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How to digitise slides. Recommendations and working lists for the reproduction of a very special artefact

Four models how photographing of slides can be done

The following section describes briefly several ways to photograph slides. These are applicable to a variety of collection situations (huge-small quantity of slides, internal-external ownership), useful for different intentions for the reproduction (from thumbnail as memory-aid to long-term storage file, from smartphone SIM card to digital asset management systems), changing infrastructures (from poor to rich in resources and equipment) and heterogeneous motivations (from purely giving access to digital replacement of the original) that lead to digitising slides.

 

A still-camera (possibly with video function) or a video-camera allow a broad approach, as the photographer can add tools to depict the artefact as faithfully as technically possible, but can also arbitrarily “optimise” and even by error, clumsiness or unfortunate circumstances falsify the reproduction while taking the picture. The scanner as reproduction instrument is abandoned here. As flat-bed scanners are standardised, their differences lay mostly in the device’s technical characteristics (e.g. size of the surface, resolution of the sensor) and the used software with its potential settings, not so much in the handling a working situation. The digital simulation of the slide is restricted to its two sides taken frontally by a lens at an unchangeable distance and with an identical light source which doesn’t give much creative liberty to the scanner-operator.

 

The “collection situation” determines the circumstances in which a collection is digitised, the opportunities, but also the limitations a photographer has to deal with while doing her/his job. What s/he wishes to obtain can be different to what s/he finally gets. Keeping this in mind, it is obvious that not all envisioned targets can be achieved in all situations, and that the photographer has to be realistic in evaluating the potential of the digital reproduction.

 

As to the multiple “intentions” an archive can have for the use of its data, a parameter for quality is proposed by Metamorfoze, the Dutch preservation programme for paper heritage which is also applicable for slides. The guidelines divide between the “preservation master” and the proxy which is called “output (derivatives)”, between the highest achievable quality and the lower levels of digitisation.

 

They following approaches demonstrate four quality levels in the digitisation of a slide collection. Questions concerning e.g. the technical equipment are left aside as the section “Practical examples of accomplished digitising projects”  as well as the technical explanations in the section “What happens technically when we digitise?”  have treated these issues widely. All four examples are professional methods; they just vary in circumstances and the room for manoeuvring they allow for, and they envisage different targets. Here the relation between “intention” and “collection situation” can only be treated roughly; however, the four models should give an idea how they influence the quality and the “spirit” of the digitisation to be undertaken.

 

  1. Model “Top-notch”

 

This model corresponds to the maximum effort required by Metamorfoze: “The preservation masters […] must be of such a quality and measurable relationship to the original, that they can in fact replace it. This means that all the information visible in the original must also be visible in the preservation master; the information transfer must be complete since the original is threatened by autonomous decay and will no longer be used once it has been digitized.” (Van Dormolen 2012, p. 4) A file that can be considered acceptable as replacement needs to be true to the aesthetics of the original. The reproductions has to not only to give the human eye the impression of being identical to the document, it has also to be proven faithful when analysed with measuring tools. (Nota bene: In this context, the mentioned standard serves as philological orientation point and doesn’t refer to Metamorfoze’s technical image criteria to which not everybody would agree).

 

The intention of the Metamorfoze Preservation Imaging Guidelines is clear: to have a substitute for the original in case it starts to disintegrate or even gets lost. Therefore, the author, Hans van Dormolen from the National Library of the Netherlands, proposes standardised rules to be followed: “The technical digitalization level is constant; the technical quality is predictable [… and] repeatable; the technical digitalization level does not depend on camera brand and camera type […. nor] on photographer or operator; the quality level is clearly described.” (Van Dormolen 2012, p. 23-24) The author has developed his ideas for “mass digitalization of unequivocal source material” and in regard to colour reproduction. In the context of “How to digitise slides. Recommendations and working lists for the reproduction of a very special artefact” it is submitted as a potential reference line to assure a homogeneous quality level, even for smaller collections, knowing that only a very small number of archives can afford to fulfil the requirements.

