Mercurial > hg > smallbox
diff DL/two-step DL/dico_decorr_symetric.m @ 195:d50f5bdbe14c luisf_dev
- Added SMALL_DL_test: simple DL showcase
- Added dico_decorr_symmetric: improved version of INK-SVD decorrelation step
- Debugged SMALL_learn, SMALLBoxInit and SMALL_two_step_DL
author | Daniele Barchiesi <daniele.barchiesi@eecs.qmul.ac.uk> |
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date | Wed, 14 Mar 2012 14:42:52 +0000 |
parents | |
children | 69ce11724b1f |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/DL/two-step DL/dico_decorr_symetric.m Wed Mar 14 14:42:52 2012 +0000 @@ -0,0 +1,61 @@ +function dico = dico_decorr_symetric(dico, mu, amp) + %DICO_DECORR decorrelate a dictionary + % Parameters: + % dico: the dictionary + % mu: the coherence threshold + % amp: the amplitude coefficients, only used to decide which atom to + % project + % + % Result: + % dico: a dictionary close to the input one with coherence mu. + + eps = 1e-6; % define tolerance for normalisation term alpha + + % convert mu to the to the mean direction + theta = acos(mu)/2; + ctheta = cos(theta); + stheta = sin(theta); + + % compute atom weights + % if nargin > 2 + % rank = sum(amp.*amp, 2); + % else + % rank = randperm(length(dico)); + % end + + % several decorrelation iterations might be needed to reach global + % coherence mu. niter can be adjusted to needs. + niter = 1; + while max(max(abs(dico'*dico -eye(length(dico))))) > mu + 0.01 + % find pairs of high correlation atoms + colors = dico_color(dico, mu); + + % iterate on all pairs + nbColors = max(colors); + for c = 1:nbColors + index = find(colors==c); + if numel(index) == 2 + if dico(:,index(1))'*dico(:,index(2)) > 0 + %build the basis vectors + v1 = dico(:,index(1))+dico(:,index(2)); + v1 = v1/norm(v1); + v2 = dico(:,index(1))-dico(:,index(2)); + v2 = v2/norm(v2); + + dico(:,index(1)) = ctheta*v1+stheta*v2; + dico(:,index(2)) = ctheta*v1-stheta*v2; + else + v1 = dico(:,index(1))-dico(:,index(2)); + v1 = v1/norm(v1); + v2 = dico(:,index(1))+dico(:,index(2)); + v2 = v2/norm(v2); + + dico(:,index(1)) = ctheta*v1+stheta*v2; + dico(:,index(2)) = -ctheta*v1+stheta*v2; + end + end + end + niter = niter+1; + end +end +