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Creating/Processing Digital Images: Some Considerations

Information for the BC Community

Seurat: The Circus

Since every scanner and digital camera works differently, I can't provide step-by-step instructions for creating digital images. Yes, you will need to read the documentation for the device you're using. What I can offer here are some of the things you should think about before you create a digital image, and when you are processing it for display or printing purposes.

Consider the Source

Are you photographing on-site somewhere that you might not be able to travel to again soon? Are you scanning an item that you might not have in hand in the future (e.g., an interlibrary loan book)? Is the reproduction you're scanning of high quality?

If the answer to any of these questions is "yes," you will want to consider creating a very high-quality, uncompressed "master digital image." Although master images are large files (see "Consider Your Storage Capabilities & Needs," below), you will be able to create smaller "derivative" files for everyday use. As the capabilities of our monitors and digital projectors improve, you will always have the master image to return to in order to make appropriately formatted derivatives, thereby avoiding having to track down and re-scan the original image (or traveling back to the site).

If, on the other hand, you're scanning from a poor original, or photographing on-site in a nearby location using a low-resolution camera, there is little point in creating a large digital file. Tailor the size of your file to the way you intend to use it.

Consider How You Intend to Use the Image

Knowing how you intend to use the image — for instance, whether you'll be printing it or displaying it on a monitor or by projector — is important in determining various specifications for the image that you create. Of course, if you have on hand a master version of the image (see above), you can always go back to that large image to create new derivative images for uses that you might not have anticipated when you first created the master image. If, on the other hand, you're creating an image for immediate, one-time use, you may not want to invest the extra time that could be required to create and post-process a master image, much less the space to store it indefinitely.

While creating and maintaining master image files is generally a good practice, you'll want to create derivatives (smaller versions) of those files for everyday use. Very large image files can take a long time to open on a computer and, if inserted into applications such as PowerPoint, will result in extremely large presentation files that will operate very slowly.

For my suggestions for specifications for different uses, see Quick Image Specifications.

Consider Your Storage Capabilities & Needs

If you are traveling with a digital camera, your storage capacity will be determined by the number and size of the memory cards you have. If you plan to shoot a lot of pictures, you may need to set your camera to shoot using a compressed image format, such as JPEG, in order to avoid running out of storage space. Alternatively, you may want to consider bringing along a laptop or portable storage device to which you can download your photographs, freeing up more room on your camera's memory card, and allowing you to shoot using an uncompressed format.

As you begin to accumulate images on your computer's hard disk, you should also think about establishing a storage protocol, both to protect your images and to prevent them from filling up your computer's hard disk. For instance, you could decide to store all of your master image files on an external hard drive, keeping the smaller derivative image files on your computer's hard disk for easier day-to-day access. Keep in mind that hard disks — both external and the one in your computer — and other storage media, such as CDs and DVDs, can fail, rendering your image files irretrievable. Good practice standards actually recommend keeping two copies of your master files on different storage devices (for instance, two separate hard drives, or on a hard drive and on archival-quality CDs or DVDs), in two separate locations.

To help you calculate your storage needs, I provide representative size ranges for different types of image files on the Quick Image Specifications page.

Other Useful Links

Working with Digital Images

Managing Your Digital Images

A few scanning tips (external website)

Universal Photographic Digital Imaging Guidelines (external website)

Boston College Information Technology Services training schedule

Ponte Sant'Angelo, Rome

Images courtesy of Saskia, Ltd.
Top: Georges Seurat, "The Circus," 1891 (Musée d'Orsay, Paris); Bottom: The Ponte Sant'Angelo, Rome (134 AD; decorated in 1688 with statues of angels designed by GianLorenzo Bernini)