Digital Asset Management

Digital Asset Management

Standards Review

Digital Asset Management: Still Image Standards

Copyright Standards

The legal use of images is guided by a several policies and procedures that include the College’s Intellectual Property Policy, and Information technology policies.  Misusing those rights places both you and the College in jeopardy.  “Fair use” standards for visual materials are especially rigorous, and you must be certain that the intended uses in your digitization project do not infringe on the rights of others.

For more information visit http://academic.bowdoin.edu/copyright/

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Security and Permissions Standards

One of the strengths of digitization of resources is that it makes those resources accessible to many people.  However that strength can become a weakness if proper security is not put in place.  In addition to Institutional security practices there are a couple of strategies that should be built in to any digital project.

  • access to archival master files should be limited.
  • workflow should prevent any changes to the master files.
  • derivative files should be the ones delivered to users. 
  • there should be a clear copyright statement attached to all file

Security Standards

All faculty, staff and students must comply with Bowdoin’s Information Technology policies as outlined at  http://www.bowdoin.edu/about/admin/

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Budget Standards

  • Purchase of images – approximately $7.00 per image depending upon vendor
  • Hardware and software – contact IT
  • File storage – contact IT
  • Staff time – when digitizing an image you should plan on 20 minutes per image to scan, edit, and manage.  If you are not experienced at scanning or image editing, you should budget for 30 minutes per image.

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Software and Hardware Standards

Because computer models, peripherals, scanners and software versions change so quickly, it is important that you contact IT to get the most recent standards.  The staff will assist you in selecting the correct equipment for your project.

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Metadata Standards

To promote reliable searching and basic file management practices, Bowdoin College recommends the use of the Dublin Core descriptive metadata standard for digital image databases.  The Dublin Core allows for a wide range of detail, from very simple to extremely specific, and it accommodates considerable flexibility in customizing descriptions (such as adding non-standard fields) for a particular set of objects.  Because this standard is well established and applied internationally, adopting the Dublin Core assures consistency and reliability for indexing, retrieving, and managing data for immediate applications and over time.

Field
*Required?
Definition
Examples
DC element
File name (system supplied)
M
 Assigned file name, including extension, of the digital object filename.tif;
filename.pdf
identifier
Date digital (system supplied)
M
 Creation date of digital file Scan date; “born digital” date
date
File type; size; resolution (system supplied)
M
 Type of image file; byte size; DPI TIF; 5.8 MB; 600 DPI
format
Title
M
 Formal name given to the work (or work from which image derives); brief caption for untitled work Mona Lisa;
Boy riding a pony
title
Creator or Author
MA
 An entity responsible for the content of the work Artist of a painting; photographer
creator
Administrative Control
M
 An entity responsible for the physical or administrative control of the work A dept. or office that has custody of the work
rights
IP Rights
MA
 Information about copyright and related intellectual property rights The name of a copyright. holder; terms defining use and access of the work or of the digital image
rights
Date original
R
 Date when original work was published or created Date of painting; date of photo; construction date of bldg.
date
Description
R
 Brief summary of the content of the work Free-text narrative of the contents and/or the context of the image
description
Keyword
O
 Topic of the content Topical keywords or controlled vocabulary; LCSH; thesauri
subject
Publisher
O
 An entity responsible for making the work available A person; a dept. or office; the College
publisher
Use
O
 Intended audience for viewing the image or digital project Class no.; project name
audience
Local identifier
O
 Numbering or naming reference to the resource from which the digital image derives Call no.; local file no.
source

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File Storage Standards

Please call IT to discuss file storage needs.

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File Naming Standards

  • Length: 32 or fewer characters, including the extension
  • Include three letter extensions (e.g., “.tif”)
  • Use only one period in a file name, and position it before the three-letter extension; if there is no extension, then do not use any periods in the filename.
  • Use only the characters from the following sets: a-z, 0-9, underscore ( _ )
  • Use all lower case letters

