Fast digital lossy compression for X-ray ptychographic data

Huang, P.; Du, M.; Hammer, M.; Miceli, A.; Jacobsen, C.

doi:10.1107/S1600577520013326

Figure 7
Fourier ring correlation (FRC) curves for images reconstructed from simulated ptychography datasets with Poisson noise included. For each line color, the associated fluence n_ph in photons per pixel is indicated. The horizontal axis is shown as a fraction of the normalized spatial frequency $[u^{{\prime}}]$ of equation (10)

. Each curve is labeled with the fluence of averaged incident photons per pixel. Also shown on the plot is the 1/2-bit threshold curve, of which the crossing spatial frequency with the FRC curve is commonly used to define the achieved spatial resolution of the reconstructed image. The dependence of crossing in spatial frequency on fluence is shown in Fig. 8

. These curves are shown for the case of detector intensities recorded as-is (with no encoding) at upper left, and then for the lossy compression schemes (a), (b), and (c) in successive panels. The FRC is normally calculated from two separate instances of noisy data (van Heel, 1987

) which is the case labeled `independent noise' for schemes (a), (b), and (c), but we also show the case of comparison of a reconstruction from noisy data compared with the true object in the cases labeled `ground truth' for schemes (b) and (c). This is done because there is some spurious correlation with a scan grid artifact visible in the rise of the `independent noise' FRC curves at high spatial frequency for schemes (b) and (c).

JOURNAL OF
SYNCHROTRON
RADIATION

ISSN: 1600-5775

Volume 28| Part 1| January 2021| Pages 292-300

https://doi.org/10.1107/S1600577520013326

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