Basic Digitization - Scanning Toolkit

Topics include: Scanner v. Digital Camera-Pros & Cons Basic digitization terms Some common file formats Types of scanners available Things to consider when choosing a scanner A brief scanning how to

The advantages and disadvantages of digital cameras and desktop scanners will be compared on the following slides.

Advantages

Portable for field use

Useful for large format items (ex. maps, posters, & 3D items)

Disadvantages May require

additional equipment (ex. tripod, lights, light stands)

Variations in quality of material (ex. quality of lighting, focus)

Advantages

Ease of use Clarity of images DPI is able to be

controlled Consistent quality Useful for photos,

printed material, & paper documents

Disadvantages

Not portable without a laptop

Not useful for 3D objects

Scanners commonly use light sensors arranged

in a grid-like array to convert light into 1s and 0s that computers can read and translate into

digital copies of the item being scanned

Scanning is a common way to digitize existing materials

Photographs Documents Some small objects

• Bit-The smallest unit of data that can be stored in a computer

Scanners use multiple bits to represent information about pixels of an image

• Pixel-Short for “Picture Element”; Refers to a single dot in a digital image

Individual color pixels of digital images have 3 numerical components which represent a value for Red, Green Blue (RGB).

• Bit Depth-Number of bits used to define each pixel; also called dynamic range

Each single bit is made up of 2 tones• 1 bit (21) = 2 tones• 2 bits (22) = 4 tones• 3 bits (23) = 8 tones• 4 bits (24) = 16 tones• 8 bits (28) = 256 tones• 16 bits (216) = 65,536 tones• 24 bits (224) = 16.7 million tones

Compression-Reducing file size for easier storage, faster processing or faster transmissionLossless compression-shrink file size without discarding any information

Lossy compression-small bits of information are discarded; may or may not impact visual perception

Scaling-changing proportions of an image by increasing or decreasing size; important when printing images

File formats-made up of bits that comprise an image, and header info that describes how to interpret the file

JPEG (Joint Photographic Experts Group)

Compression standard primarily used for still images on the WWW. JPEG is traditionally lossy compression; not particularly good for archiving images

JPEG 2000

new image compression standard that allows for greater compression while maintaining high image quality; also has a lossless option

Not widely supported by scanners or software

TIFF (Tag Image File Format)

very good for archiving images; a widely supported format; supports lossless compression; larger file size than JPEG

PNG (Portable Network Graphics)

not as popular as TIFF or JPEG, supports high quality lossless compression, particularly for 24 bit photographs; PNG lossless files generally smaller than TIFF

Flatbed ScannerMost common type of scanner; Easiest to use; vary widely in terms of cost; entry level units can be less than $100; many have attachments for scanning slides

Sensors and light source mounted on moving arm sweep past media

Flatbed scanner

What types of materials are going to be digitized?May dictate what type of scanner you buy—flatbed, sheetfeed, film scanner etc. A flatbed will most likely be used for image scanning

CostFlatbed scanner prices range from under $100 to thousands

ResolutionScanner Resolution typically measured by 2 numbersex. 1200 x 2400

Smaller number is most important; refers to optical rating of scanner; a 1200 dpi scanner takes 1200 color samples per inch

Resolutions greater than optical rating are interpolated (some scanners list ratings as high as 9600 dpi)

Interpolated scanning estimates pixels of average color between real pixels

Pictures may come out blurry

Size of scanning surfaceLargest flatbed scanners typically 12 x 17

Anything larger will have to be done with large format setup or shot with a digital camera

Many flatbed scanners are designed for ease of use

Higher end models generally have more features and more advanced image software which can make use more complex

Most flatbed scanners and software vary, but basic use is similar

Step 1: Install software that was bundled with scanner

Step 2: Lay item face down on scanning surfacePosition as straight as possible, for best results

Step 3: Open scanning software on your computer

From File menu, select Scanner Setting; can set:

Scanning Mode Page Size Resolution

Mode will depend on source material

If scanning TIFF for master files set dpi to max level

If scanning JPEG 300 dpi is minimum acceptable level, 600 will likely soon be the standard

Next select File, then scan page

A pre-scan image is shown

Make adjustments here if desired When satisfied press Green button for final scan

From this screen you can make some minor adjustments to picture before saving it

Click Save Icon (Shown on previous slide) Give Picture a File name Choose File Type (TIFF, JPEG, Etc.) Choose Where on your computer you want the image saved Click Save

Some scanner software allows for more image manipulation than others

Software packages like Adobe Photoshop or Gnu Image Manipulation Program (freely available) and many others can be used to manipulate/enhance images after scanning

TIFF excellent for archiving or making high quality prints; can derive JPEG or other file types from TIFF images

Very large file sizes—much storage space needed

If you plan to edit photos beyond basic cropping etc. TIFF format is preferable

JPEG are compressed image filed Developed for use on Web Much smaller than TIFF Great if your are most interested in

displaying pictures online, or making smaller sized prints

Not good as master files if you plan to manipulate images

Quality degrades when file is saved and re-saved

JPEG is best format for images in a CONTENTdm image collection

Small size makes JPEG files ideal for FTP transmission to server

You may however want to keep a TIFF back up of certain images on disks or a hard drive at your own institution, if space permits

If you are not planning to edit picture, JPEG backups are better than nothing

Reviews of Scanners can be found at several websites:

CNET-www.cnet.com Epinions-www.epinions.com, search

scanners Type “scanner reviews” into GOOGLE, or

any search engine www.scantips.com – Gives good basic and

advanced information about scanning

Adam NorthamDigital Collections Librarian

Email: [email protected]

Phone: 903-468-8738