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Scanning

  • Scanning is quite complicated by the fact that there are many different types of scanners and associated software.  All have their own settings and user interface.  However regardless of scanner type or brand, there are several basic concepts to keep in mind that will make scanning easier. 
  • Use the right type of scanner - The selection of a scanner will have the greatest impact on quality of images. It is a challenge to select the right scanner as technology, pricing and scanner features changes nearly everyday. Which scanner is right for your project depends on numerous factors including overall project goals and the format, size, and condition of materials to be scanned, as well as available budget.
  • Optical resolution - The optical resolution of scanner should exceed the maximum resolution needed.  For example, a flatbed scanner with an optical resolution of 1200 ppi has sufficient optical resolution to scan an 8x10” print at 600 ppi, but insufficient optical resolution to scan a 2x2 slide at 4000 ppi.
  • Most scanners are advertised with high resolution.  This is a little misleading in that often these higher resolutions are interpolated; they use a sophisticated guessing system.  Therefore, it is important that you know the true optical resolution of the equipment.
  • Bit depth -The greater the bit depth, the more information about the source is captured by the array, resulting in a more accurate digital representation of the original. A bit depth of 8 can capture enough information to represent 256 colors or shades of grey. A bit depth of 24 (8 bit channel Red + 8 bit channel Green + 8 bit channel Blue = 24 bits) captures over 16 million colors or shades of grey. Since higher bit depths capture more information, they increase the overall file size of an image.
  • The best resolution to scan your images depends on how it will be viewed - on screen or in print.
  • Digital image quality is dependent upon the source material scanned.  High resolution scanning will not improve the quality of a poor image.
  • Scan once.  If the image needs to be resized after the scan, it's always much better to resize to reduce the image size rather than to resize to increase the image size. If you aren't sure what your future intentions for the image might be, and won't be able to scan it again, then err on the large size. Resizing to be smaller discards excess pixels. But resizing to be larger must create new interpolated pixels which were not in the original scan. The results are not at all the same as scanning at the higher resolution.
  • Make color correction with a photo editing program such as Photoshop.  Do not make corrections using the scanner software.
  • Calculate the final image resolution.

There is a direct relationship between resolution and image dimensions.  If a digital image is to be outputted at a size four times greater than the original, then the capture resolutionshould be four times greater than the final output resolution.

To calculate capture resolution for known output:
Longest dimension of desired output (in inches) multiplied by desired output resolution (in pixels) divided by longest dimension (in inches) of original.

EXAMPLE:
To print an 8”x10” image at 300 dpi, scan the original (at 100%) as follows:

  • 8”x10” print at 300 ppi (10x300/10)
  • 1”x1.5” slide at 2000 ppi (10x300/1.5) 

To calculate capture resolution based on desired pixel dimension:
Longest dimension (in pixels) of digital image divided by longest dimension of original (in inches) equals capture resolution.

EXAMPLE:
For a longest pixel dimension of 4000 pixels, scan

  • 1”x 1.5” slide at 2670 ppi (4000/1.5)

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Resolution Standards

Common Image Uses Typical Resolutions Bit Depth
   

Color

Greyscale
Master/archival—Recommended when long-term use is uncertain. 600 dpi (or 4000-6000 pixels across the longest dimension 16 bit 8 bit
Large format printing
(16”X20” and bigger)		 150 dpi 16 bit 8 bit
Printing 300 dpi 16 bit 8 bit
Web 72 dpi 8 bit 8 bit
Presentation 72 dpi 8 bit 8 bit
Presentation: detailed image study 72 dpi, however image dimensions should be increased 16 8
Art print 1200 dpi 16 bit 8 bit

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File Format Standards

  • To ensure long-term accessibility, master files should be saved in uncompressed TIFF (.tif) format.
  • Derivative files to be used for presentations or Web display should be saved in JPEG (.jpg) format.  Note that compression in JPEG files causes some data to be lost each time the file is saved, resulting in image deterioration over time. 
  • Derivative files to be used for printing should be saved in TIFF (.tif) format.
  • Many cameras use proprietary RAW file formats which complicates the conversion to useable formats. It is not recommended that master files be saved in RAW format.

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Color Mode Standards

Any image intended for printing either commercially or on an ink jet or color laser, should be saved in the CMYK mode.

Any image intended for viewing on a monitor should saved in the RGB mode.

Digital images may be produced in black and white (bitonal), grayscale, or color.
Color capture is recommended for most photographs (even those that are black and white to retain subtleties of tone), but this choice depends on the project. For example, bitonal would likely be the best choice for scanning black and white newspaper cartoons.

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Color Space Standards

For input (e.g., scan or digital photograph): Adobe RGB (1998)
For output: Adobe RGB (1998)
For digital presentation such as Web or through a projector: sRGB
For print output (e.g., photographic prints or publication use), color specifications should be set according to the output device being used.  Most labs, printers, etc. will provide color specification settings or do the color space conversion on-site.

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Project Planning Standards
Use of Basecamp, a powerful web-based project management tool is strongly recommended.  To set up your project, contact ktravers@bowdoin.edu. 
 
The plan should specify the following:
Who will acquire, process and catalog the images
The approximate number of images.
Who will use the images
How the images will be accessed and by whom
How the collection will be searched and sorted
What copyright restrictions apply
How many hours the project will require
What hardware and software, (if any), needs to be purchased.

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