4.3 Looking at X-rays
Select the ‘Look at X-rays’ button, click on ‘enable dynamics’, and press the ‘new X-ray’ button to import an X-ray file in the .tif format. For example, when selecting the X-ray for The Milkmaid, L07.tif, the interface appears as in figure .
This shows the full X-ray on the left, and a zoomed in portion (with default size 2 square cm) on the right. This can be used to examine the digital X-ray and select interesting areas for further investigation. If desired, the selected region can be saved to disk (using the ‘save’ button) which automatically documents the image file and the location of the zoomed in portion in the file name so that any given feature can be easily found again. The zoomed area, indicated by the small green box, can be moved by dragging with the mouse, and the size of the box can be adjusted with the two sliders. If desired, the X-ray can be inverted (using the positive/negative checkbox) and/or the contrast enhanced (using the contrast checkbox).
A crude manual thread count can be made by selecting the ‘show grid’ checkbox. This will partition the zoomed image into 0.5 cm square blocks, and it is pretty straightforward to then count the number of threads that pass within two (or more) of the gridded blocks. By scanning around the image and taking a handful of such thread counts, it is straightforward to get an idea of the approximate counts in the vertical and horizontal directions. Although quicker, this kind of count shares some problems with traditional hand counts: they are approximate and there is no easy way to document the exact locations and values of the counts, that is, they are not easily repeatable.
The interface for the ‘Look at X-rays’ function shows the complete X-ray on the left and zooms into a 2 square cm patch located at the position of the green box (shown over the right eye of the woman). Moving the box scans the patch and locates places of interest within the X-ray. The ‘show grid’ function allows for quick thread counts.