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![[Figure 4]](mo5116fig4mag.jpg)
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Figure 4
Cropped and magnified PCXI reference images of six different materials used as a paper analyzer: (a) sandpaper of 15.3 µm feature size, (b) sandpaper of 40.5 µm feature size, (c) sandpaper of 82 µm feature size, (d) sandpaper of 201 µm feature size, (e) paper towel used as an analyzer, (f) Reflex Ultra White A4 Paper used as an analyzer. The sample-to-detector distance was set at 75 cm. The visibility (calculated using Michelson's definition, after eliminating outliers, that is those pixels occupying a gray level outside the central histogram peak, with the central peak edges defined as where the number of pixels of that gray level falls below 5 in the 2560 × 2160 image) for panels (a)–(f) are 0.93, 0.97, 0.95, 0.96, 0.88 and 0.82, respectively. Measuring visibility using a profile across the image (as performed with regular grid patterns) gives a visibility of 0.55–0.60 for the sandpapers and 0.35–0.40 for the tissue papers. A linear grayscale from 400 to 19000 is used for images (a)–(d), and from 4000 to 11000 for images (e) and (f). |
![[Figure 4]](mo5116fig4.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
