. For information about downloading images, see Downloading and Linking tips.

Example of a link to a TIFF image

When you're finished viewing a record or image


2. Not Finding Enough?


3. Finding Too Much?


4. Searching by time period and place

Time period

At present, there is no simple, precise way to search for a date or time period.


It is best to try both specific place names and the names of the larger geographic juridictions when searching geographically.


5. Searching by number (digital id., reproduction, call numbers)

You can only search for digital id. numbers, reproduction numbers, call numbers (and, in some collections, copyright numbers and "other" classification numbers) by using:

What are these different numbers?

All of these types of numbers are formulated in different ways in different collections. For instance, in some collections, negative numbers include "leading zeros" (e.g., LC-USF34-007820). If you are in doubt about how the number may be formulated, select the "Searching Numbers" screen, which gives examples of how the numbers are formulated for any given collection.

Searching by Digital Id.

You may start with different information, depending upon whether you got the number by looking at a catalog record or by copying down the number when displaying the image. Some general rules of thumb for searching digital id. numbers are:

If you see in a catalog record:
DIGITAL ID: ([format]) [letters] [numbers][letters].[numbers]
You type: [letters] [number]

You see: (b&w film copy neg.) cph 3c07395
You type: cph 3c07395

If you're starting with a digital file name that ends with: r.jpg, v.jpg, or u.tif
You type: The letter/number string after the final slash, dropping the "r.jpg," "v.jpg," or "u.tif" part.
Note: A known problem with the system is that it sometimes gives an error message when retrieving a single string of numbers. The remedy is to keep trying or to find the letter code after "/pnp/" and include that in your search.

You see:
You type: 3c07395 (or, more reliably, cph 3c07395)

Occasionally, a digital file is part of a set of images that do not have individual catalog records, and you need to retrieve the record for the whole set and then page through the images to locate the item.

If you see: A digital id. with two sets of numbers at the end, separated by a hyphen
You type: The letters and numbers, dropping the set of numbers after the final hyphen

You see: LC-DIG-ppmsca-09666-0002 (digital file from L9-68-3619-N, frame 3A)
You type: LC-DIG-ppmsca-09666

If you see: A digital file name that ends with two sets of numbers, seemingly not numerically related (or you simply try searching the final set of numbers, dropping the letters as instructed above, and get no result)
You type: The second to the last set of numbers (or, more reliably, the second to the last set of numbers, and the letters appearing after "/pnp/")

You see:
You type: 09666 (or ppmsca 09666)


6. Don't ignore "Group Record" links and links within records!

Some group records contain links to images and/or links to further information within them.


Some item records that have very brief information may be fleshed out by selecting the "Find any corresponding online LOT(group) record" link, in order to find out about the group the item comes from. Not all items have a corresponding group record.

Sample link from an item to a group record


7. Downloading and Linking Tips

Downloading Image Files

The Prints & Photographs Online Catalog includes images in the following formats:

A complete description of these formats can be found in a document on the American Memory web site: How to View Prints and Photographs.

In cases where the rights to an image have not been evaluated or are known to be restricted, .jpg and .tif images will not display to those searching outside of the Library of Congress.

We occasionally get reports that individuals have difficulty saving .tif files, even when the link is visible to them. One possible explanation for this is that the file is large (many .tif files exceed 10 megatbytes, and some are as large as 190 megabytes). Particularly when using a dial-up connection, it can take considerable time to open or save such a file. It is best, in these instances, to try to save the file without first opening it. Browsers and helper applications vary in how they present downloading options and steps. The following are the general steps for saving files.

To save images:

  1. Place your mouse over the image of the desired jpeg or tiff link.
  2. Click the right mouse button (PC) or depress and hold the single button of the mouse (Macintosh).
  3. A menu will appear.
  4. A box will appear in which you indicate your desired name of the image file and where you wish it to be saved. Note: Web images often have non-intuitive file names (ex. 1a34653u.tif)-you may want to rename the image to something you will understand later (e.g., railroad.jpg).

