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![[Figure 7]](mo5116fig7mag.jpg)
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Figure 7
Differential shift images: (a) Sy(x, y) with the average of 20 images at 0.5 ms exposure used for analysis, and (b) Sy(x, y) with a single image at 0.5 ms exposure used for analysis. The differential shift image obtained using the average of 20 images, as shown in (a), fails to detect the vertical gradient across the spheres because of a stationary and structured dark current, resulting in the visibly uniform gray appearance. In spite of the high-frequency noise seen in (b), the differential shift image obtained using a single image shows the change in gradient across the spheres. When these images are integrated to give the total thickness, (b) gives a considerably more accurate reconstruction. Our best differential phase reconstruction at 0.5 ms is shown in (c), which was reconstructed using a single sample-and-reference image with only high-frequency noise filtering, to a 20-image-averaged reference speckle image with both dark-current subtraction and high-frequency noise filtering. |
![[Figure 7]](mo5116fig7.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
