The purpose of this product is to mitigate risk for loss of information and fulfill researcher/user expectations and requests. This file is at an appropriate quality level to substitute for the original record if the original record copy is no longer viable.

Still photo negatives and film positives (B&W, color, and monochrome) with a size range of 35mm and medium format up to 4" x 5" (square area less than 20 square inches) where there is a need to ensure that all significant visual information is carried forward.

TIFF, version 6.0 (.tif)
Uncompressed

Bit Depth

• 16-bit grayscale for B&W
  • 8-bit grayscale optional
• 48-bit RGB for monochrome and color (default for all negatives including B&W, grayscale, monochrome and color)
  • 24-bit RGB optional

Pixel Array

• 4000 pixels across the long dimension

Spatial Resolution

• Calculate from actual image dimensions
  • Approximately 2800 ppi for 35mm originals
  • Ranging down to approximately 800 ppi for originals approaching 4" x 5"

Dimensions

• Match original size; no magnification/reduction

Tonal orientation

• Tonal orientation is maintained so that a positive image remains a positive image and a negative image remains a negative image.

Typical file size: For 8-bit grayscale: ~12 MB
For 16-bit grayscale: ~24 MB
For 24-bit color: ~20.6 MB
For 48-bit color: ~73 MB

• Recommended level specified in NARA's 2004 Technical Guidelines
• Capture specification may be higher for specific projects.

The Photographic Imaging, Microfilm and Textual Preservation Lab uses 48-bit RGB as the default for all negatives, including B&W, monochrome, and color, when creating preservation master files. The NARA 2004 Technical Guidelines and FADGI 2010 Technical Guidelines discuss approaches for the creation of production master files, rather than preservation masters, and do not set a default for higher bit-depth. NARA 2004 and FADGI 2010 suggest that 8-bit grayscale and 24-bit color files may be created from 16-bit grayscale and 48-bit color files.

The Digitization Services Branch’s Quality Assurance and Quality Control (QA/QA) program is evolving as new tools and resources are acquired and implemented. We are moving towards more automated and integrated systems to assure the products we make meet the specifications outlined. Digital products created by the Digitization Services Branch are validated against standardized format specifications and signature files when possible. We use a variety of format specific batch evaluation and validation tools both open source and vendor supplied, to assure technical quality level specifications are met. All files, but especially distribution system specific files, are inspected for successful playback in a variety of tools and environments. Additional quality control workflows are in development.

Equipment/System Evaluation
NARA implements scheduled service and calibration protocols according to manufacturer recommendations as well as on an "as needed" basis.

Metadata
Embedded metadata: NARA is working on embedded metadata guidelines for all file types.
Technical metadata: NARA is finalizing technical metadata schemas for all file types.

NARA is developing an in house job tracking order system to better coordinate work at the Branch level.

Item Level Evaluation: Automated File Characteristics Analysis
Fixity: NARA is evaluating workflows to create and validate checksums for each digital file.

For additional QC protocols for products created on the Zeutschel Camera System, please see Quality Assurance and Quality Control for Digital Products Created on the Zeutschel Camera Systems

The Photographic Imaging, Microfilm and Textual Preservation Lab uses the uncompressed TIF file format for preservation master files for all the record types it processes. Currently, NARA does not use JPEG 2000 or other means of compression in preservation master files, including LZW compression within TIF files.

Reproduction master files can be either uncompressed TIF or JPG if compression is required.