Image Resolution

The quality of the digital images varies greatly, depending upon when and from what source the digitizing was done. In general, digital files that are considered of high enough resolution for the Library's Photoduplication Service to make a quality reproduction from it include an "LC-DIG..." type of number in the reproduction number field.

Gauging the "dots per inch" (dpi) of an image file

Images found in the Prints & Photographs Online Catalog vary considerably in resolution. The size of the original or copy that was scanned also varies, making it difficult to state the "dpi" of any given file.

When using an image you have downloaded from the catalog, the "dpi" is partially determined by the size with which you intend to reproduce the image. Most image software enables you to set the desired size and then view the resulting dpi or, conversely, to set the desired dpi and see what size image can be reproduced at that level.

Here's a rough and ready way to estimate what dpi you will get based on the size of the image file: divide the pixel dimensions for the digital image by the dots per inch you wish to achieve--this will tell you what size the image will need to be.


Sample digitized image

Linking to Particular Records

The display of PPOC catalog records is dynamic. That is, the computer assembles the display in response to your particular request. This poses a challenge for linking and bookmarking since the URL (Uniform Resource Locator or Web address) is temporary; if you bookmark one of these temporary record displays, you will not be able to reach the address later. Do not rely on any address with the word “temp” in it. For most PPOC records, you can get a permanent URL by following the steps below:

Find the URL:

Copy the URL:

Adding the page to Bookmarks or Favorites:

With the URL in the Location Box of the browser, you can now bookmark the Web page.

Link the URL:

Paste the tested URL into your Web page/HTML as the link URL.


8. Frequently Asked Questions

Why aren't images displaying?

If a message at the top of the catalog record says "No digital image available," no image will display.

Why don't I find images I know the Prints & Photographs Division holds?

Not all of the holdings of the Prints & Photographs Division are represented by online catalog records. Some popular images cataloged years ago are so far only accessible through manual files in the Prints & Photographs Reading Room. Some images are cataloged in groups, so your image may not have an individual entry. If you have correctly entered various search terms, searching broadly across all collections/categories and in all the text of the records, and still have not found the material you are seeking, you may want to check with us through the Ask a Librarian service. For further information about what is in the catalog, see About the Prints & Photographs Online Catalog and the section of this document entitled Scope of Prints & Photographs Online Catalog.

How do I obtain copies of material found through the catalog?

It is possible to download many images from the online catalog. See Downloading and Linking tips.

Copies of most images listed in PPOC can be ordered from the Library of Congress Photoduplication Service by by email, fax, or mail. Selecting the "How to Obtain Copies of This Item" link near the top of the catalog record will provide you with the information you would need to place an order.
How to Obtain Copies sample

Why am I having problems viewing/downloading this tiff image?

We occasionally get reports that individuals have difficulty viewing or saving tiff files, even when the link is visible to them. There are a few possible explanations for this:

  1. The file is large. It may be that it is simply very slow to load; particularly when using a slower connection, it can take considerable time to open or save TIFF files, some of which exceed 100 mb.

  2. It is a 16 bit file. If it is labeled "Highest Resolution TIFF Image," it is a 16 bit image; many older viewing softwares are not configured to handle 16 bit images. It is best, in these instances, to try to save the file without first opening it (see Downloading and Linking tips).

  3. Some TIFF images display more successfully in one browser software than another (e.g., an image may display in Firefox that does not display in Internet Explorer). The symptom of this problem is often that, once the TIFF image loads, you just get a series of strange text charaters. Try another browser. (You are also welcome to report the problem via our Ask a Librarian service, and we'll request to have the image adjusted for use in all browsers.) [view Ask a Librarian form - please include the REPRODUCTION NUMBER or DIGITAL ID]

