- You can use either capital or lowercase letters. Case does not affect the results of your search.
- You can enter words in any order.
- Some punctuation and special characters (for example, letters with diacritcs) throw off the search. If you get zero results, try re-entering the search without those characters.
- Use the "Search all" blank on the home page to search everything in the catalog at once rather than searching a single collection
- Use fewer words (many "inventory level" records include only information from a caption or caption card, so, for instance, an individual's first name may not be included or fully spelled out)
- Check spelling and spacing of search word(s): Are there alternate spellings? Could two words have been combined into one (or vice versa) in image captions? Have you used abbreviations that can be spelled out?
- Try using wildcards to enable the search to include variations on a word (E.g., child* retrieves child, children, childlike)
- Try selecting from lists of terms in the "Browse By" offerings at the left of the search screen.
- Try "View all" records or images to see if this gives clues about the kinds of images that are in a collection or the kinds of words that are in the descriptions.
- Look through the list of collections with descriptions. Is the image you are looking for something we are likely to have? (E.g., art reproductions, photos of very recent news events, and illustrations of ancient peoples are not strengths of our collections.) For information about what the catalog includes, see "About the Prints & Photographs Online Catalog"
- In the Advanced search, select to "match all words" or to "match exact phrase." Select "No variants" to eliminate words with alternate endings.
- Look through the list of collections with descriptions. Is the image you are looking for something we are likely to have? (E.g., art reproductions, recent news photos, and illustrations of ancient peoples are not strengths of our collections.)
- Try selecting from lists of terms in the "Browse By" offerings at the left of the search screen. Note: Selecting a heading retrieves only records with that exact heading, not records that contain words from the heading. Example: If you select the subject heading "Wales" from a browse list, the system will retrieve records that contain the subject heading "Wales" but not those that have the subject heading "Wales--Rhyl."
- Try searching the Thesaurus for Graphic Materials to see what standardized terms we use to index images you might be interested in.
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At present, there is no simple, precise way to search for a date or time period.
- You can search
for a year or a span of years. But the appearance
of the date or the particular string of numbers
anywhere in the record will cause the record to be retrieved, so you may get records for items whose
artist was born in that year, or records that
include a four digit address.
Note: Catalog records often use estimated dates or multiple dates that are expressed as a range of years. If your year falls within that range, it will not be retrieved. Try neighboring years that end in 5 or 0, e.g., 1750, 1755
- Subject headings often include a chronological component that is expressed in decades. For instance, if the item was produced or depicts something in 1844, the subject subdivision will be 1840-1850. So you might try searching for decades that would be relevant.
It is best to try both specific place names and the names of the larger geographic juridictions when searching geographically.
- Some catalog records include a hierarchy of the places represented by an image or set of images, going from the larger geographic unit to the smaller. Example: Canada--British Columbia--Columbia Mountains.
- In other cases, only the specific place is mentioned, sometimes with an abbreviation for the larger geographic jurisdiction. Example: Los Angeles (Calif.)
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What are these different numbers?
- Call numbers: A string of letters and numbers used to locate the original material filed at the Library of Congress. Example: POS - WPA - ILL .B46, no. 7 (B size)
- Reproduction numbers: An alpha-numeric code that identifies existing black-and-white and color negatives, slides, or transparencies or high quality digital scans from which prints, transparencies, and other reproductions can be ordered. Example: LC-USZC4-1587
- Digital ID numbers: An alpha-numeric code that is the unique identifier for a digital image displaying in the catalog. Example: cph 3b53089
All of these types of numbers are formulated in different ways in different collections. For instance, in some collections, negative numbers include "leading zeros" that must be included in order for the record to be found (e.g., LC-USF34-007820).
Searching for a Specific Number
The most precise way to search for a number is to search it as a phrase. You can either:
- search the number with quotes around it: "LC-USF34-007820" or
- select "Advanced" search and use the pull-down menu to "Match exact phrase"
To add further precision to the search, you can designate your search a "Number" search:
- select "Advanced" search and use the pull-down menu to "Search the number fields "
Searching by Digital ID
You may start with different information, depending upon whether you got the number by looking at a description or display page or by copying down the number when displaying the image. Some general rules of thumb for searching digital id. numbers are:
If you see a string that includes the format or a URL beginning with "hdl," type the final letters and numbers
You see: Digital ID: (b&w film copy neg.) cph 3c07395 http://hdl.loc.gov/loc.pnp/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.
Example: You have a file that is called: 3c07395r.jpg. To retrieve it in the catalog, type: 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 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 precisely, the second to the last set of numbers, and the letters appearing after "/pnp/")
You see: http://memory.loc.gov/pnp/pplot/00900/00991/0004v.jpg
You type: 00991 (or pplot 00991)
The Historic American Buildings Survey/Historic American Engineering Record/Historic American Landscapes Survey images are presented in sets (surveys). Rather than searching for an individual image in the survey, you must retrieve the description for the particular survey and then display the images. In the path name for the image, you would search by the letter-number combination that appears before the format designation.
You see: http://memory.loc.gov/pnp/habshaer/nm/nm0000/nm0099/sheet/00002r.tif
You type: nm0099
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Some group records contain links to images and/or links to further information within them.
