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Rare Materials Reproduction

Northwestern University Libraries maintain and provide access to extensive research collections, including rare and unique materials that may be reproduced upon request according to the following procedures. On this page, you'll find procedures for reproducing non-circulating items from the following collections: 

Submit your request using our online request form.

Requests are considered on a case-by-case basis according to the library policies set forth on this page, donor arrangements, physical condition of the original material, production capabilities and the requester’s agreement to specified terms of use.

We attempt to fill requests five to ten business days following receipt of payment, although certain requests may require significantly longer. Requests are answered in the order they are received. If you have any questions regarding your request, contact the holding library directly at the emails linked above.

Copying fees are determined by curators according to the following pricing schedule. In some circumstances, there will be no charge to members of the Northwestern community engaged in University business (including teaching and research). Individual requests may be denied and fees may be adjusted on a case-by-case basis. Requests for large quantities of material may incur additional fees and may require special arrangements. 

For other formats not listed here, please contact relevant collection staff. 

Original Format Reproduction Form* Fee
Publication-quality scans (600 dpi) from an original under 12"x17" Digital file (TIFF), electronic delivery only (no CD or DVD); 300-600 ppi, 24-bit color $10 per image
Reference-quality scans (300 dpi) from an original under 12"x17" Digital file (JPEG), electronic delivery only (no CD or DVD); 24-bit color $1 per image (number of scans may be limited at curator's discretion)

Northwestern University Library uses a variety of digitization equipment to fulfill requests. Unless different specifications are requested, the following file formats and standards will be used.

Material type Spatial resolution and bit depth File format
Unbound text or image Equivalent of 600 pixels per inch (ppi) or 5400 pixels in long dimension, whichever is higher. TIF
Bound text or image Resolution varies; typically 250-400ppi equivalent JPEG or PDF

Spatial resolution

Spatial resolution describes the fineness of a scan, usually expressed in terms of the number of pixels used to represent an inch on the original (pixels per inch, or ppi). Although the terms are NOT equivalent, occasionally "dpi" (dots per inch) will be used instead of the more technically correct ppi. At the equivalent of 600ppi, an 8.5" x 11" document will yield a scan of 5100 pixels (8.5 inches * 600 ppi = 5100 pixels) by 6600 pixels . At the equivalent of 600ppi, a 12" x 17" document will yield a scan of 7200 pixels by 10200 pixels. 600ppi has been chosen as a generally acceptable resolution that will be equally capable of representing fine lines and small text, and can be used to produce an acceptable facsimile of the original.

However, when scanning reduced-size materials, such as slides, film or microformats such as microfilm or microfiche, a slightly different method of computing resolution is needed. As indicated in the chart of fees, 5400 pixels in the long dimension (the longest side) is the smallest overall dimension used for scanning Northwestern University Library materials. However, a 600ppi scanning resolution is not sufficient for reduced-size originals. For example, a 35mm slide typically measures 1" x 1.5". To achieve a scan measuring 5400 pixels in the long dimension, a much higher scanning resolution of 3600ppi must be applied (5400 pixels divided by 1.5 inches = 3600 pixels per inch).

Bit depth

Bit depths are named according to the amount of computer storage space allotted to store the color information for each pixel. These numbers are powers of two. Two is used because computer information is binary; one "bit" is can hold one of two binary values: either 0 or 1.

Different color depths use different ways of encoding information. 8-bit color images usually use a custom palette of 256 colors. Numerical values in the computer's memory refer to particular colors in the palette. The palette acts as an index where colors can be looked up. 16-bit and 24-bit images don't use a palette; they store the red, green, and blue components of each pixel directly in the computer's memory.

