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Digital Imaging

Page history last edited by epfotenhauer@wils.wisc.edu 9 years, 1 month ago

Wisconsin Heritage Online's Digital Imaging Guidelines (or Word version) offers detailed information about our recommended standards for scanning, file naming, image editing, and more. Looking for a definition to an unfamiliar term? Check out the WHO Digitization and Scanning Glossary (or Word version).

 

Reformatting

Reformatting means using a scanner or a digital camera to convert an image from analog to digital form. 

 

Scanning

  • WHO Scanning Quick Guide, an extract from the WHO Digital Imaging Guidelines, highlighting scanning processes.
  • "Scanning Specifications for Digital Projects/Preservation," Ohio Historical Society (pdf)
  • "Text and Image Scanning Helpsheets," University of Virginia Library
    • includes guidelines for using OCR (Optical Character Recognition) to create machine-readable text documents
  • "General Guidelines for Digitization" University of Wisconsin Digital Collections Center
  • "Digital Production," Chapter 4, Digitization Guidelines (North Carolina ECHO)
    • See especially the "Scan-Once Methodology": In creating digital images, the digital production should be done at the highest level of quality that an institution can afford. The higher the quality, the longer the life of the image and the more versatile its uses . . . Do not anticipate returning to re-digitize.

 

Digital Photography

 

Quality Control

  • WHO Image Editing Quick Guide, an extract from the WHO Digital Imaging Guidelines which highlights specific recommended editing techniques.
  • Image calibration. Using a calibration target (color and/or grayscale) when you scan an image or take a photograph will allow you to accurately adjust the color balance in Photoshop.
  • Monitor calibration. The purpose of monitor calibration and profiling is to create a situation where the image on your monitor closely matches the image as it will appear on a print, a proof, a press sheet--or, if your work is destined for the web, as viewed on the average uncalibrated PC or Mac monitor. --from UPDIG Photographers Guidelines
    • Monitors can be calibrated using software or hardware. Although the software solution is more affordable, a hardware tool provides more accurate and repeatable results. See the WHO Digital Imaging Guidelines (page 7) for more details and equipment recommendations. 

  • Read more about quality control in BCR's CDP Digital Imaging Best Practices version 2.0, 2008 (pages 29-33) 

 

Object Handling 

 

 

Digital Files

Wisconsin Heritage Online recommends a "use-neutral" approach to creating, processing, and storing files. This means that you will first create a high-quality master file, then reformat that file in different ways for various uses - displayed on a computer monitor or TV screen, printed in a book or newspaper, reproduced for an exhibition, or shared in a yet-to-be-invented digital medium. 

 

Your objective is to create a high quality digital resource that will remain useful in the long term. This resource should have as its cornerstone an archived digital master that can be considered "use-neutral" and can serve as the parent to many children that are used in print, web, video and other forms of reproduction. 

                                                                                                                        -- from NINCH Guide to Good Practice

 

File Formats

  • Digital master (aka archival master): high-quality, high-resolution image with no manipulation; very large file size (approx. 36MB)--use TIFF

  • Service master: high-quality, high-resolution image with manipulation (i.e. cropping, color correction)--TIFF or JPEG2000 preferred but could use JPEG if storage space is at a premium

  • Display image (aka access file or derivative): lower-resolution file with smaller file size, suitable for display on the web--use JPEG 

 

To read more about TIFFs, JPEGs, and file resolution, see "Choosing a File Format for Digital Still Images," JISC Digital Media and "Image Capture" from Introduction to Imaging, Getty Research Institute. 

 

File Naming

Systematic file names should be worked out in advance of any digitization work. WHO recommends the 8.3 convention, which is an eight-character file name and a three-character extension, e.g. aa000001.xxx. To read more, see "Choosing a File Name," (JISC Digital Media).

File names should be:

  • Unique and consistent

  • Alphanumeric

  • Lowercase

  • Free of spaces and tabs

  • Numbered sequentially using leading zeros (e.g. 001, 002, 003; not 1, 2, 3)

 

Image Processing

After scanning or photographing you may wish to do some image enhancement in Photoshop or another imaging program. Adjustments such as rotating, cropping, and color balancing can improve the end user's viewing experience. DO NOT make adjustments to the digital master file. Instead, make the changes on a second file, known as the service master. Recommended guidelines for image processing are available in the WHO Digital Imaging Guidelines (pages 20-24). Or see the WHO Image Editing Quick Guide.

 

Storage

Even if you are taking advantage of WHO's collection hosting services, your organization is still responsible for the long-term maintenance and storage of your digital files. See the wiki's Preservation page to learn more.

 

 

Read more about digital imaging best practices . . . 

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