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 specifications provided to imaging vendors that provide scanning services.

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). If you plan to scan oversize materials, bound materials, or materials in non-standard formats and sizes, you may want to consider outsourcing these materials to imaging vendors.

The Hudson River Valley Heritage Digital Imaging 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

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

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

GUIDELINES BY SOURCE TYPE

TEXT

	Master	Access*	Thumbnail**
File Format	TIFF	JPEG	JPEG
Bit Depth	1 bit bitonal 8 to 16 bit grayscale 48 bit color	8 bit grayscale 24 bit color	8 bit grayscale 24 bit color
Spatial Resolution	Adjust scan resolution to produce a minimum pixel measurement across the long dimension of 6,000 lines for 1 bit files and 4,000 lines for 8 to 16 bit files	150 - 200 ppi	144 ppi
Spatial Dimensions	4000 - 6000 pixels across the long dimension	600-800 pixels across the long dimension	160 x 120 pixels (CONTENTdm specification)

PHOTOGRAPHS

	Master	Access*	Thumbnail**
File Format	TIFF	JPEG	JPEG
Bit Depth	16 bit grayscale 48 bit color	8 bit grayscale 24 bit color	8 bit grayscale 24 bit color
Spatial Resolution	400 to 800 ppi	150-200 ppi	144 ppi
Spatial Dimensions	4000 to 8000 pixels across the long dimension, depending on size of original, excluding mounts and borders	600-800 pixels across the long dimension	160 x 120 pixels (CONTENTdm specification)

MAPS

	Master	Access*	Thumbnail**
File Format	TIFF	JPEG	JPEG
Bit Depth	16 bit grayscale 48 bit color	8 bit grayscale 24 bit color	8 bit grayscale 24 bit color
Spatial Resolution	600 ppi 300-400 ppi for larger maps	150 to 200 ppi	144 ppi
Spatial Dimensions	6000 to 8000 pixels across the long dimension	1078 pixels across the long dimension	160 x 120 pixels (CONTENTdm specification)

GRAPHIC MATERIALS

	Master	Access*	Thumbnail**
File Format	TIFF	JPEG	JPEG
Bit Depth	16 bit grayscale 48 bit color	8 bit grayscale 24 bit color	8 bit grayscale 24 bit color
Spatial Resolution	600 to 800 ppi	150 to 200 ppi	144 ppi
Spatial Dimensions	6000 to 8000 pixels across the long dimension, excluding mounts and borders	600-800 pixels across the long dimension	160 x 120 pixels (CONTENTdm specification)

This document was adapted from the BCR's Collaborative Digitization Program's general guidelines for scanning. For more in-depth information concerning this topic please refer to the following source:
BCR's CDP Digital Imaging Best Practices Version 2. (2008). URL: http://mwdl.org/public/mwdl/digital-imaging-bp_2.0.pdf (4 March 2011).

Adopted by the Digital Advisory Committee of the Southeastern NY Library Resources Council, February 5, 2009

* CONTENTdm can generate your access images for you. You can set up your project so that the software will create either JPEG or JPEG2000 files from your TIFFs. If you want to upload an image to HRVH that has more than 800 pixels across the long dimension then the JPEG2000 format is a better choice.

** CONTENTdm will generate thumbnails for your image files upon importing into the system. If you want to create a custom thumbnail for non-image files (PDFs, Audio, Video, etc.) instead of using CONTENTdm's generic thumbnails then they need to be no bigger than 160 x 120 pixels.