Introduction to Digital Imaging

 

There are two types of image files that are important to know about.

    • TIFFs are high-quality images with very large files sizes.
    • JPEGs (or JPGs, or JPEG2000) have much smaller file sizes, but they also have lower resolution and quality.

For preservation and duplication purposes, your original images should always be scanned as TIFFs. Their file size is too large to be displayed online, however, so you also need to convert your images to JPEGs at some point.

 

You can either manage this conversion process on your own, or use CONTENTdm's Full Resolution Manager to automate the process. See Full Resolution Manager Tips.

 

Resources

For more detailed information on digital images and reformatting, see:

 

 

Hardware Requirements

  • As a general rule of thumb, purchase the best equipment that is reasonable within the confines of your budget. Older, slower, or less equipped computers can add a lot of time (and frustration!) to digitization projects.

{Note: any organization wishing to use WHO's hosted services are required to have a high-speed internet connection.}

 

    • Purchase a computer dedicated solely to digitization initiatives
    • Purchase as much Random Access Memory (RAM) as your budget allows. More memory allows the computer to more quickly process large amounts of image data.
    • Purchase computers with processors optimized for image manipulation
    • Purchase computers that support high-speed data input through serial connections: USB 2.0 or IEEE 1394 “Firewire”
    • For more information and suggestions about hardware, refer to the WHO Digital Imaging Guidelines

 

 

Software

  • CONTENTdm is the content management system that projects hosted by the Wisconsin Historical Society use. In order to upload your images into WHO, you will need to download and install CONTENTdm's Acquisition Station. See the Quick Start Guide for information on how to do that.
  • Even if you are taking advantage of WHO's hosted services, your organization is still responsible for the long-term maintenance and storage of your images. Check out ACDSee Photo Pro, an affordable ($40) software program that helps manage your digital images. It facilitates batch renaming, backup to CD/DVD, etc. A free trial is also available.

 

File Naming Conventions

Systematic file names should be worked out in advance of any digitizaiton work. WHO recommends the 8.3 convention, which is an eight-character file name and a three-character extension, e.g. aa000001.xxx. File names should adhere to some general requirements. They should be:

  • Unique and consistent
  • Alphanumeric
  • Lowercase
  • Free of spaces and tabs
  • Numbered sequentially using leading zeroes

 

For more information on file naming, refer to the WHO Digital Imaging Guidelines

 

Quality Control Concerns

There are a lot of factors to consider when planning a digitization project. As you become more experienced and more sophisticated you'll think differentlywhen planning future projects. Modulation transfer function (MTF) is one of those aspects to think about as it can affect the quality of your scans.

 

Modulation transfer function (MFT)

 

Institutional Guidelines and Practices

 


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