Digital Signal Processing Reference
In-Depth Information
DWT approximation. Fig. 14-3(a) and 14-3(b) show the similarity. The
diagonal DWT detail corresponds to the diagonal directional difference
image. In this case, first we take a horizontal directional difference and then
for the resulting result we take a vertical difference. Fig. 14-4(a) and 14-4(b)
show the relation between these two images.
Figure 14-3.
(a) Difference image (Vertical), (b) Horizontal DWT-detail
Figure 14-4.
(a) Difference image (Diagonal direction), (b) Diagonal DWT-detail
3.2
Reconstruction
As described above each directional difference image is very similar to
the corresponding detail. Actually replacing these DWT details by the
corresponding differences we get Fig. 14-5 through the inverse DWT. The
SNR of Fig. 14-5(a) is 27.3 dB. And that of Fig. 14-5(b) is 28.5 dB.
In this case it is better to take edge enhancement of the DWT-
approximation image. There are many cases such a picture quality as that of
