%?ANISODIFF?-?Anisotropic?diffusion.
%
%?
%??diff?=?anisodiff（im?niter?kappa?lambda?option）
%
%?
%?????????im?????-?input?image
%?????????niter??-?number?of?iterations.
%?????????kappa??-?conduction?coefficient?20-100??
%?????????lambda?-?max?value?of?.25?for?stability
%?????????option?-?1?Perona?Malik?diffusion?equation?No?1
%??????????????????2?Perona?Malik?diffusion?equation?No?2
%
%?Return
%?????????diff???-?diffused?image.
%
%?kappa?controls?conduction?as?a?function?of?gradient.??If?kappa?is?low
%?then?mall?intensity?gradients?are?able?to?block?conduction?and?hence?diffusion
%?across?step?edges.??A?large?value?reduces?the?influence?of?intensity
%?gradients?on?conduction.
%
%?lambda?controls?speed?of?diffusion?（you?usually?want?it?at?a?maximum?of
%?0.25）
%
%?Diffusion?equation?1?preserve?high?contrast?edges?over?low?contrast?ones.
%?Diffusion?equation?2?favours?wide?regions?over?smaller?ones.

%?Reference:?
%?P.?Perona?and?J.?Malik.?
%?Scale-space?and?edge?detection?using?anisotropic?diffusion.
%?IEEE?Transactions?on?Pattern?Analysis?and?Machine?Intelligence?
%?12（7）:629-639?July?1990.


function?diff?=?anisodiff（im?niter?kappa?lambda?option）

if?ndims（im）==3
??error（‘Anisodiff?only?operates?on?2D?grey-scale?images‘）;
end

im?=?double（im）;
[rowscols]?=?size（im）;
diff?=?im;

%{
var?=?2;
x?=?（-4:4）;
g?=?exp（-x.*x/（2*var））;?g??=?g/sum（g）;

blurred?=?conv2（img‘same‘）;
im_b?=?conv2（blurredg‘‘same‘）;?

%}

for?i?=?1:niter
?%?fprintf（‘\rIteration?%d‘i）;

??%?Construct?diffl?which?is?the?same?as?diff?but
??%?has?an?extra?padding?of?zeros?around?it.
??diffl?=?zeros（rows+2?cols+2）;
??diffl（2:rows+1?2:cols+1）?=?diff;

??%?North?South?East?and?West?differences
??deltaN?=?diffl（1:rows2:cols+1）???-?diff;
??deltaS?=?diffl（3:rows+22:cols+1）?-?diff;
??deltaE?=?diffl（2:rows+13:cols+2）?-?diff;
??deltaW?=?diffl（2:rows+11:cols）???-?diff;
??%deltaN?=?diff;deltaW;
??

??%?Conduction

??if?option?==?1
????cN?=?exp（-（deltaN/kappa）.^2）;
????cS?=?exp（-（deltaS/kappa）.^2）;
????cE?=?exp（-（deltaE/kappa）.^2）;
????cW?=?exp（-（deltaW/kappa）.^2）;
??elseif?option?==?2
????cN?=?1./（1?+?（deltaN/kappa）.^2）;
????cS?=?1./（1?+?（deltaS/kappa）.^2）;
????cE?=?1./（1?+?（deltaE/kappa）.^2）;
????cW?=?1./（1?+?（deltaW/kappa）.^2）;
??end

??%?APPLYING?FOUR-POINT-TEMPLETE?FOR?numerical?solution?of?DIFFUSION?P.D.E.
??
??diff?=?diff?+?lambda*（cN.*deltaN?+?cS.*deltaS?+?cE.*deltaE?+?cW.*deltaW）;

%??Uncomment?the?following?to?see?a?progression?of?images
%??subplot（ceil（sqrt（niterations））ceil（sqrt（niterations））?i）
%??imagesc（diff）?colormap（gray）?axis?image

end
%fprintf（‘\n‘）;

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件?????1332481??2012-10-21?22:29??PM_AD\Scale-space?and?edge?detection?using?anisotropic?diffusion.pdf
?????文件????????2694??2006-02-13?15:32??PM_AD\anisodiff.m
?????目錄???????????0??2012-11-13?15:24??PM_AD\