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sparse image representation via combined transforms - Convex ...

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A.3 Edgelet transform of the wood grain <strong>image</strong>: (a) is the original; (d) is the<br />

sorted coefficients; (b), (c), (e) and (f) are reconstructions based on the<br />

largest 1 × 10 4 ,2× 10 4 ,4× 10 4 ,8× 10 4 coefficients, respectively. . . . . . . 140<br />

A.4 Edgelet transform of Lenna <strong>image</strong>: (a) is the original Lenna <strong>image</strong>; (b) is the<br />

filtered version; (c) is the sorted largest 5, 000 coefficients out of 428032. (d),<br />

(e) and (f) are the reconstructions based on the largest 1000, 2000 and 4000<br />

coefficients, respectively. . . . .......................... 141<br />

A.5 Vertices at scale j, fora8× 8 <strong>image</strong> with l = 1. The arrows shows the trend<br />

of ordering. Integers outside are the labels of vertices. . . .......... 144<br />

A.6 Weights of pixels for one edgelet coefficient. .................. 147<br />

B.1 X-interpolation................................... 156<br />

B.2 Effectiveregion. ................................. 162<br />

B.3 Basic elements of the fast edgelet-like transform. . .............. 163<br />

B.4 Multiscale fast edgelet-like transform of artificial needle-like <strong>image</strong>s. . . . . 164<br />

B.5 Fast edgelet-like transform of wood grain <strong>image</strong>. . .............. 165<br />

B.6 Fast edgelet-like transform of wood grain <strong>image</strong>. . .............. 166<br />

B.7 Sinc function in (a) and its Fourier transform—blocky function in (b). . . . 167<br />

B.8 Raised cosine function in (b) and its counterpart in time domain in (a). . . 168<br />

B.9 Fifty percent tapered window function in (b) and its counterpart in time<br />

domain in (a). . . . . . .............................. 169<br />

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