Why Images?
As JSTOR's Mission & Goals suggest, we strive
to meet many objectives and to satisfy the needs of all participants. The
original concept for JSTOR was to convert the back issues of paper journals
into electronic formats that would allow for savings in space (and in capital
costs associated with that space) while simultaneously improving access to
the journal content. Thus, it is equally as important for JSTOR to be providing
faithful replications of the original print journals as it is for it to be
providing access to the archive, since the electronic version is to be used
as a substitute for the print version.
One important technological decision that JSTOR made was to deliver the content
of the archive as images. We decided to combine the advantages of page images
with a searchable text index, and JSTOR stores the data in both forms. JSTOR
delivers scanned page images to its users, while using the raw text files
(created using Optical Character Recognition (OCR) software) behind the images
for search purposes.
Benefits of Images:
- Faithful Replication: If, in keeping with our mission
to function as a trusted archive, JSTOR is to serve as a substitute for
the journal volumes on the shelves, it must offer an electronic version
that is a faithful replication of the original. An image-based approach
ensures the integrity of the materials in the archive, while also retaining
the appearance and "look and feel" of the journal in its original
presentation. This is central to our mission and a key basis upon which
JSTOR was founded.
- Representation of Non-Text Content: Whether they appear
as photographs, charts, tables, or special characters and formulae, certain
components of articles generally cannot be displayed with 100% accuracy
using text-based methods available to standard web browsers.
- Accuracy of Images: Page images are 100% accurate. JSTOR
creates a text index for search purposes as part of its production process
through the use of OCR software. Our scanning vendor conducted a series
of reviews of OCR samples on a variety of materials and found a 97% average
accuracy rate (on uncorrected text). In JSTOR, some journals will have OCR
accuracy rates as high as 99.95%. But, although our OCR is accurate for
search purposes, it is unacceptable for display, owing to typographical,
word order, formatting, and other elements that are not accurately represented.
The appearance of typographical and other errors could undermine the perception
of quality that publishers have worked long and hard to establish and that
users of all kinds expect. Indeed, while users in the visually impaired
and learning disabled communities might prefer text, displaying our OCR
would not offer a product and experience that is equivalent to what users
in the non-visually impaired and non-learning disabled communities encounter.
Appropriate assistive technology designed specifically for the visually
impaired and learning disabled communities can offer far better accuracy
than JSTOR can were we to display the OCR’d text we have created for
search purposes.
The importance to libraries and publishers, as well as to the fulfillment
of our not-for-profit mission, of faithful replications of journals, the ability
to display non-textual material accurately, and the problems associated with
displaying the OCR text we have created for search purposes are the primary
motivations for JSTOR's use of images as the mechanism for delivery of journal
articles.
We are aware that our image based approach causes certain difficulties for
users who are visually impaired or learning disabled and use assistive technologies
to access material on the Internet. JSTOR now offers options to help alleviate
some of these difficulties. For more information, please see JSTOR
and Accessibility.
Last updated July 15, 2003.
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