What is Digitisation?
Digitisation means creating digital copies of items from your collection. You can do this using a flatbed scanner or digital camera.
Why should we do this?
Digitisation can help you develop your collection:
- By increasing access, especially if a long-term aim of your archive is to establish a community website
- By allowing you to copy archival material lent to you as a temporary loan rather than a permanent deposit
Before you start
- Make sure you have followed the advice in Building up collections: cataloguing your material and developing your collection’s research potential and sub-divided your collection; for example, into subject categories
- Choose batches of items to work on, rather than everything all at once
Using a scanner
The easiest format for digitisation is using a flatbed scanner.
Use this for flat items
- Paper documents
- Slim volumes/books, as long as you handle them carefully, making sure it will not cause damage to their spines.
First make a digital master file
You only need to scan the document once. This should be an accurate representation of the actual document. It should be created at the highest suitable resolution and bit depth. From the digital master, all other copies can be made and these can be amended as necessary.
Make sure the numbering system you apply to the digital image ties in with the archive number you have given the actual document.
An easy way is to add a ‘1’ at the end of the archive number to denote the digital image. For example:
Archive number: 110M85
Digital image number: 110M85_1
Literally data about data
Most organisations that are involved in digital preservation and digitisation also keep metadata records. These cover all the technical information related to an image, usually compiled in a spreadsheet. One advantage of keeping this kind of information is to check if the digital images have deteriorated over time.
Metadata will help support your catalogue records. You may not wish to keep such detailed information about the image, but a few key pieces may be useful, for example, if the items you are digitising are on temporary loan.
Metadata to include could be:
- Digital image number
- Digitising date
- Name of digitiser
- Size of original document (width x height)
- File size and format (ie, TIFF, JPEG, web JPEG)
- Additional notes (ie, copyright information)
It is good archival practice to store images in two locations. If you are working through a large collection of images, transfer them to CD and/or an external USB hard-drive.
- Remember that every archive is unique and the process of digitisation is merely a tool to aid in the formation of your individual collection – don’t let it dictate or take over the project!
- Nothing can substitute for the original document. The emphasis must always be on taking good care of your original documents
- As technology is changing all the time, anything stored digitally has a limited time span
- Digitisation can be extremely useful for building up an image bank, which can then be used for a variety of purposes:
- educational resources
Different types of file formats
Images may be stored in a variety of ways but the two most commonly used file formats are TIFFS and JPEGS.
Tagged Image File Format – an uncompressed file format
- Ideal for saving an archive master file
- Also ideal for print purposes as it is able to handle images saved in CMYK colour format, (four colour process used by many printers)
- Larger file size than JPEG
The name originates from Joint Photographic Experts Group – a compressed file format
- Ideal for saving images as a copy
- Also ideal for creating images which are to be used on the web
- Once saved, its file size will be significantly smaller than that of a TIFF
- May be a loss in image quality if it is repeatedly edited and re-saved
- Image resolution is described as ‘dpi’ – dots (or pixels) per inch
- The higher the resolution, the better the quality of the saved image
- A typical low resolution image will be 72dpi
- A typical high resolution image will be 300dpi
- Bit-depth relates to the level of colour that will be captured
- A ‘bit’ is the binary digit that represents the tonal value of the pixel
- Generally speaking, a 1-bit image is black and white, an 8-bit image has 256 shades of either grey or colour and a 24-bit image has millions of shades of colour
- The file size is the size of the computer file of your image
- It is measured in bytes
- The larger the file size, the more disk space (storage space) this will take up on your computer
- Bytes (1 byte = 8 bits) are often broken down into kilobytes or KB (1000 bytes) megabytes or MB (1 million bytes) and gigabytes or GB (1 billion bytes)
- An average floppy disk has the storage capacity for 1.44MB, a CD has 700MB and an external USB hard drive has 232GB