The capture stage is a critical process in the digital preservation workflow. Not only will you capture a digital image on camera or scanner but you might need to note other information from the process. Here you'll find best practice guidelines for creating your digital images including advice on proper handling of special collections and archival materials, as well as recommendations regarding appropriate equipment and other resources.
Before you begin to capture your digital images, make sure your equipment is clean, calibrated and in good working order. Keep all scanners and cameras maintained regularly, and if you have not used a piece of equipment for a while, do a practice run prior to starting your project. You might also need accessories such as foam, weights, book cradles or glass plates to get the best results.
The quality of image you capture will be directly related to the quality of item you have, so clean and prepare your items as best you can. You should give each item a unique identifier that can be used to match it to it's digital surrogate.
In many cases the historical items that we digitise are fragile and deteriorating, and the digital copy can be made available to researchers to protect the original from overuse. With that in mind, ideally you will only handle the item once to scan it so you should take the best image you can.
Once digitised you must store (and back-up) the files. For best practice, you should store your files in at least three separate places in case a storage device becomes damaged or inaccessible.
Check through these steps prior to beginning your image capture.
Even if small scale, the capture stage of a digital preservation project may require specific resources that could make the project prohibitive. It is often possible to compensate for shortfalls by adjusting other available resources. Make sure to check your requirements.
Time - It makes sense that the more material you have to digitise, the longer it will take, but there are other factors to consider too. You must also take the time to clean, calibrate and focus your equipment correctly. This will cut down on repeating bad quality scans. You should also take time to group material of similar size together so that these can be digitised without altering your settings. Some equipment may take considerably longer to carry out a scan depending on the resolution, especially if the item itself is large. You should test some items prior to beginning the work in order to get an accurate idea of the time it will take.
Labour - Modern digitising equipment and software means that all of us can capture good quality images without the expertise of a professional photographer, however in some cases you might need to use the services of outside help. For example, it might be more efficient to outsource a large scale scanning project, or to employ a photographer to capture the images.
Finance - Provided you are availing of current staffing, equipment, software and storage levels, this stage does not incur many extra costs outside of existing workflows. You may need to arrange extra insurance for storage of the physical material if it has to be moved off site to an external company.
Equipment -The historical items that we handle are often fragile and deteriorating. You should ensure that you have the appropriate, well maintained equipment to suit your needs so as to avoid damaging the original material. If necessary you could hire the equipment or service required instead of buying it. You might consider collaborating with an organisation that offers a digitisation facility, and as a quid pro quo lend your original archival material for use in an exhibition. See our section on equipment for digital image capture.
Software - Many scanners and cameras come with their own propriety software to help you in setting up and processing your images. This can save time processing substandard images.
For any bound item, a book cradle is a great help when scanning. When used with a glass plate, you do not need to refocus as you work through the pages, as the height of the top page never changes. Set the focus to the underside of the glass plate and adjust the cradle to support the item. Usually you can separate the cradle at the centre to accommodate the spine. This takes pressure off the binding. You should also have foam and/or cloth supports on hand to help 'build up' the itself.
If a binding is very tight you might be able to support the book in an open position and then angle your camera to capture all the right pages first, and then the left. Some software will sort the digital pages in the right order after this process. You may get a curved result with the text at the valley of the spine but this can often be dealt with at the processing stage.
If you are confident that the item can be rebound, or if you have a duplicate copy which is not needed, it might be possible to separate the binding by removing the spiral binding spine, comb or staples.
Where the pages are thin and you are experiencing bleed from the text on the reverse of the page, placing a black card behind the page can help.
If the item is a black and white text document, you could save space by scanning at a low resolution and in greyscale. Scanning to 'black and white' can often pick up ‘noise’ on a page which gives the image a speckled appearance.
Do not touch the front of the photograph. When preparing photographs for digitisation, you should wear gloves. Be careful though as cotton gloves can result in a loss of touch and dexterity, increasing the risk of damage to the photographs. In addition, using cotton gloves may produce lint which can distort the final digitised image. Latex gloves are also an option however ensure the photograph is clear of powder from the glove.
Using glass plates to hold photographs can keep them straight and avoid curling edges.
Care should also be taken when using light sources with photographs as the heat can curl and damage them.
Some scanners will allow you to take multiple clips from the one scan. This saves time, however, try to ensure your photographs are straight to avoid having to rescan or edit the digital image.
Some photographs may have annotations or markings on the reverse side. You might chose to capture an image of the reverse, or make a note of any details for the metadata. In the case of the latter, again it is important to have a unique identifier for each item so you can match this information to the digital image.
Ideally you should use a scanner or camera set up to accommodate the size of the original item. In some cases however, this is not possible and you will have to adjust your plan.
You could scan the large item in sections and use software to 'stitch' it together in post processing.
Another option, depending on the space available is to hang the item or lie it flat. Then set up your camera on a tripod or stand to keep it at a fixed distance.
It might be sufficient to just capture details of the piece in close-up to give an essence of the original.