COURSE 1 DIGITAL LIBRARIES – INTRODUCTION

1. COURSE 1 DIGITAL LIBRARIES – INTRODUCTION UNIT 3 D.L. FUNCTIONALCOMPONENTS - HARDWARE

2. Introduction • Digital libraries born out of computing and network technologies • D.L. require several infrastructure facilities – • Hardware, software, middleware, human ware • Hardware – physical artifacts of technology for storage and speed

3. Functional components- hardware • Digitization devices • Storage devices • Client side devices

4. Digitization devices - scanners • Scanners- peripheral devices • Optically scans images, printed text, handwritings, or an object, and converts it to a digital image. • Typically connect via Universal Serial Bus (USB) • Software provided by the manufacturer or the operating system to scan documents, photos or other items to the computer

5. Scanners- important aspects • Capability and suitability to the material to be scanned • Should be capable to produce requisite quality of material • Image quality – resolution measured in dpi, bit depth, size and compression • Categorized – contact and non-contact

6. Scanner - contact • Contact scanners gather the spatial data of an object by physically probing it. • Contact scanners are used in the manufacturing process to probe smaller objects for one of two purposes: • to produce replicas of a certain object or • to further refine the dimensions of an object that exists in model form.

7. Scanner – non contact • Non-contact scanners do not probe their subject matter • Generally used to record the spatial data of larger objects, including buildings, building systems, sculptures, terrains and specific spaces. • Companies and organizations that use non-contact scanning services use either a time-of-flight 3D laser scanner or a triangulation 3D laser scanner.

8. Scanner – types - flatbed • most common piece of equipment available • compatible for scanning with any personal computer. • Flatbed scanner has a glass plate on to which the source document is laid facedown. • They have increased speed and economical to use. • They allow bi-tonal, grey scale and colour scanning. • Most of them offer resolution of 600 dpi and it is available in 24 bit or 36 bit colour. • They are often bundled with their own scanning software Optical Character Recognition (OCR). • Disadvantage - it relies on contact scanning and is thus unsuitable for rare and fragile material.

9. Flatbed scanner

10. Hardware Computers Networks / Internet Connectivity Web servers Storage media: Hard disk tower and CDs Back up storage CD /DVD/ writers Scanners Digital camera Video digitizer Multimedia interfaces Converters UPS back up

11. Scanners-types -drum • The drum scanner gets its name from the clear acrylic cylinder, the drum. • It allows very high resolution. This rotates and the image read one line at a time through photomultiplier tube technology (not CCD). • Possible to mount originals up to 11"x17"(but maximum size varies) used for relatively big size of documents. • It offers highest resolution up to 12,500 dpi with colour gradation and value structure • Recommended when a scanned image is going to be enlarged. • Disadvantage - extremely expensive compared to flatbed.

12. Drum scanner

13. Scanners- types – sheet feed • Sheet fed scanner - useful for large collection of loose leaf documents and transparent material • To convert the light and dark areas into corresponding image data, the scanner typically illuminates the sheet with a light source. • Benefit - remarkable speed and one can leave it churning through the documents unattended up to 100 pages. • Photocopying the sheets from the bound volumes will be a better option to use the sheet feed. • Disadvantage - unable to deal with fragile or brittle items, oversized documents (usually size restricted to A 4).

14. Sheet feed scanner

15. Scanners- types -book • Book scanners are usually a high quality digital camera with light sources on either side of the camera mounted on some sort of frame to provide easy access for a person or machine to flip the pages of the book. • Some models involved are V-shaped book cradles, which provide support for book spines and also center book position automatically. • The advantage of this type of scanner is that it is very fast, compared to the productivity of overhead scanners. • Compared with traditional overhead scanners whose prices normally high, this type of digital camera-based book scanner is much more cost-effective.

16. Book scanner

17. Scanner – types -microfilm • There may be separate film and fiche scanners • Automatically detect each frame and scan the image. • Necessary to see whether they accommodate 16 mm / 35 mm films to cope with positive and negative images. • Fiche scanners are similar to sheet feeders and can take a stack of 50-100 microfiches at a time. • At higher speed it processes 200 dpi and at lower speed 600 dpi. • The flatbed scanners also provide the facility to scan microforms using film/ strip holders.

