Mercurial > hg > smallbox
diff util/sparco utils/pwsmoothfield.m @ 77:62f20b91d870
add routines from sparco problems privite folder to {root}\util
some changes to ksvd vs rlsdla image denoising example
| author | Ivan <ivan.damnjanovic@eecs.qmul.ac.uk> |
|---|---|
| date | Fri, 25 Mar 2011 14:01:50 +0000 |
| parents | |
| children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/util/sparco utils/pwsmoothfield.m Fri Mar 25 14:01:50 2011 +0000 @@ -0,0 +1,32 @@ +function f = pwsmoothfield(n,var,alpha) +% PWSMOOTHFIELD(N,VAR,ALPHA) +% Generate an image of piecewise smooth filtered white noise +% +% N = sidelength of the field in pixels +% VAR = variance of original white nose +% ALPHA = fraction of FFT coefficents to keep +% +% Returns an N-by-N array +% +% This file is used with the kind permission of Stephen J. Wright +% (swright@cs.wisc.edu), and was originally included in the GPSR +% v1.0 distribution: http://www.lx.it.pt/~mtf/GPSR . + +% $Id: pwsmoothfield.m 1040 2008-06-26 20:29:02Z ewout78 $ + +f = sqrt(var)*randn(n); +F = fft2(f); +a = ceil(n*alpha/2); +b = fix(n*(1-alpha)); +F(a+1:a+b,:) = 0; +F(:,a+1:a+b) = 0; +f = real(ifft2(F)); + +for i = 1:n + for j = 1:n + if (j/n >= 15*(i/n - 0.5)^3 + 0.4) + f(i,j) = f(i,j) + sqrt(var); + end + end +end +