Best Practices for Imaging of Text and Graphics

This is not policy, but rather a guiding document. For various reasons, projects might not be able to fulfill these recommendations. At present, technical debt related to storage and access systems makes these recommendations difficult to fulfill.

These specifications remain aspirational, but serious efforts should be made to adhere to them to better ensure the long-term preservation and usability of digitized texts and graphics.

Documents and manuscripts (unbound)

Format	Pixels Per Inch (PPI)	Bit Depth
TIFF, PDF/A	300 or 400 PPI	8 or 16 bits

Modern textual documents, those printed on office paper, may be imaged at 300 PPI.

Newspapers and Serials/periodicals

Format	Pixels Per Inch (PPI)	Bit Depth
TIFF, PDF/A	300 or 400 PPI	8

Oversized Documents: Maps, Posters, Broadsides, ect.

Format	Pixels Per Inch (PPI)	Bit Depth
TIFF	400 PPI	8 or 16 bits

Over-sized materials larger than 34 x 24 inches will need to be stitched together as a composite image. Each individual image should be retained as a master file. A service master may be created to represent the composite from which access copies can be derived.

Prints and Photographs

Format	Pixels Per Inch (PPI)	Bit Depth	Color Mode
TIFF	400-600 PPI	8 or 16 bits	Adobe RGB

Photographic Transparencies

Format	Pixels Per Inch (PPI)	Bit Depth	Color Mode
TIFF	2000, 3000, or 4000 PPI	8 or 16 bits	Adobe RGB

Recommendations for photographic transparencies is dependent on goal of digitization. It may be appropriate to scan transparencies at lower PPI to prioritize access over costs. Transparencies can also be grouped together as another means of cost-saving.