San Fernando Valley History Digital Library
California State University, Northridge
Oviatt Library

SFValley Collections Scanning Standards

VIEW STANDARDS SUMMARY (PDF)

GOALS:
  • Objects will be scanned and archival images will be preserved in TIFF format at the same resolution.
  • The presentation images used in the San Fernando Valley History Digital Library database will be created by compressing copies of the archival TIFFs, and saving in JPEG format. The JPEG standard has been chosen for its portability and because it can easily be resized as a "thumbnail" image without significant loss of quality.
  • The presentation JPEG images should retain enough detail to support significant research. Image quality is, however, somewhat reduced by compression and limited by the resolution capabilities of a user's monitor, so standards have been created to accomodate the following considerations:

    1. Resolution of presentation images should allow relevant text to be legible.
    2. If size or complexity requires that an object be scanned in several parts, the separate images should retain a logical coherence.
    3. The file size of the JPEGs and supplementary images should be small enough so that users with telephonic modem connections can access them.
    4. The display size of the JPEG images should be small enough that the users can view them with a minimum of scrolling.

Archived TIFF images scanned between January 2001 and June 19, 2001 were scanned according to the CDL standards: photographs and graphic images at 300 dpi and text at 600 dpi without corrections. However, as new items were included in the project, the scanning guidelines were modified to compensate for the size of the original image, to ensure that detail of smaller images would be viewable in the online JPEG versions. Those specifications marked *CDL indicate derivation from the California Digital Library Digital Image Format Standards.

TIFF IMAGES (archived)
TIFF images are to be created as follows:

  • Original photographs and graphic images larger than 5 x 7 in. will be scanned at 300 dpi and saved as TIFF files with no corrections (*CDL).
  • Original photographs and graphic images 5 x 7 in. or smaller will be scanned at 600 dpi and saved as TIFF files with no corrections (*CDL)
  • Original text-items will be scanned at 600 dpi and saved as TIFF files, with no corrections. (*CDL) (EXCEPTION: If the smallest type on the page is 24 pixels in size or larger, scan at 300 dpi (for example, posters with large type).
  • 35mm slides and negatives will be scanned at 2400 dpi, and saved as TIFF files with no corrections. (How do I do this?)
  • Digital photographs (created using a digital camera) will be saved at their original dpi and saved as TIFF files with no corrections.
  • Color: Black and white photographs and text (black text on white background, not including discoloration due to aging) are scanned in grayscale. Photographs that are monochromatic but are not black and white (i.e., sepia) are scanned in color. Text items with colored lettering and/or colored background are scanned in color.
  • What if the originals are too big for the scanner? If the dimensions of the original item prevent it from being scanned all at once, it will be scanned in two parts, then integrated into one archival TIFF file.

JPEG IMAGES (used in online database)
JPEG images are to be created as follows:

Non-text items
  • If the original graphic or photographic image is larger than 5 x 7 in. (7 x 5 in.), the JPEG should be saved at 100 dpi, with a maximum width of 800 pixels. (*CDL) (How do I do this?)
  • If the original graphic or photographic image is 5 x 7 in. (7 x 5 in.) or smaller, the JPEG should be saved at 300 dpi, with a maximum width of 800 pixels. (How do I do this?)
  • 35mm slides and negatives should be saved at 450 dpi. (How do I do this?)
  • After reducing the dpi and resizing, JPEG images may be corrected for contrast and color, if necessary, to enhance detail. However, an effort should be made to ensure that the JPEG resembles the original TIFF as closely as possible.
  • TIFFs from Digital photographs (created using a digital camera) should be saved at 100 dpi, with a maximum width of 800 pixels.

Text items
  • JPEG images of text documents should be saved at 300 dpi, with maximum dimensions of 800 x 1200 pixels. (How do I do this?)
  • If the text of the resulting JPEG is unreadable (as in a map, for example), detailed view will be created from the TIFF, stored on the server, and linked from the metatdata record.

Detailed Views
  • If an item is too large to provide a sufficiently detailed view within the ContentDM record, and the object cannot be presented in several coherent parts, a supplementary optimized GIF image will be created and placed on the server, and a link to it will be added to the metadata record in the "Larger View" or "Detailed View" field.
  • GIF format has been chosen because this is the preferred format for optimizing of text-images and line art.
  • Here's the procedure.

Links checked June 10 2004

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10 June 2004   © California State University, Northridge 2004