 

The collection situation is seemingly “comfortable”: a high standard in financial and personal infrastructure, excellent equipment, and sufficient time. The highest requirements are applied as to the quality of the reproduction, thus the best equipment is employed to meet the needs of the different slide categories, as well as the most favourable working situation (atelier) that a specialist in photography could wish for. The standards are strictly followed for each slide, no compromise is allowed for whatever reason, to allow an exact comparison between the objects.

 

The statement “all the information visible in the original” can be interpreted as does e.g. Ludwig Vogl-Bienek in his research project “Screen1900”, organised by the Department of Media Studies at University of Trier (see project number 3.6 in the section “Practical examples of accomplished digitising projects”).  Next to preserving “all the information” of the artefact, he wants to keep the three dimensionality of the slide (its solidity shown in “3D”) which leads to the reproduction of the object’s two sides carrying the image, its four edges and one additional shot from a lower angle with the slide half-erected and one corner directed toward the camera to create a perspective in depth. He also films movable slides to demonstrate their mechanics and the effect they produce. The intention is to show the slide in all its dimensions to a user whose main interest is doing research on lantern slides. By documenting exhaustively every detail, Vogl-Bienek applies the parameters of a historical-critical edition to a slide collection. The use of a high resolution permits to enlarge the photograph several times without it becoming blurred; this ample degree of enlargement is needed to reveal details which are invisible or hardly detectable to the naked eye.

 

Equipment Excellent: photographic atelier conditions with camera stand, light box, supplementary spots and other accessories, including video capturing, plus scanner for flat documents
Quality 100% true to aesthetics, no digital modification in post production
Reproduction 2 faces + 4 edges + 1 “3D” + 1 video
Target The whole collection
Simulation Suitable for all purposes: from high resolution archive master to low resolution file
Staff Highly qualified by training, self-study and experience (i.e. training paid for, training out of self-motivation, internal application of learned topics)
Infrastructure Digital asset management for long-term storage
Intention Use as master to replace the original in case of loss, digital access to research object

 

  1. Model “High-class

 

Also for this model, the above-mentioned Metamorfoze standards serve partly as point of orientation. A high-quality preservation master file to serve as matrix for the “derivatives”, a precisely established quality level that is kept constantly during the whole work-flow, an excellent equipment in a stable working area are necessary requirements for excellent digitisation results. The “first file” of the work-flow (if possible in RAW) should stand a “close up-check” which shows the image overall sharply and without artefacts when enlarged. A multiple enlargement of the digital picture on the computer monitor should be possible up to a percentage defined by the archive itself and based on its intentions for use (for instance poster printing in A0 or bigger). The potential to “blow up” the shot on the screen to allow research of details would be welcome, as this would enable the replacement of the original by its digital image, maintaining the artefact stored under conservation conditions and its removal from the vault only when absolutely necessary (e.g. for special occasions such as an exhibition).

 

The difference between “top-notch” and “high-class” may be due to the (financial) limitations most archives suffer from. The photographer doesn’t have to be one by profession: as smaller archives cannot afford such a position, staff from e.g. restoration or documentation departments have to do the work, and do it whenever there is time; however, they need training and must also have acquired a certain experience before starting the job. To keep the number of invested working hours as low as possible, slides are photographed on (one or) both side(s) which contain(s) the principal information, and possibly one edge, if additional data can be retrieved.

 

The precise description by Ine van Dooren (Screen Archive South East (SASE) at University of Brighton) and Roy Webster (photographic expert and IT specialist at University of Brighton) give one example (see project number 3.5 in the section “Practical examples of accomplished digitising projects”).  Here the “collection situation” can be called ranging in-between “excellent” – as only a part of the collection had to be treated – and “acceptable” as the archive disposes of an infrastructure which enables it to realise projects up to a certain size, but it suffers from general limitations in time, staff and budget. However, its overall situation made it possible to digitise slides with excellent equipment, knowledgeable staff and sufficient time, thus SASE’s parameters are ideal for a short time project.

