IR WorkshopIR WorkshopDigitisationDigitisation

1-3 April 20091-3 April 2009Presented by Presented by

Henning van AswegenHenning van Aswegen

DIGITISATION - ?DIGITISATION - ?

“Digitization is the process of converting information into a digital format. In this format, information is organized into discrete units of data (called bits) that can be separately addressed (usually in multiple-bit groups called bytes). This is the binary data that computers and many devices with computing capacity (such as digital cameras and digital hearing aids) can process.” (whatis.com)

HISTORY OF INFORMATION

PURPOSE

Why do we need to digitise:

For access or preservation? Preservation through access

“The primary use of digital imaging into the near future will be to improve access” - Anne R. Kenney (1998)

Alternative preservation methods “Microfilm possesses two simple advantages over most other

media used for recording information: it is long-lived and it is readable by humans” - Suzanne Cates Dodson (2001)

ABRIDGED LIFE CYCLE OF DIGITISATION

MATERIALS PROCESSES

PRODUCT

PLANNING

MATERIALS

GUIDELINES

Dependant on the purpose of any given institutional repositry

Examples of existing and published guidelines:Selecting library and archive collections for digital

reformatting (RLG, 1996)Digital Imaging Best Practices Version 2.0

(BCR's CDP, 2008)

Example of an existing institutional guideline:Selection criteria for digital reformatting

(National Library of Medicine, 2008)

MATERIAL SELECTION

Questions to ponder:Who owns the rights to the original?Does its nature warant digitisation?What is the physical condition of the original?

Where will it be done?Who are the current and the potential users of the

original?What are the costs and benefits of digitisation?

Kno

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orig

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KNOW YOUR ORIGINALS

Format of the originalPrinted text, photographic material, audio, video, etc?

Condition of the original:Automated processes, conservation required?

Size of the original:Similarly sized originals smooth workflow

Colour content of the original:Colour scanning more expensive and time intensive

IN-HOUSE OR OUTSOURCE

In-house

Pros: Experience

Control

Adjustment

Cons: Large investment

Time intensive

Limited production

Outsource

Pros: Lower cost

Less risk

High production

Cons: Less control

Complex contracts

Lack of knowledge

KNOW YOUR PURPOSE

Cost:

HardwareStaffMaintenance

Benefits:

Increased visibilityEase of access

STANDARD WORKFLOW

MATERIALS

• Select your materials

• Apply preservation where needed

• Use caution where needed

• Send it away for digitisation

STANDARD WORKFLOW

• Digitise the selected item

• Use automated processes where possible

• Manipulate the file to produce different versions

• Ensure digital content survival and accuracy

PROCESS

STANDARD WORKFLOW

• One digital master, highest possible resolution, Tiff format accepted as standard

• Derivative images for access purposes

PRODUCT

TECHNICAL OVERVIEW

DIGITAL IMAGE TYPES

Raster image Vector graphic

RESOLUTION

DPI and PPI

Expressed as dots per inch (DPI) – archeaic term, prefered term for output to printed media - or pixels per inch (PPI) – proper term, prefered for actual image. Refers to the density of information contained in an electronic image file.

BIT-DEPTH

Relates to the level of colour that will be captured. Attached to each individual pixel.

Represents the tonal value of the pixel.

1-bit image has only black and white (1 bit)8-bit image has 256 shades of grey (2^8 = 256

shades)24-bit image has millions of shades of colour (2^24

= 16,777,216 shades)

COLOUR

BITONAL

GRAYSCALE

RGBAdditive colour system

CMYK – Printer ColourSubtractive colour system

FILE FORMATS

JPEGJoint

Photographic Experts group

TIFFTagged

Image File Format

GIFGraphic

Interchange format

Bitmap

SVGScalable vector

graphics

MP3Mpeg 3 audio

encoding

WMAWindows

media audio file

PDFPortable

document format

Audio video Interleaved

DOCMicrosoft

Office Word format

Format description of the Library of Congress

Global Digital Format Registry

BMP

AVI

COMPRESSION ALGORITHMS

• Lossless compression

No information lost Suitable for digital

master

Examples: TIFF

• Lossy compression

Information is lost Suitable for access

version

Examples JPEG and MPEG

RECOGNISED STANDARDS

WORLD DIGITAL LIBRARY DIGITAL IMAGE STANDARDS

ORIGINAL COLOUR FORMAT RESOLUTION

TEXTUAL: Text and text with grayscale illustration

Grayscale TIFF 300 DPI

TEXTUAL: Text with colour illustration

Colour TIFF 300 DPI

TEXTUAL: Papers and periodicals

Grayscale/Colour – Depends on original

TIFF 300 DPI

Pictorial: Images, eg photographs

Grayscale/Colour – Depends on original TIFF

300 DPI/600 DPI if smaller than 125 cm2

Cartographic: Maps and atlases

Colour TIFF 300 DPI

SCANNERS

Flatbed scanner

Overhead scanner

Handheld 3d scanner

Document feed scanner

Large format (A1) scanner

Film scanner

HARDWARE

• Large scale graphics processing

• At least one powerfull workstation

• At least one large backup server

RECOMMENDATIONS

• Scanner determined by collection

• As much hardrive storage as possible

• High end desktop graphics cards

• As much memory (RAM) as possible

• Mid level processor

EXISTING DIGITISATION PROJECTS AND INSTITUTIONAL

REPOSITORIESMichigan Digitization Project

Australian digitisation projects

Europeana

Minnesota Digital Library

World Digital Library

Oxford Digital Library

Native American Constitution and Law Digitization Project

CONCLUSION

Digitisation is a tool not a goal

SOURCES AND ADDITIONAL READING

• UKOLN

• World Digital Library

• BCR

• Ask a geek