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Diffstat (limited to 'SD-VBS/benchmarks/texture_synthesis/src/matlab/modskew.m')
| -rwxr-xr-x | SD-VBS/benchmarks/texture_synthesis/src/matlab/modskew.m | 183 |
1 files changed, 0 insertions, 183 deletions
diff --git a/SD-VBS/benchmarks/texture_synthesis/src/matlab/modskew.m b/SD-VBS/benchmarks/texture_synthesis/src/matlab/modskew.m deleted file mode 100755 index 3de0e3c..0000000 --- a/SD-VBS/benchmarks/texture_synthesis/src/matlab/modskew.m +++ /dev/null | |||
| @@ -1,183 +0,0 @@ | |||
| 1 | function [chm, snrk] = modskew(ch,sk,p); | ||
| 2 | |||
| 3 | % Adjust the sample skewness of a vector/matrix, using gradient projection, | ||
| 4 | % without affecting its sample mean and variance. | ||
| 5 | % | ||
| 6 | % This operation is not an orthogonal projection, but the projection angle is | ||
| 7 | % near pi/2 when sk is close to the original skewness, which is a realistic | ||
| 8 | % assumption when doing iterative projections in a pyramid, for example | ||
| 9 | % (small corrections to the channels' statistics). | ||
| 10 | % | ||
| 11 | % [xm, snrk] = modskew(x,sk,p); | ||
| 12 | % sk: new skweness | ||
| 13 | % p [OPTIONAL]: mixing proportion between sk0 and sk | ||
| 14 | % it imposes (1-p)*sk0 + p*sk, | ||
| 15 | % being sk0 the current skewness. | ||
| 16 | % DEFAULT: p = 1; | ||
| 17 | |||
| 18 | % | ||
| 19 | % JPM. 2/98, IODV, CSIC | ||
| 20 | % 4/00, CNS, NYU | ||
| 21 | |||
| 22 | Warn = 0; % Set to 1 if you want to see warning messages | ||
| 23 | if ~exist('p'), | ||
| 24 | p = 1; | ||
| 25 | end | ||
| 26 | |||
| 27 | N=prod(size(ch)); % number of samples | ||
| 28 | me=mean2(ch); | ||
| 29 | ch=ch-me; | ||
| 30 | |||
| 31 | for n=2:6, | ||
| 32 | m(n)=mean2(ch.^n); | ||
| 33 | end | ||
| 34 | |||
| 35 | sd=sqrt(m(2)); % standard deviation | ||
| 36 | s=m(3)/sd^3; % original skewness | ||
| 37 | snrk = snr(sk, sk-s); | ||
| 38 | sk = s*(1-p) + sk*p; | ||
| 39 | |||
| 40 | % Define the coefficients of the numerator (A*lam^3+B*lam^2+C*lam+D) | ||
| 41 | |||
| 42 | A=m(6)-3*sd*s*m(5)+3*sd^2*(s^2-1)*m(4)+sd^6*(2+3*s^2-s^4); | ||
| 43 | B=3*(m(5)-2*sd*s*m(4)+sd^5*s^3); | ||
| 44 | C=3*(m(4)-sd^4*(1+s^2)); | ||
| 45 | D=s*sd^3; | ||
| 46 | |||
| 47 | a(7)=A^2; | ||
| 48 | a(6)=2*A*B; | ||
| 49 | a(5)=B^2+2*A*C; | ||
| 50 | a(4)=2*(A*D+B*C); | ||
| 51 | a(3)=C^2+2*B*D; | ||
| 52 | a(2)=2*C*D; | ||
| 53 | a(1)=D^2; | ||
| 54 | |||
| 55 | % Define the coefficients of the denominator (A2+B2*lam^2) | ||
| 56 | |||
| 57 | A2=sd^2; | ||
| 58 | B2=m(4)-(1+s^2)*sd^4; | ||
| 59 | |||
| 60 | b=zeros(1,7); | ||
| 61 | b(7)=B2^3; | ||
| 62 | b(5)=3*A2*B2^2; | ||
| 63 | b(3)=3*A2^2*B2; | ||
| 64 | b(1)=A2^3; | ||
| 65 | |||
| 66 | |||
| 67 | if 0, % test | ||
| 68 | |||
| 69 | lam = -2:0.02:2; | ||
| 70 | S = (A*lam.^3+B*lam.^2+C*lam+D)./... | ||
| 71 | sqrt(b(7)*lam.^6 + b(5)*lam.^4 + b(3)*lam.^2 + b(1)); | ||
| 72 | % grd = ch.^2 - m(2) - sd * s * ch; | ||
| 73 | % for lam = -1:0.01:1, | ||
| 74 | % n = lam*100+101; | ||
| 75 | % chp = ch + lam*grd; | ||
| 76 | % S2(n) = mean2(chp.^3)/abs(mean2(chp.^2))^(1.5); | ||
| 77 | % end | ||
| 78 | lam = -2:0.02:2; | ||
| 79 | figure(1);plot(lam,S);grid;drawnow | ||
