Better Detail than with the Naked Eye
A Preservation Digital Object (PDO) provides extraordinary detail. The resolution and ease of magnification in a digital viewer allows easy holistic examination of an object, from the full view of even a very large object to a small feature. It is not uncommon for this to result in a viewing experience that exceeds the quality of an in-person examination.
“There are things that the camera can see that the eye can’t see. Often, when I’m photographing objects and working with the conservation team, we’ll see things that they didn’t realize were happening.”
– Graham Haber, Photographer, The Morgan Library & Museum
Better Methods of Examination, Search & Comparison
Using a PDO allows side-by-side comparison between different areas of one object or of two different objects, without being limited by the sizes or locations of the original physical objects. Such comparisons are essentially impossible with physical objects without violating preservation handling protocols. Consider an analysis of three Van Gogh paintings held at three institutions in three different continents. By placing the three PDOs at any desired magnification or area of interest next to each other on one screen the brush strokes and color palettes can be compared. Such options may seem trivially obvious, but sadly, many institutions have not followed the strict preservation-grade image quality guidelines required to make such direct comparisons meaningful. Color, tone, and texture can only be compared between three separately digitized paintings if each institution digitized their collection within preservation-level tolerances. This requires at least FADGI 4-Star or METAMORFOZE-Strict image quality [see FADGI and METAMOROFOZE], which few digitization systems can achieve, in practice. Moreover PDOs can be manually transcribed or run through OCR software to allow text searches and statistics.
“One of our work streams is called ‘Do-it-Yourself History’ where we put the captured image up on the web for the public to transcribe which we can then OCR. In addition to being able to view material online, the OCR work allows people to search by keyword, giving even greater access to our material than if a researcher just worked with the original material.”
– Nancy Kraft, Preservation Librarian, University of Iowa Libraries
Similar challenges are posed by collections that are so large, or are under such stringent handling protocols, that the physical handling of the original materials obscures their wholistic meaning as a collection. In such a case, researching using a set of Preservation Digital Objects can provide a different understanding of the collection as a whole than physically handling the individual originals.
“There are times when there are so many of something, a negative, a group of prints, pages in a manuscript, that handling the physical objects can be overwhelming and sometimes impossible. But the process of digitization allows you to control, to organize, to move through that material in an efficient and organized way. So the digitization can allow a type of access that the physical objects prevent.
[One example of this is the “Big Book”.] W. Eugene Smith towards the end of his life wanted to create a Magnum Opus, a publication that would capture his life’s work and bring together images from all kinds of different projects. So he created a book maquette, which is frequently referred to as the “Big Book”. We have that original maquette here at the Center for Creative Photography, but it’s very fragile and it’s very light sensitive. So when you handle that original object you have to do it with tremendous care. In fact, the fragility of it makes the process of looking at it very awkward, very uncomfortable. So we were able to digitize the “Big Book” and create a facsimile which allows you to move through it with a flow and a speed that allows you to begin to see the way that he was thinking about the sequencing and bringing together of images. Only through the digitization process were we able to get a good understanding of his original intent, even though we have the original maquette”
– Becky Senf, Norton Family Curator, Center for Creative Photography
Textural and Contrast Enhancement, Otherwise Not Possible
PDOs allow enhancement to the viewing of the subject matter in ways that are not possible when viewing the physical original. Material which is faded can be viewed under strongly increased contrast, increasing legibility in some cases and providing for the discovery of content otherwise entirely obscured in other cases. The hue contrast of subtle variations of color can be increased making small differences easy to identify. With some objects, raking illumination brings forward textural detail and dimensional features which are barely or not at all visible in even illumination. However, viewing the physical object under such raking light is highly problematic, as the light will always fall off across the object (the parts of the object that are further from the light will be less brightly illuminated). Using Capture One CH Edition, light fall-off can be mapped and completely corrected, allowing the textural enhancement of raking asymmetrical lighting without the expected loss of tonal consistency across the object.
Digitization allows capture outside of the visible spectrum. This can be used to shoot through overpainting, or to reveal the content in damaged/burned/moldy areas of an object. Multispectral capture requires specialized versions of capture equipment such as the DT Multispectra Camera, which can image in both infrared and UV spectra.
Comparison over Time
In many areas of research and conservation, it is important to track changes to an object over time. If an institution follows preservation-quality guidelines and includes an object level target [see Object Level Target (OLT)], an object can be imaged at different times and compared. The tight tolerances and practical verification allow for even very small changes to be detected. This also requires at least FADGI 4-Star or METAMORFOZE image quality, a guideline few digitization systems can achieve in practice.