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Jonathan Ben-Dov
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Asaf Gayer
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Eshbal Ratzon
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In order to produce a canvas – a visual file with images of all fragments of a given scroll pasted on it together with the text – scholars need to draw on images of scrolls from various sources. Retaining the correct proportion of the fragments throughout the different stages of this procedure is crucial, while every stage in the procedure creates its own unique challenges. The scaling problems that arise from this complex procedure require a prudent methodology, which is delineated in this chapter.

In the case of the DSS, a scholar is most likely to use the PAM images and the new images from the LLDSSDL. The PAM images present the fragments on plates next to a hand-drawn ruler. These plates were then placed on a photography table, with the camera fixed above at a distance, using a device to hold it still. Until 1954–1955, the photographer, Najib Anton Albina, used to pick the exact place for the camera according to the focusing needs of each photo, while at a later stage he fixed the camera at a constant distance (figure 4).1

Figure 4
Figure 4

Najib Anton Albina photographing scroll fragments in the 1950s (PAM 43.887)

© IAA, LLDSSDL, Photographer: Unknown. https://www.deadseascrolls.org.il/learn-about-the-scrolls/conservation

The result is that various PAM plates present the fragments on different scales, thus fragments taken from two different plates cannot be assumed to align. Furthermore, the IAA recently scanned the negatives of the PAM images and uploaded most of them to the LLDSSDL website. The entire process of photographing and digitalization of the PAM images thus includes several variables that influence their scaling.

Measuring the scale on a sample of digitized PAM images may help scholars in their analysis of these variables. The table below includes data about a number of a randomly chosen PAM images from the series 40–43: the length of a measure of 1 cm on the scale, measured digitally; the ruler number – each hand drawn ruler was given a random number in order to allow us to follow the change of rulers on the PAM plates;2 the date that the photograph was taken;3 the orientation of the plate; and the location of the ruler on the plate.

Table 1
Table 1

Scaling of PAM plates in relation to features of their rulers

For most PAM images taken since 1954, 1 cm on the scale measures approximately 0.55 cm. As mentioned, the fact that the rulers were hand-drawn creates variations in their accuracy. The table demonstrates that slight variations between the measured length of 1 cm on the ruler are indeed correlated to the use of different rulers. In some cases, a significant difference occurs, where 1 cm measures as little as 0.37 (PAM 41.139, 42.041, 42.042) or as much as 0.61 mm (PAM 42.034). This discrepancy may be explained either by assuming that Albina chose to change the camera setting for some reason, or by imbuing the changes of scaling through the procedure of saving, compression, and transmission of these specific digital files. Prior to 1954 we find that 1 cm on the ruler is variously represented in the images. As can be seen from the data in the table, the orientation of the plate itself (horizontal or vertical) and the exact place of the ruler may slightly influence the scaling of the image due to the different angle that the light reflects from the ruler to the camera.

In theory, it would be sufficient to measure the ruler and then rescale the image accordingly to make it fit reality on a 1:1 scale. This can be easily done using an image manipulation program. Such a procedure solves the inconsistencies that are due to the distance of the camera from the plate and the file conversion, but it does not solve the more fundamental problems created by the fact that rulers are hand-drawn and variously placed on the plates with unknown accuracy. Due to this problem, comparing different images of the same fragment reveals as much as a 10–15% difference in size, even after a digital process of re-scaling that verifies that 1 cm on the ruler measures 1 cm on the software.

This problem can be solved by using the new LLDSSDL images as a scaling anchor, to which all the previous images of a given fragment can be compared and scaled accordingly. Unlike the photos taken in the Rockefeller Museum, the conditions in the IAA lab follow a strict protocol, and a standard commercial ruler (i.e., not hand-drawn) appears in each of the photos. The camera at the IAA lab is static and constant, and so is the position of the imaged fragments. However, it is important to note that the scaling may be disturbed during the transmission of the image files between the IAA laboratory and the scholars’ computers. One should therefore also affirm the scaling of the LLDSSDL images. This can be done by measuring the ruler, and, if needed, rescaling the image accordingly using the same process described below for the PAM images. As explained in chapter 2, in order to maintain the relative errors to a minimum, it is advised to measure the entire length of the ruler on the image rather than only an inch or a centimeter.

When producing material reconstructions, using the PAM images is often preferable over the newer LLDSSDL images. While the latter give a better view of the extant letters, they reflect a later and often shrunk and deteriorated stage of material preservation.

Here are the recommended steps for scaling, focusing on the adaptation of PAM images to the new IAA images:4

  1. Place both the PAM image and the LLDSSDL image as two separate layers in the same file, with the PAM image as the upper layer.

  2. Diminish the opacity to make the PAM image semi-transparent.

  3. Make sure that the height and width of all layers are bonded to maintain their ratio.

  4. Adapt the scaling of the PAM image according to the new IAA image. Prominent ink marks and spacing between lines should act as control points. The more control points checked, the more accurate the scaling is.

  5. Note: the fragments may have shrunk or deteriorated during the time between the taking of the two images. It is important to find an area on the fragment that remained unchanged and adapt the scaling based on that area. It is sometimes best to use both color and IR images for this process, since both the ink and the color of the skin are important for evaluating the changes the fragment went through.

Since copying or exporting images between files and software may affect the scaling, it is crucial to verify the scaling of all the images when used on a different file or software.

In conclusion, scaling is mainly a problem for the old PAM images, to which only hand-drawn rulers are attached, but it is important to check if any damage has also occurred to the new IAA images during the process of file transmission. When only PAM images are available for a certain fragment, an error of 10–15% may occur even after a rescaling of the image. But in most cases when an IAA image exists, comparing it with the PAM image using the above protocol makes the scaling error negligible. After all images are properly scaled, they are prepared for the digital canvas in order to begin the reconstruction of the scroll.

1

Strugnell, “On the History of the Photographing,” 125–31.

2

In the current sample of PAM plates nine different rulers were found.

3

Tov and Pfann, Companion Volume, 155–62.

4

The questions of scaling were previously discussed by Zuckerman, Levy, and Lundberg as part of their methodology for stacking images of the same fragment as digital layers in Photoshop, yet they do not list concrete steps for scaling. See Zuckerman, “The Dynamics of Change,” 69–88. See pages 3–4 in the online version: https://dornsife.usc.edu/wsrp/dynamics-of-change/; and in more length Zuckerman et al., “A Methodology for the Digital Reconstruction,” 45–48.

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