  4. You have Quicktime software that is trying to display the TIFF image. If after waiting for a TIFF file to load, you get what looks like a piece of torn movie film, you have encountered Quicktime unsuccessfully attempting to display the TIFF file. Quicktime tries to read TIFF files, but it can't read all varieties of TIFF files, including some found on the Library of Congress web site. You will need to instruct Quicktime to stop trying to display TIFF files. Once you've done this, your TIFF software, if you have one installed, should start working. Here is how to disable Quicktime for the purpose of viewing TIFF files with a different software tool:

    1. Play a Quicktime Movie with the Quicktime Player. A short one is available here: <>.
    2. At the right end of the navigation bar (below the movie window) click on the small down arrow. Click on "About Quicktime Plug-In" and make sure you have version 5 or higher. (If not go to <> before proceeding with the rest of the steps and download and install the latest version, then return to these instructions and begin again at step one.)
    3. Click "OK," then click on the down arrow again
    4. Select Plug-In Settings
    5. Select MIME Settings
    6. Double click the TIFF entries until the plus-signs there go away.
    7. Now try the TIFF file again. It should work with the TIFF software on your computer, if the TIFF file format is properly "associated" with your web browser. (For a list of TIFF viewers, see: )

What size is the original image?

If the size of the original image has been recorded in the online record, it will be found in the MEDIUM field.
Example of size information given in MEDIUM field

Many online catalog records do not include the measurements of the original item, because of the resources it takes to record this information and the uncertainties that can occur in measuring images of various types.

In some cases, a general size range can be gleaned from a filing designation given in the CALL NUMBER field. Letter designations that appear at the end of many Prints & Photographs Division call numbers for individual prints, photographs, and drawings (posters are an exception) indicate the size of the container in which the item is housed.

Sample call numbers that include container designations:
ADE 11 - Marie, no. 2 (C size)
PGA - Schulz, F.G.--Stuttgarter Bilderbogen (B size)
FP - XX - S354, no. 3 (D size)

NOTE: The size of the container only offers a general approximation of the size of items contained within the container. The size of items in the container can sometimes be substantially smaller than the dimensions of the container itself.

Container Designation Type of Container Size of Largest Mat, Folder, Sleeve or Item the Container Holds
AA box 11 x 14 inches or smaller
A box 11 x 14 to 14 x 18 inches
B box 14 x 18 to 20 x 24 inches
C (except posters) box 20 x 24 to 22 x 28 inches
D (except posters) map case drawer 22 x 28 to 28 x 40 inches
E (except posters) map case drawer 28 x 40 to 36 x 48 inches
F map case drawer 36 x 48 to 45.5 x 74.5 inches
Ff "other" map case drawer up to 40 x 60 inches

How do I get permission to use an image found through the catalog?

The Library of Congress can neither grant nor deny permission to use images, as it does not own the rights to most images in its holdings. The Prints & Photographs Division attempts to provide known information about the rights to images. Whether or not you can use an image is partly determined by what you intend to do with it, however, and rights to many images found in the Prints & Photographs Online Catalog have not been individually evaluated.

Finding Out About Image Rights

There are several online sources of information that may indicate the rights status of an image. Check:

If none of these sources indicate the rights status of an image, consult reference staff to see if any further information is available (our Ask a Librarian service is available for users who are researching from off-site).

9. More Help

Searching Concepts and Tips

The Prints & Photographs Online Catalog gives you the option of searching all online records at once or confining your search to a particular collection or category.

Once you select the pool of records to search, there are three ways to search the records: text search, search particular parts of the catalog record, and choose from lists of terms used in catalog records.

Search Tips:

Scope Of Prints & Photographs Online Catalog

The Prints and Photographs Online Catalog provides access to a rich cross-section of the Prints & Photographs Division's holdings and is growing daily, but not all of the holdings are individually represented in the online catalog. The catalog includes:


How the Prints & Photographs Online Catalog Relates To Other LC Search Systems


Skip Navigation LinksThe Library of Congress >> Prints & Photographs Division >> Prints & Photographs Online Catalog>> Help

June 4, 2008