Here are some general guidelines which I propose should be implemented for both the analog and digital images:
1. As much as possible, properly preserve and do not modify the original analog media; printed photographs, transparencies, acetate negatives, glass negatives or in whatever other original format.
2. Do not do anything that will preclude future standards of preservation. Do not mount or modify any original photographs.
3. Use the best currently acceptable standards of both analog and digital preservation and file formats.
4. For digital files, maintain adequate backup procedures with multiple backups on different devices.
5. Document any special circumstances concerning the images produced.
From the historical standpoint, just as sources are preeminently important for facts asserted in genealogy, it is equally important to establish the provenance of any image. For an example of a detailed analysis of a daguerreotype asserted to be of a prominent ancestor and concluded to be otherwise, see TheAncestorFiles: The Tanner Family Daguerreotype and Conclusion. Also see the links contained in that article to the preceding series of articles discussing the provenance of the daguerreotype.
Most of the photos put online are not only published without provenance, they are copies of copies and asserted as images of specific individuals and families without tying them to specific times or places. This inevitably leads to a degradation of the quality of the images, as well as to misidentifications and inaccurate attribution.
The information about a specific photograph, as much as possible should accompany any posting of the article in a venue where the photograph is connected to a particular person or family. It is preferable to attach the information directly to the image by means of metadata. However, there are not any specific methods for attaching metadata and particularly, such additional attachments, if done by a separate file, may become separated from the original. At the very least, the title to the photo should be descriptive enough to identify the subject matter.
Technical standards for the Library of Congress are found at Standards at the Library of Congress. The links from this page go to many of the exiting industry standards. However, there is a need in the genealogical community for a practical and more easily understood set of standards to be applied by researchers in general.
The basis for the following suggested standards came from Melanie I Sturgeon, Director, History and Archives Division, Arizona State Library, Archives and Public Records in a document entitled Minimum Standards for Born Digital Photography. I have modified Dr. Sturgeon's proposal by updating the technical aspects, adding standards for scanning and modifying other details. I am proposing the following minimum standards for digital acquisition and storing:
Genealogical Image Standards
Minimum Digital Camera Image Acquisition Standards:
Digital Single-Lens Reflex (DLSR) minimum 12 megapixels
Digital “point and shoot” minimum 10 megapixels
Note: The smaller sensors on “point and shoot” cameras can affect
image quality Low resolution images and those taken with mobile phones or
disposable digital cameras do not meet minimum standards and
are not acceptable.
Always set camera at its highest possible resolution setting.
Color images should be in RGB format (not CMYK)
When possible, images should be made and downloaded to a computer in Camera Raw format.
Minimum Scanner Image Acquisition Standards:
Minimun optical resolution
300 dpi [Note: Most flatbed scanner claim very high resolution. However, an optical resolution standard of, at least, 300 dpi is commonly accepted as sufficient for archive purposes. See the Library of Congress:Preservation.
File Formats for both digital cameras and scanners:
When possible, images should be made and downloaded to a computer in raw image format and converted to an acceptable file format. Where capturing the images in raw format is not available, the images should be downloaded to the acceptable file format directly. The acceptable file formats include:
- Tagged Information File Format (TIFF)
- Joint Photographic Experts Group 2000 (JPEG2000)
- Digital Negative (DNG) If the images are downloaded in raw format, they should be immediately converted to Digital Negatives (DNG).
- Joint Photographic Experts Group (JPEG) in some cases on a
- case by case basis.
[Note: many scanners and most less expensive consumer cameras default to JPEG image format. Care should be taken when this is the case to preserve the original image downloaded without modification.]
Graphics Interchange Format (GIFF)
Portable Network Graphic (PNG)
RAW - Most camera manufacturers have created their own “flavor”
of the RAW format. These files are encrypted and
proprietary. This may affect their longevity and readability.
Metadata is descriptive information about an object. To comply with standards images must, at a minimum, have:
- People identified
- Place identified
- Date image was taken
- Copyright information
Metadata should be in a separate tab delimited file or in DNG format
To comply with standards, images must have appropriate filenames.
[Note: Each camera brand has its own method for naming files. Rename files with meaningful filenames. Filenames should be unique to each image
Images should be unedited. Do not
- Color correct
- Adjust white balance
I most certainly accept corrections, suggestions and ideas about how these proposed standards may be generally disseminated and accepted.