RPS Imaging Science Group

The Digital Print. The Complete Guide to Processes, Identification and Preservation. By Martin C Jürgens. Thames & Hudson ISBN 9780500514986 25.30 x 20.30 cm 328 pages. For more details see http://www.thamesandhudson.com/9780500514986.html
This book, published in the UK by Thames & Hudson is first and foremost a quality product. Hard backed and printed on smooth, heavyweight paper stock it reproduces both the text and the many pictures and diagrams well. In an era of poor quality book production this stands out as an asset to the bookshelf.
But what of the content? The book is laid out in 4 parts plus detailed appendices and does not disappoint. Clearly meant as a reference book, rather than to be read end to end there is content here of interest to both the photographic student and the established conservator. It can however be read as a journey to the understanding of the digital print and its failure mechanisms.
Part 1 “Understanding Digital Prints” covers the history and current applications of digital printing plus the component materials of the print. For me the history was a great read as I remember lots of the illustrations from university days. The components part of this section introduces 2 visual strengths of this book – Martin’s clear diagrams and the liberal use of cross sections visualised using a microscope.
Part 2 aims to summarise the major digital printing processes used for photographs. The illustrated chapters cover technologies such as inkjet, electrophotography and conventional silver halide based systems. These are well written but my only criticism would be that it is too comprehensive. As a reference work for the future it would be easy to confuse some of the minors with the mainstream technologies.
Part 3 details the visual inspection techniques that allow a viewer to distinguish the various printing technologies. As such it is particularly applicable to conservators and collectors. This section is well laid out with 2 page summaries of the characteristics of the main technologies at the end.
Part 4 then looks at all the issues that pertain to the preservation of the print. The typical failure routes (heat, light, pollutants and humidity) and the standard tests for these are documented accompanied by a good series of illustrations. Finally an excellent series of recommendations are given based on Martin’s wide knowledge and experience of these materials.
The book contains a comprehensive reference list that is of great value for those with access to suitable library resource plus a large identification flowchart in a pocket inside the back cover. The volume is a valuable resource for the photographic printer, conservator and collector and I thoroughly recommend it.

For the photographers amongst us, here is an interesting document. The screw that holds your camera to the tripod is subject to its own ISO standard – ISO 1222. See http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=33323&commid=48420 for details. If you want to get a copy, hold fire. The 2010 version will be out soon!

I find this information doubly useful for attaching imaging kit like telescopes onto tripods.

The new ISO 5 density standards are now featured in a press release from ISO – see http://www.iso.org/iso/pressrelease.htm?refid=Ref1276. This page contains lots of useful links to the other photography standards too.

As promised, the report and presentations are now on line – see http://www.rps-isg.org/DF2009_presentations.php .

The image stability of modern photo print materials is getting very high. As a result, getting valid testing regimes that do not take years to demonstrate failure is difficult. The current tests for predicting the stability of colour photographic images are based on an adaptation of the Arrhenius method. This test methodology is important enough to warrant a standard in its own right – ISO 18924 “Imaging materials — Test method for Arrhenius-type predictions” – see http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=28495 .
Although this method is based on sound chemistry, the validity of its application to predicting
changes of photographic images rests on empirical confirmation. History is on our side – many chromogenic colour products yield image fading and staining in both accelerated and non-accelerated dark ageing tests that are in good agreement with the Arrhenius relationship.
However, we may be lulled into a false sense of security on this as some more modern products show significant deviation from this ideal behaviour. Some exhibit atypical staining at elevated temperatures; others abnormal image degradation, colour balance and saturation.
In particular, some photographic materials can undergo dramatic changes at relative humidities above 60 % owing to changes in the physical properties of gelatine and other binder materials. Lower maximum relative humidities may need to be tested for some of the more humidity-sensitive inkjet materials because of phase changes such as melting point or glass transition temperature.
Maybe Arrhenius has had his day!

ISO technical Committee 42 (Photography) has a good number of standards currently under development – see http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_ics_browse.htm?ICS1=37&ICS2=040&ICS3=20&development=on . A number of these pertain to image permanence and I am now project leader for a new standard – ISO 18936 “Imaging materials — Processed colour photographs — Methods for measuring thermal stability”.  This document covers the methods and procedures for measuring the long-term, dark storage stability of colour photographs.