- HABS/HAER/HALS records contain links to different types of documentation:
Records for groups of images (LOTs or ADE UNITs); all or some of the items may have been cataloged and digitized as people requested reproductions:
Select the "Check for online items from this group" link to the left of the description.
Some groups of images have been digitized but not individually cataloged. Select the icon that indicates that you can click for more images.
FSA/OWI records have links that allow you to see related images that do not have titles and are not indexed by photographer, because they were not captioned or printed at the time the images were produced. Selecting the "Browse neighboring items by call number" to the left of the description to view these untitled images.
Some item records that have very brief information may be fleshed out by selecting the "Check for online group record (may link to related items)" link, in order to find out about the group the item comes from. Not all items have a corresponding group record.
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Downloading Image Files
The Prints & Photographs Online Catalog includes images in the following formats:
- gif - generally small "thumbnails" used
for previewing images; a gif image
displays at the top of its associated catalog
record and, in some cases, it is the only
image that will display to those searching
outside the Library of Congress because of
rights considerations (extension on the file
name is .gif). The resolution is
generally about 150x150 pixels.
- jpeg - generally a larger image that displays in a separate screen from the catalog record; sometimes two types of jpeg files are available--one for reference viewing and one at a higher resolution (extension on the file name is .jpg).
- tiff- generally the highest
resolution file available in PPOC, viewed
or downloaded via a link on the screen where
the reference jpeg displays (extension on
the file name is .tif).
Information on software for viewing tiffs 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 200 megabytes or more). 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:
- Place your mouse over the image of the desired jpeg or tiff link.
- Click the right mouse button (PC) or hold the control key while clicking to get the dialogue box (Macintosh OSX. For earlier versions: depress and hold the single button of the mouse).
- A menu will appear.
- Select Save image as or Save Picture as if you moused over an image.
- Select Save target as or Save link as if you moused over a link.
- 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.tif).
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.
Find out the dimensions of the digital image. One easy way to do this is to right-click on the image, and look at the image properties. When viewing TIFF images, you may need to select a choice such as "About..." in your viewer.
The image properties tells you the scan is 720 x 1024 pixels.
- For a 300 dpi result, divide each pixel
dimension by 300, and you'll know roughly
how large the scan can be printed and be called
720 / 300 = 2
1024 / 300 = 3
As long as the image printed from this particular file is not much beyond 2 x 3 inches, it will be in the 300 dpi ballpark.
Linking to Particular Records
Use the "Share/Save" links at the top. The "Share/Save" feature enables you to link to any individual record, set of search results, or individual page within PPOC.
Other options: copy the URL in your browser's address window and use that as a link.
- if a "handle" (a URL beginning "http://hdl.loc.gov . . .") is displaying with an image, you can use that to link to the image display; it is the permanent address for the digital item.
- to link to the description, use the URL appearing after "Bookmark This Record:" at the bottom of the description
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8. Frequently Asked Questions
- Not all pictures described in the Prints & Photographs Online Catalog are digitized. A "Not digitized" image usually indicates this for descriptions of single items.
- In cases where a rights holder has indicated they do not wish larger images to display outside the Library of Congress or the rights to the image have not been evaluated, only a thumbnail (.gif) image will be available to searchers outside the Library of Congress.
- The list of collections with descriptions and each collection page includes information regarding whether the collection has been digitized and whether larger images will display outside the Library of Congress.
- If the collection description indicates that images should be displaying at your location, you may want to check to see whether graphics have been turned off on your browser. If a "broken" graphic appears, there may be a problem with the link to the image or a temporary server problem.
It is possible to download many images from the online catalog. See Downloading and Linking tips.
Quality copies of most images listed in PPOC can be purchased from Library of Congress Duplication Services. Selecting the "Obtaining Copies" tab when you are displaying an individual record will provide you with the information you will need to place an order.
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:
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.
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).
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]
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:
- Play a Quicktime Movie with the Quicktime Player. A short one is available here: <http://memory.loc.gov/mbrs/edmp/4051.mov>.
- 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 <http://www.apple.com/quicktime/download/> 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.)
- Click "OK," then click on the down arrow again
- Select Plug-In Settings
- Select MIME Settings
- Double click the TIFF entries until the plus-signs there go away.
- 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: http://memory.loc.gov/ammem/help/view.html#photograph )
If the size of the original image has been recorded in the online record, it will be found in the 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
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.
|Type of Container
|Size of Largest Mat, Folder, Sleeve or Item the Container Holds
|11 x 14 inches or smaller
|11 x 14 to 14 x 18 inches
|14 x 18 to 20 x 24 inches
|C (except posters)
|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
|map case drawer
|36 x 48 to 45.5 x 74.5 inches
|map case drawer
|up to 40 x 60 inches
Rights assessment is your responsibility.
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:
the description (generally in the "Rights Advisory" field)
the "Rights and Restrictions Information" page on the Prints & Photographs Reading Room site
- includes specific rights statements for particular artists, corporations, and collections
- features a reference aid, "Copyright and Other Restrictions That Apply to Publication and Other Forms of Distribution of Images," which outlines steps for assessing rights to individual images.
February 17, 2010