Digital Imaging Guidelines for Hudson River Valley Heritage

The purpose of this document is to offer guidance and to provide minimum digital imaging recommendations to participants in SENYLRC's Hudson River Valley Heritage Digital Service. These guidelines discuss the following components of the scanning process: capture, presentation, storage, and preservation. This document addresses the more commonly used formats of text, photographs, maps, and graphic materials and is written for institutions that already have the equipment and expertise to scan in-house. However, it can also be used as a minimum standard for evaluating proposals from individuals or other institutions to provide scanning services.

If you are planning to primarily scan oversize materials, bound materials, or materials in non-standard formats and sizes, you may want to consider outsourcing these materials to imaging vendors. Inherent or unique characteristics of different source materials necessitate different approaches to scanning and conversion requirements for digital projects should be considered on a case-by-case basis (particularly for grant projects with specific requirements).

The Hudson River Valley Heritage Digital Service Guidelines have been developed in order to:

increase the interoperability and accessibility of digital collections across the cultural heritage community through the use of widely accepted standards and formats

ensure a consistent, high level of image quality across collections

decrease the likelihood of rescanning in the future by promoting best practices for conversion of materials into digital formats and the long-term preservation of these digital resources.

Because technology and industry standards are constantly improving and changing, we view this as a continually evolving document.


TEXT

	Master	Access	Thumbnail
File Format	TIFF	JPEG	JPEG or GIF
Bit Depth	1 bit bitonal 8 bit grayscale 24 bit color	1 bit bitonal 8 bit grayscale 24 bit color	1 bit bitonal 8 bit grayscale 8 bit indexed color (GIF) 24 bit color
Spatial Resolution	300 - 600 dpi**	150 dpi	96 dpi
Spatial Dimensions	100% of original	600 pixels across the long dimension	150-200 pixels across the long dimension

PHOTOGRAPHS

	Master	Access	Thumbnail
File Format	TIFF	JPEG	JPEG or GIF
Bit Depth	8 bit grayscale 24 bit color	8 bit grayscale 24 bit color	8 bit grayscale 8 bit indexed color (GIF) 24 bit color
Spatial Resolution	3000 to 5000 pixels across the long dimension	150 dpi	96 dpi
Spatial Dimensions	100% of original	600 pixels across the long dimension	150-200 pixels across the long dimension

MAPS

	Master	Access	Thumbnail
File Format	TIFF	JPEG	JPEG or GIF
Bit Depth	8 bit grayscale 24 bit color	8 bit grayscale 24 bit color	8 bit grayscale 8 bit indexed color (GIF) 24 bit color
Spatial Resolution	3000 pixels across the long dimension	150 dpi	96 dpi
Spatial Dimensions	100% of original	600 pixels across the long dimension	150-200 pixels across the long dimension

GRAPHIC MATERIALS

	Master	Access	Thumbnail
File Format	TIFF	JPEG	JPEG or GIF
Bit Depth	8 bit grayscale 24 bit color	8 bit grayscale 24 bit color	8 bit grayscale 8 bit indexed color (GIF) 24 bit color
Spatial Resolution	3000 pixels across the long dimension	150 dpi	96 dpi
Spatial Dimensions	100% of original	600 pixels across the long dimension	150-200 pixels across the long dimension

* This document was adapted from the Colorado Digitization Program's general guidelines for scanning. For more in-depth information concerning this topic please refer to the following source:
Western States Digital Imaging Best Practices. (2003). Colorado Digitization Program. URL: http://www.cdpheritage.org/digital/scanning/documents/wsdibp_v1.pdf (22 October 2007).

** Hudson Valley Heritage is considering DPI (dots per inch) and PPI (pixels per inch) to be interchangeable for the purposes of this table.

Adopted by the Digital Advisory Committee of the Southeastern NY Library Resources Council, February 3, 2005