| 80 | % snr(S2, S-S2) | ||
| 81 | |||
| 82 | end % test | ||
| 83 | |||
| 84 | % Now I compute its derivative with respect to lambda | ||
| 85 | |||
| 86 | d(8) = B*b(7); | ||
| 87 | d(7) = 2*C*b(7) - A*b(5); | ||
| 88 | d(6) = 3*D*b(7); | ||
| 89 | d(5) = C*b(5) - 2*A*b(3); | ||
| 90 | d(4) = 2*D*b(5) - B*b(3); | ||
| 91 | d(3) = -3*A*b(1); | ||
| 92 | d(2) = D*b(3) - 2*B*b(1); | ||
| 93 | d(1) = -C*b(1); | ||
| 94 | |||
| 95 | d = d(8:-1:1); | ||
| 96 | mMlambda = roots(d); | ||
| 97 | |||
| 98 | tg = imag(mMlambda)./real(mMlambda); | ||
| 99 | mMlambda = real(mMlambda(find(abs(tg)<1e-6))); | ||
| 100 | lNeg = mMlambda(find(mMlambda<0)); | ||
| 101 | if length(lNeg)==0, | ||
| 102 | lNeg = -1/eps; | ||
| 103 | end | ||
| 104 | lPos = mMlambda(find(mMlambda>=0)); | ||
| 105 | if length(lPos)==0, | ||
| 106 | lPos = 1/eps; | ||
| 107 | end | ||
| 108 | lmi = max(lNeg); | ||
| 109 | lma = min(lPos); | ||
| 110 | |||
| 111 | lam = [lmi lma]; | ||
| 112 | mMnewSt = polyval([A B C D],lam)./(polyval(b(7:-1:1),lam)).^0.5; | ||
| 113 | skmin = min(mMnewSt); | ||
| 114 | skmax = max(mMnewSt); | ||
| 115 | |||
| 116 | |||
| 117 | % Given a desired skewness, solves for lambda | ||
| 118 | |||
| 119 | if sk<=skmin & Warn, | ||
| 120 | lam = lmi; | ||
| 121 | warning('Saturating (down) skewness!'); | ||
| 122 | skmin | ||
| 123 | elseif sk>=skmax & Warn, | ||
| 124 | lam = lma; | ||
| 125 | warning('Saturating (up) skewness!'); | ||
| 126 | skmax | ||
| 127 | else | ||
| 128 | |||
| 129 | |||
| 130 | % The equation is sum(c.*lam.^(0:6))=0 | ||
| 131 | |||
| 132 | c=a-b*sk^2; | ||
| 133 | |||
| 134 | c=c(7:-1:1); | ||
| 135 | |||
| 136 | r=roots(c); | ||
| 137 | |||
| 138 | % Chose the real solution with minimum absolute value with the rigth sign | ||
| 139 | lam=-Inf; | ||
| 140 | co=0; | ||
| 141 | for n=1:6, | ||
| 142 | tg = imag(r(n))/real(r(n)); | ||
| 143 | if (abs(tg)<1e-6)&(sign(real(r(n)))==sign(sk-s)), | ||
| 144 | co=co+1; | ||
| 145 | lam(co)=real(r(n)); | ||
| 146 | end | ||
| 147 | end | ||
| 148 | if min(abs(lam))==Inf & Warn, | ||
| 149 | display('Warning: Skew adjustment skipped!'); | ||
| 150 | lam=0; | ||
| 151 | end | ||
| 152 | |||
| 153 | p=[A B C D]; | ||
| 154 | |||
| 155 | if length(lam)>1, | ||
| 156 | foo=sign(polyval(p,lam)); | ||
| 157 | if any(foo==0), | ||
| 158 | lam = lam(find(foo==0)); | ||
| 159 | else | ||
| 160 | lam = lam(find(foo==sign(sk))); % rejects the symmetric solution | ||
| 161 | end | ||
| 162 | if length(lam)>0, | ||
| 163 | lam=lam(find(abs(lam)==min(abs(lam)))); % the smallest that fix the skew | ||
| 164 | lam=lam(1); | ||
| 165 | else | ||
| 166 | lam = 0; | ||
| 167 | end | ||
| 168 | end | ||
| 169 | end % if else | ||
| 170 | |||
| 171 | % Modify the channel | ||
| 172 | chm=ch+lam*(ch.^2-sd^2-sd*s*ch); % adjust the skewness | ||
| 173 | chm=chm*sqrt(m(2)/mean2(chm.^2)); % adjust the variance | ||
| 174 | chm=chm+me; % adjust the mean | ||
| 175 | % (These don't affect the skewness) | ||
| 176 | % Check the result | ||
| 177 | %mem=mean2(chm); | ||
| 178 | %sk2=mean2((chm-mem).^3)/mean2((chm-mem).^2).^(3/2); | ||
| 179 | %sk - sk2 | ||
| 180 | %SNR=snr(sk,sk-sk2) | ||
| 181 | |||
| 182 | |||
| 183 | |||