 

Equipment Excellent: photographic atelier conditions including video with camera stand, light box, supplementary spots and other accessory, eventually scanner for flat documents
Quality 100% in aesthetics, no digital modification in post production
Reproduction 2 faces + x (x = where additional information can be found)
Target Part of the collection
Simulation Suitable for all purposes: from archive master to low resolution for digital use
Staff Qualified by training and experience

(i.e. formation paid for, internal application of learned topics)

Infrastructure Digital asset management for long-term storage
Intention Use as master to create proxies, digital access to research object

 

  1. Model “Compromise”

 

The requirements are lower than for the two first models. This procedure envisions a compromise between “high-class” and “flexible”. The digitising project serves to document the collection, thus the shots should have a certain quality level that allows lower resolution “derivatives” e.g. for online presentation or video films for exhibition. As the “collection situation” is not ideal, the digitisation focuses on the content of the slide, not its materiality, thus the reproduction cannot pretend to be absolutely faithful to the artefact’s colour. Nevertheless, the pictures should be the best which the (amateur) photographer can get out of the available tools and working conditions. As the records will probably not be high standard right from the start, a manipulation in post production is envisaged to correct too obvious flaws. The intention is not to create “research files” or preservation master, but to show the richness and beauty of the archive’s collection to a broader audience.

 

Equipment Good: stable (temporary) working area with camera stand and/or light box, supplementary spots
Quality Less than 100% in aesthetics depending of the working conditions, (possible) correction in post production
Reproduction 1 face + x (x = where additional information can be found)
Target The entire collection
Simulation Suitable for selected purposes
Staff Qualified by self-study and experience (i.e. training out of self-motivation, internal application of learned topics)
Infrastructure Database for metadata incl. thumbnail, digital storage on hard drives and DVDs
Intention Use to give online access to the objects and present the collection, use for the internal database to get an overview and quickly retrieve an item, not suitable for research as reproduction has limited informative value

 

  1. Model “Flexible”

 

This approach is highly context-dependent as it concerns the “collection situation” inside and outside the archive. Inside, the photographer has to meet the requirements the archive imposes and work with all the tools the archive can give. Outside, e.g. during the visit to a collector or another institution, the photographing depends on the circumstances, the work is done with what is at hand. The photographer has to be extremely qualified as s/he has to act very flexibly according to the situation which is often unpredictable. When travelling “light” (i.e. with a minimum of technical equipment, just the camera and a mono- or tripod, if possible a small light box), it needs creativity to get the best out of the given facilities and the available time frame. The visit to a collector’s home means that time, space, lightning conditions are restrictions which are often difficult to deal with. Challenging limitations can be often overcome with the skill to improvise, low expectations and the awareness of the pitfalls this method implies.

 

The shooting will not lead to preservation masters. However the creation of “access files” in low quality can serve as “memory aid” to remember what the collection contains; it can produce – after some adjustments in post production and without the ambition of “high fidelity” reproductions – decent pictures for the internet. Some ideas about this way of working are given by Sabine Lenk, researcher related to the research group “Visual Poetics” at Antwerp University (see above project number 3.2 in the section “Practical examples of accomplished digitising projects”).

 

Equipment Flexible according to the situation, with camera stand and/or light box
Quality 80%-50 % in aesthetics, correction in post production if necessary
Reproduction 1-2 faces + x (x = where information can be found)
Target A small collection in its whole or the most interesting slides, according to the circumstances
Simulation Suitable for selected purposes
Staff Highly qualified by training, self-study, experience and creativity

(i.e. paid schooling, self-motivated education, in-house application of learned topics, improvisation)

Infrastructure Digital asset management for long-term storage
Intention Use as memory aid and for online access to present the objects; depending on the circumstances the files are suitable or not for research about the slide’s content as the reproductions can have (very) limited informative value