Figure 5.

(a) and (e) High resolution raw image after pixel SR with circular averaging and its low-pass filtered version, respectively. (b) and (f) Both the original and the low-pass filtered raw frames are back propagated over a small depth neighborhood (e.g., ±20 μm) around the optimal reconstruction height (z₂^*) and the corresponding phase images are extracted. The reconstructions corresponding to the low-pass filtered images only contain features from the background. (c) Each original phase reconstruction from the stack in (b) is element-wise divided by its low-pass filtered phase reconstruction from the same height in (f), after adding 2π radians to each image. The resulting image stack is a background compensated version of (b), only containing higher frequency noise grains. (d) Averaging the background compensated stack in (c) further suppresses the noise grains.