**5.1 Noise in SAR imagery**

A proportionality relation exists between Speckle noise and the wavelet coefficients . Since Speckle is approached as a multiplicative noise, this contribution will be larger for higher reflectivity regions. It is also known that speckle in SAR images is spatially correlated. That is to say the noise is colored. Therefore its behavior in the Fourier domain is such that there is a peak of a given width around the zero frequency. This is readily observed as a wavelet coefficient variance plateau when decomposing a correlated noise model on a wavelet basis. As decomposition gets to scales larger than the correlation length, the contribution from speckle decreases linearly.
