Digital Libraries: What are foundations?

Vannevar BushSome day there will be an easy way to store, disseminate, and preserve all of “man’s” knowledge, without leaving your desk.

Knowledge Building Process Problems

• Too much information• Scientists can’t communicate across disciplines• Over specialization, no longer can be generalist• Research slowing because the amount of time

required to know the literature• Knowledge dissemination too slow• Too much repetitive activities, reading, analysis

etc.

Solutions

• Mini-camera—fit on head, size of walnut– Google maps (what are some others?)

• “Dry photography” ?• Compression is a key term• How can we do “math” with letters?– OCR, Natural Language Processing, Text Mining,

Speech recognition ( a la Apple’s Siri)

Another DL Definition

• A digital library is a networked collection of digital objects – text, still images, moving images, sound, data – with arrangement, search features, and metadata that allow for discovery and presentation, supporting research and teaching, and with attention paid to architecture, persistence, longevity, and digital preservation.

Another DL Definition

• Digital libraries are organizations that provide the resources, including the specialized staff, to select, structure, offer intellectual access to, interpret, distribute, preserve the integrity of, and ensure the persistence over time of collections of digital works so that they are readily and economically available for use by a defined community or set of communities. (Don Waters, DLF)

Collections of Digital Works

• "Collections of digital works...." Distinctions among libraries commonly focus on the subject matter that defines the collections (e.g., medical, art, science, music, and such), or on the communities interested in the collected materials (e.g., research, college, public).

Aspects of a Collection

• Respects intellectual property rights

• Is interoperable• Integrates into the

user’s workflow• Is sustainable

• Is built following a collection policy

• Is described so a user can discover its characteristics

• Contains actively managed resources

Types of Digital Libraries

• Stand-alone Digital Library (SDL) – also self-contained, several collections

• Federated Digital Library (FDL)– also confederated, networked

• Harvested Digital Library (HDL)– also distributed

Standalone DL

• A regular DL• Usually localized on server/LAN• Self-contained material:– edited/generated– scanned/digitized– purchased

• Single or Several digital collections

Standalone DL

Federated DL

• Contains many separate digital libraries• Usually heterogeneous repositories• Uses search layer “federated search”• Connected via a network• Forms a virtual library• Unified/Transparent user interface • The major problem is interoperability (does the

metadata cross walk properly? Does it render well?• Example: Brown University Digital Repository

Federated DL

Harvested DL

• Harvests digital objects, not full DLs. • Objects harvested into metadata (using Open Archives

Initiative).• Does not have to contain objects, just

metadata/summaries.• But has regular DL characteristics• They contain the summaries about the objects, and

typically direct you to the home DL if you want to see/hear digital object

• Example: Digital Public Library of America

Harvested DL

Breakdown

Single Digital Library Harvested Digital Library

Items Origin Purchased/Digitized Gathered

Items Location Local/Networked Scattered

Material Items+Catalog Catalog

Repository Size Large Small

Update Medium Fast/Dynamic

CompositionMethod Interoperability Inherent

& Federated

Examples: College or University DL Digital Public Library of America (DPLA)

Acquiring: Digital Collections

The digital acquisition continuum:

New procedures and workflows are required tape loading, scanning, format translation, etc.

linking mirroring hosting archiving

Amount of ResponsibilityLESS MORE

Staffing

• Every DL will require staff– Some designated titles, some part time or cross

trained– Grant funded– Cataloger, metadata specialist– Digital curator– Systems Librarian

• Maybe one designated unit or a blend of staff across departments.

Types of Materials

• Library/archives flavored items– Audio, video, books, images, documents

• Scientific materials– Datasets, raw image data, GIS, Architecture etc.– raw materials that would have never gone on a

book shelf– Gene banks, phonology (speech)

Digitize

• The process of transforming analog material into binary electronic (digital) form, especially for storage and use in a computer. (SAA)

Born Digital

• Born-digital resources are items created and managed in digital form.

• Types: Images, Audio, Documents, Video, data-centric materials, websites

• “electronic records” Data or information that has been captured and fixed for storage and manipulation in an automated system and that requires the use of the system to render it intelligible by a person.

Digitization

• Digitization is the process of converting information into a digital format . In this format, information is organized into discrete units of data (called bit s) that can be separately addressed (usually in multiple-bit groups called byte s).

Acquiring: Image File Formats

Archival version: high-resolution TIFF Online versions:

Preview: low-resolution GIF Full: medium-resolution JPEG High: med./high-resolution JPEG or TIFF

Up-and-coming: MrSID, Flashpix, PNG• Formats– Lossy and lossless– .jpg, .tiff, .raw

Scanners

• Flatbed Scanner– Cheap and relatively easy

to operate. – High resolution, but slow

• Overhead Camera– Fragile items– More difficult– Lighting

Digital Images• Digital Images are electronic snapshots taken of a scene or

scanned from documents, such as photographs, manuscripts, printed texts, and artwork.

• The digital image is sampled and mapped as a grid of dots or picture elements (pixels). Each pixel is assigned a tonal value (black, white, shades of gray or color), which is represented in binary code (zeros and ones).

• The binary digits ("bits") for each pixel are stored in a sequence by a computer and often reduced to a mathematical representation (compressed). The bits are then interpreted and read by the computer to produce an analog version for display or printing.

Digital Image• Pixel: Is the smallest controllable element on a screen• Image Resolution: How many pixels per-square inch• Bit Depth: is determined by the number of bits used to define each

pixel. The greater the bit depth, the greater the number of tones (grayscale or color) that can be represented.

• Digital images may be produced in black and white (bitonal), grayscale (8 bit), or color (24 bit).

• Pixel Values: As shown in this bitonal image, each pixel is assigned a tonal value, in this example 0 for black and 1 for white.