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Cornelius Van Vorst, ca.1620; 
Jersey City Free Public Library; Grover Cleveland Political Cartoon; 
Grover Cleveland Birthplace Historical Site Collection Peter Lee, former slave, ca.1880; 
Hoboken Historical Photographs Collection; Farm Map of Hillsboro, Somerset County, 1860; 
Historical Maps of New Jersey Collection; Bathing Beauties, 1890-1930; 
American Labor Museum/Botto House National Landmark Collection; Flag Salute, 1950; 
Seabrook Farms Collection;
NJDH Digital Imaging Specifications
In order to standardize imaging specifications through the NJDH and other archival imaging projects, several standards and requirements have been established. Member sites should adhere to such standards to ensure that digital documents can be uniformly ingested and archived.

Archived Digital Images
Color photos and documents:
  • Should be scanned at minimum 600 dpi for archival purposes.
  • Color space should be sRGB, at least 24 bit truecolor. 8 bits per channel is preferred.
  • Archival files should be in TIFF format, encoded with no compression or (where available) a lossless compression algorithm.

Black and white documents with gray tones, or black and white photos:

  • Should be scanned at a minimum of 600 dpi.
  • Color space should be grayscale. RGB is acceptable, but contributes nothing to pure grayscale images and only increases file size.
  • Archival files should be in TIFF format, encoded with no compression or (where available) a lossless compression algorithm.

Black and white documents with pure text:

  • Should be scanned at a minimum of 400 dpi.
  • Color space should be 2 bit color (black and white), but should be converted to grayscale if the documents are to be digitally resized.
  • TIFF format for archived images.

Additional Considerations - the 3,000-pixel rule

  • Scanning at resolutions much higher than 600dpi may be required if the document is small in physical size.
  • All digitized documents should be scanned such that at least one dimension of the visible area of the document (width or height) is comprised of a minimum of 3,000 pixels each. If a scan at 600 dpi does not meet this minimum, then the resolution should be increased and the document re-scanned accordingly. It is not acceptable under any circumstances to artificially increase the dpi by resampling the image. The original scan must meet the 3,000 pixel minimum.
  • Extraneous image information (such as a calibration strip, record labels, or any part of the scanned image that does not directly pertain to the document itself) should not be included in this calculation. Measurements should be made using only the visible area of the document.
  • Example: a 3"x4" color photograph scanned at 600 dpi will render an image that is 1800 x 2400 pixels. As the width does not meet the minimum, a 600dpi scan will be unacceptable. The scan should be increased to 800 dpi to render a 2400 x 3200 pixel image, and thus bring the image to an acceptable level of detail.
    On the other hand, an 8.5"x11" sheet of paper with black and white text will scan acceptably at 400dpi, rendering a 3400 x 4400 pixel image.
Web Presentation Images
  • Separate web images should be created from the archival images for access by users. These web images, while lower in image quality, will be presentable on a user's screen and can be quickly downloaded. Resolution of web images will be reduced to screen resolution, usually 72-150 dpi, or will be at the same resolution as the master image but accompanied by a “page-turner” interface that allows a user to zoom in and out of the document as needed.
  • Such page-turner formats can also be used for multiple-page documents, such as Adobe Acrobat, MrSid, or djvu. Links to any necessary plug-ins should be offered on the same page as the displayed documents so that users may easily download them.
  • Alternately, jpg format can be used to display individual images. If the digital document has multiple pages and jpg format is used, an interface will need to be created that allows the user to “turn” the pages of the document, displaying the next or previous page of the document as the user requests it. GIF format can also be used for icons and smaller images, but the color space of each image will be dropped to 8 bits (256 colors maximum).
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