The length of time that photographs are kept can vary from a few days to many hundreds of years. Often the ultimate use of a photograph may not be known at the outset. Knowledge of the useful life of colour photographs is important to many users, especially since stability requirements often vary depending upon the application. For museums and archives, and photographers in general an understanding of the behaviour of these materials under various storage and display conditions is essential if they are to be preserved in good condition for long periods of time.
The three main factors that influence storage behaviour are the temperature and relative humidity of the air that has access to the photograph, as well as atmospheric pollutants to which the photograph is exposed. High temperature, particularly in combination with high relative humidity, will accelerate the chemical reactions that can lead to degradation of one or more of the image colorants.
Low temperature, low-humidity storage, on the other hand, can greatly prolong the life of photographic colour images, for typical materials. Other potential causes of image degradation are micro organisms, and insects.
A draft of this standard is currently out for ballot. As project leader and UK Technical Expert I welcome your opinion. If you feel you have some input to this standard leave me a comment!

BS ISO 10505:2009 “Photography — Root mean square granularity of photographic
films — Method of measurement” is now available – see http://www.iso.org/iso/catalogue_detail.htm?csnumber=50747. This standard brings the measurement of RMS granularity of film up to date. It pertains to the measurement of monochrome and colour film granularity so it does not cover the perceived graininess of prints directly.
The standard contains a good explanation of the workings of a microdensitometer and the hazards associated with partial coherence in these optics. The work also puts these measurements on a sound statistical footing.
The standard has been a long time in coming but a worthy addition to an Imaging Science library!

The new edition of ISO 14524:2009 “Photography — Electronic still-picture cameras — Methods for measuring opto-electronic conversion functions (OECFs)” is now available from ISO – see http://www.iso.org/iso/catalogue_detail.htm?csnumber=43527 . This contains a host of useful information on the ways in which the tonal characteristics of digital still cameras can be quantified. The test methods and charts therein are equally applicable to fixed lens, SLR and multispectral cameras. For those wishing to understand the variables involved, it is worth a read.
The document also has some interesting hints as to why infrared blocking filters, used to reduce a number of focusing and colour effects need to be considered in camera testing.
This document should shortly be available from BSI too.

I have added a link from this blog to that of a colleague. Mark Mizen is based in Minnesota and writes a blog called All About Images – see http://allaboutimages.wordpress.com/  . I know Mark from the ISO working group on Image Permanence and from the conference circuit. The blog has some interesting general views on photo imaging.

Take a look and leave him a comment – I usually do!

This is more than just a conference – it is 23 individual meetings under one roof at one time. I am looking to attend this meeting, scheduled for 17 – 21st January in San Jose, California. I have just received the Call for Papers and thought I would share my initial thoughts with you.
There are a number of the conferences that caught my eye.
1. Color Imaging. Amongst other content this looks at the use of colour in documents and extra spectral attributes such as paper UV fluorescence and IR behaviour. Phil Green of the London College of Communication is one of the organising committee so would be a good point of contact for this meeting.
2. Computer Vision and Image Analysis of Art. Multispectral imaging from X-ray to IR figure here for attribution analysis and dating, reverse fading to recover original colours and predicting colour changes due to conservation treatment.
3. Image Quality and System Performance. This covers a wide spectrum from marketing to security, from traditional to digital print over the whole imaging chain; capture, processing to output. Readability of electronic paper and image measurement could be interesting topics too. They also hope for a whole section on image quality standards. Peter Burns, Robin Jenkin, Lindsay MacDonald and Sophie Triantaphillidou are all on the organising committee so would be good points of contact for this meeting.
4. Digital Photography. Again looks to cover the whole imaging chain through lens systems and characterisation, IR and UV aliasing filters, multispectral imaging, printing and product and archival photography.
Given some time I would also like to look in on the following.
5. Medical Forensics and Security. Looks at secure technologies for multimedia creation, distribution, use and forensics.
6. Visualization and data analysis. Internet, web and security visualisations look interesting.
7. Sensors, cameras and systems for Industrial / Scientific applications. There looks to be some really interesting sensor stuff here, covering CCD and CMOS from the UV out to IR.
8. A new conference entitled Imaging and Printing in a Web 2.0 World. Workflow for web-to-print applications looks interesting.
Look forward to seeing you there!