18. DIGITAL CAMERA • Sensors - the primary component of digital cameras - made out of silicon. • A digital camera takes light and focuses it via the lens onto a sensor. • The sensors are a grid of tiny photosites that are sensitive to light. • Each photosite is usually called a pixel and millions of these individual pixels are there in the sensor of a digital camera or otherwise known as single-lens reflex camera (DSLR). • There are high level DSLRs with extreme sharpness, excellent image quality, high density and fast image processing with anti-flicker and crop shooting features. • HDSLR is a DSLR camera with the capability for HD video recording. 

19. DIGITAL CAMERAS (Contd.) • The digital camera useful in case of fragile or brittle • High level digital cameras that provide 300-600 dpi and 24 bit colour. • 300 DPI is the minimum quality for an image to be digitized. But that is just the absolute minimum for an 8 x 10. • Depending on the image size to be digitized requirements will vary from 300-600 dpi. • 600 DPI with extra room to crop out a high quality 8”x10” without re-sample and lower the original quality is perfect.

20. DIGITAL CAMERAS (Contd.) • Bit depth - indicates the quantity of colours that are available in an image in terms of 0s and 1s or bits. • Images with higher bit depths can encode more shades or colours as there are more combination of 0s and 1s are available. • Every colour pixel in a digital image is created through a combination of three primary colours or colour channels – red, gree and blue. • Each colour channel have its own intensity specified by bit depth i.e. bit per channel. • Bits per pixel bpp – is the sum of the bits in three primary colours and represents the total colours available at each pixel.

21. DIGITAL CAMERA

22. STORAGE DEVICES • Digital library requires huge storage space with multiple hard disks. • DL in distributed client server environment consists of hardware and software at client as well as server side. • Server hosts databases, digital objects and search interfaces. • Clients are the machines that are used for accessing DL by users. • Server consists of – • Adequate memory • Large space for data / file storage • Good communication capabilities • Scalability for additional storage and processing

23. BACK UP STORAGE SERVERS • File server is a computer attached to a network that has the primary purpose of providing a location for shared disk access • It is designed primarily to enable the storage and retrieval of data • Storage servers are normally individual units built into a 4 U rack mount or consist of two boxes. • They come with a host of specialized services like storage management, configuration and extra network connections. . • The time tested file server technologies are Network Attached Storage (NAS), Storage area networks (SAN) etc.

24. STORAGE SERVER

25. NETWORK ATTACHED STORAGE • NAS system consists of a dedicated data storage unit connected directly to a computer network • It is like any other PC or a server, but stores only files which can be shared by any network member. • The server comes with pre-installed operating system and a file management system (FMS). • NAS uses 2 types of storage technologies • Stripped-down operating system or Thin OS: The operating system if loaded on a chip of the mother board • Redundant Array of Independent/Inexpensive Disks (RAIDS): The NAS server usually consists of multiple hard disks configured as RAID

26. STORAGE AREAS NETWORKS • SAN is a network designed to attach computer storage devices such as disk array controllers and tape libraries to servers. • A SAN allows a machine to connect to remote targets such as disks and tape drives on a network. • SAN support disk mirroring, backup and restore, archival and retrieval of archived data, data migration from one storage device to another, and the sharing of data among different servers in a network. • SANs can incorporate sub-networks with network-attached storage (NAS) systems.

27. CLIENT SIDE HARDWARE • In a networked environment, client is often a Web browser running on a computer that connects the end user to the network server. • Obviously, computers with more memory, hard drive space, and processors tend to make better servers. • The clients have to be provided with devices like PCs, laptops, tablets, mobile devices to get access. • The device should meet certain technical requirements -client side operating system (Windows or Mac), client side browser (Internet Explorer, Google Chrome, Safari).

28. CLIENT SERVER

29. SUMMARY • Digitization activity depends on obtaining a qualitative facsimile of the original. • This can be accomplished with a combination of software and hardware imaging tools. • Hardware tools include storage devices, scanning devices and computing devices at server end and client end. • There are different varieties of hardware available and there is emerging new equipment. • The library professional has to choose the hardware suitable to the project on hand. • Advice from computer professionals will be an added advantage.