The name is absent

xii

4.2 (a) White-light image of object mask shaped as the Chinese character
’’light”. Terahertz images reconstructed via compressed sensing using
(b) 300 and (c) 600 magnitude measurements, which are respectively
about 30% and 60% of the total number of image pixels. Both figures
display a 32 × 32 image and the pixel size is Imm × Imm....... 35

4.3 As the number of measurements (M) used in CS increases, the
mean-squared error (MSE) between the magnitudes of the
reconstructed image and the reference image for the object in
Figure 4.2, normalized by the squared energy of the reference image,
decreases. The MSE decay is fast from 50 to IOO CS measurements.
After the number of CS measurements exceeds the “sparsity” of the
object, the decay Hattens out....................... 36

4.4 Compressed sensing reconstructions of (a) the image amplitude and

(b) the phase, using 400 (complex) measurements. Here, the object is
a rectangular hole in an opaque screen, covered with a (transparent)
plastic plate. The plate covering the upper half of the hole is thicker
than the lower half. The reconstructed phase image exhibits this
contrast much better than the amplitude image............. 37

4.5 The estimated thickness of the plastic plate, versus number of
measurements (n) used in CS reconstruction for the object in
Figure 4.4. Dashed line indicates the actual thickness difference (1.73
mm), as determined using a micrometer. The thickness estimates
rapidly converge to the correct answer with increasing n........ 38

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