Introduction to digitising bound volumes
Bound volumes such as books need to be digitised with care to avoid poor quality capture or damage to the book. This document looks at the specific problems posed when capturing bound documents and compares commonly used digitisation devices.
Generally speaking the only limiting factor when digitising 2D objects is size, there is a good choice of scanners available for digitising objects smaller than A3 and at high quality. For objects larger than A3 or for bound documents our options become more limited. Flatbed scanners require the original to be pressed flat against the glass, this will often weaken or damage tightly bound books and destroy fragile items.
With the increasing popularity and improving quality of digital SLR cameras the copystand is increasingly being used for digitising oversized or bound documents. The copystand and camera combination is capable of capturing high quality files though the workflow is quite slow and technically challenging and is mainly used on smaller projects or for one off images.
For large book digitisation projects a dedicated book scanner is probably the most efficient and expensive solution. These scanners are designed to digitise a book without placing it under unecessary strain. Some models also offer a partial automation combined with software features that speed up the process, improve quality, and add to the user experience with options such as OCR.
Books and other bound volumes
Before we compare the different solutions it is important to consider the problems we face when digitising bound volumes. The main issue with digitising books or other bound volumes is the binding, this often prevents the book from fully opening so it cannot be held flat on a scanner or copystand. The binding curves the area between pages (gutter) and will distort scanned text or images and reduce the amount of light reaching the spine. If scans are to be OCR'd then any distortion of the text at the centre of the book will lead to an increased error rate. Putting pressure on the page will reduce the curvature however, this will place considerable strain on the book, a solution is to place the book in a special 'V' shaped support or book cradle and capture with a copystand. Book cradles may be off the shelf or home made and should be adjustable to support different thicknesses of book.
Books can be easily damaged just by handling, even modern publications are put under stress when they are opened or handled so the operator should always take care when handling and scanning a bound volume. Some book scanners have features which speed up the process however care should still be taken when turning pages between scans.Poor handling can result in loose leaves or broken spines it is essential that advice is sought from a specialist conservator before digitising rare or valuable books.
Most books are printed double sided; if the paper is thin the print on the back of the page may show through when photographing or scanning. This can be reduced or eliminated by placing a piece or black paper behind the page being digitised.
The pictures in printed books are normally produced using halftone screens, when scanned an interference pattern known as moire may appear. Moire patterns can be reduced with the scanner software and are less of an issue when the material is captured with a camera.
Common capture hardware
Flatbed scanners are designed to capture thin 2D objects, books can be placed upside down on the glass with care but the design of the scanner and the shape of the book will prevent the scanner from capturing page detail in the gutter. One solution for books of no material value or for rapidly and irreversibly-deteriorating books is to carefully cut them from their bindings and digitise them with a standard flatbed or an automated document scanner. Some books have curved bindings, which make pages at the centre of the book thinner than those at the front and back. Automated scanners are designed to handle similar sized pages and may jam with irregular sized pages. You can find more information in our document on Scanners
The copystand mounted digital camera is another commonly used solution for digitising on a small scale. This method places less stress on the book and with the careful use of supports and lighting it should be possible to capture detail in the gutter. Fragile objects should be lit with care, incandescent lights produce a lot of potentially harmful infrared energy, fluorescents or LED produce very little heat and are normally less harmful. Once the camera is correctly positioned above the book it should be possible to operate the camera from a tethered PC. A copystand may be slower than scanning but it is capable of achieving high quality results. You can find more information ain our document on copystands
Copystand, image courtesy of Kaiser Fototechnik
For larger projects it may be more cost effective to use a dedicated book scanner. Book scanners sometimes known as planetary scanners are essentially sophisticated versions of the copystand-mounted camera. Some models make use of the ambient lighting; higher end models have built in lighting systems, which can direct light into the book's gutter. Book scanners often have built in book cradles and bespoke software applications which speed up the capture workflow. The software may also offer features such as automatic OCR, curvature removal and digital finger tip removal when the pages are held flat manually. For more information on planetary or book scanners look HERE( when it is written)
Zeutschel book scanner
The solution you choose will be based on your budget, the condition and value of the original, its size and the volume of work you have to do. If you need the highest possible quality with the minimum impact on the original and your budget will not stretch to buying a dedicated book scanner a solution may be to outsource the work. We have created a list of digitisation services some of which will digitise books.