  • 1-bit: black & white (21)
    A single bit has value 1 or 0. It stores either black or white. Often used for text. This bit depth is also called "bitonal" or "binary".
  • 4-bit:16 colors (24 : 2x2x2x2=16)
  • 8-bit: 256 colors (28: 2x2x2x2x2x2x2x2=256)
    An 8-bit image has a fixed palette of 256 shades of gray or 256 different colors.
  • 16-bit: Thousands of colors (216)
    A 16-bit image contains up to 32,768 different colors.
  • 24-bit (224) and 32-bit (232): Millions of colors
    Both 24-bit and 32-bit images provide about 16.7 million available colors, more than the eye can actually see. Many computer monitors can support this many colors. Only the first 24 bits are used to determine color. In a 32-bit image, the last eight bits are reserved for information other than color (like transparency and overlays). 24 is the default bit depth used to digitize color Northwestern library materials.

File formats

  • TIF is the default file format for Northwestern library materials. TIF or TIFF (Tagged Image File Format) is an "interchange" standard (supported on many platforms) with many uses. TIF is used in many desktop publishing applications, and is the standard import/storage format for many Optical Character Recognition (OCR) applications. TIF files may be uncompressed, in which case they tend to be very large, or compressed, usually with the loss-less LZW compression.
  • JPEG is the second most common file format used to deliver Northwestern library materials. JPEG (Joint Photographic Experts Group) is both a file format and a type of compression, so be sure you understand the context in which the name is used. A JPEG image can contain millions of colors and is usually the best choice for images with a lot of color variation, such as a photograph. JPEG (or JPG or JFIF) files are also the most common image format for web pages.
  • PDF (Portable Document Format) may be used to deliver multiple page documents. A standard developed by Adobe, it can contain both text or image materials at a variety of levels of resolution. 
  • DV25 is a digital video format with support for audio. It can be stored in one of two wrappers, .mov or .avi, depending on your needs. It is a standard definition compression scheme and can be used as an access master from which to make smaller derivatives for streaming. This type of file averages 12GB per hour.

Calculating file size

This simple formula can be used to estimate the size of an uncompressed digital image file:

  • (Pixel width * pixel height * bit depth) / 8 = file size in bytes, or
  • ((Width in inches * height in inches) * (resolution squared) * bit depth / 8) = file size in bytes

General policies are listed below. Additional information regarding the cost of reproductions, turnaround times, and specific procedures is available from each specific Collection.

Use of personal photography or digitization equipment

Collection curators must approve requests from researchers who wish to bring digital cameras or other photographic equipment into the library. Researchers performing their own digitization will be required to sign a Researchers Copyright Agreement form. 

Copyright statement

The Northwestern University Library provides access to its holdings for educational, personal, and non-commercial use. Materials held by Northwestern University Library may be protected by United States Copyright Law and/or by the copyright laws of other countries. Copyright law protects unpublished as well as published materials. At its discretion, the Library may make limited copies of materials that are still within their term of copyright, provided the copies become the property of the user and no further use or distribution is made without permission from the copyright holder.

Written permission from the copyright holders and/or other rights holders is required for publication, distribution, reproduction or other use of protected items beyond that allowed by fair use. Publication includes, but is not limited to, print, film, slide presentation, video, television, and electronic transmission, including transmission via posting on a web site.

To use either published or unpublished materials from our collections in a publication, requesters must determine whether the work has passed into the public domain and is no longer under copyright protection, or find the copyright holder and obtain permission to reproduce the material. The Library will neither facilitate nor execute these requests, nor will it provide publication permission for materials whose term of copyright has expired. 


Users of materials held by the Northwestern University Library are responsible for securing permission from copyright owners and payment of such additional fees as the owners may require. Users assume all responsibility for questions of copyright or other rights that may arise in copying and in the use made of the copy.

The user assumes all responsibility for infringement of copyright or other rights and agrees that Northwestern University Library is free from liability for any infringement of use by the requester. Northwestern University Library reserves the right to refuse permission and reproductions to anyone who does not agree to these conditions.

Credit line

Cite the appropriate individual library department as follows:

  • "Courtesy Melville J. Herskovits Library of African Studies, Northwestern University Libraries"
  • "Courtesy Northwestern University Art Library"
  • "Courtesy Northwestern University Music Library"
  • "Courtesy Charles Deering McCormick Library of Special Collections, Northwestern University Libraries"
  • "Courtesy Northwestern University Transportation Library"
  • "Courtesy Northwestern University Archives"