双边滤波Matlab代码

%简单地说:

%A为给定图像，归一化到[,]的矩阵

%W为双边滤波器（核）的边长/

%定义域方差σd记为SIGMA(),值域方差σr记为SIGMA()

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Pre-process input and select appropriate filter.

function B = bfilter2(A,w,sigma)

% Verify that the input image exists and is valid.

if ~exist('A','var') || isempty(A)

   error('Input image A is undefined or invalid.');

end

if ~isfloat(A) || ~sum([,] == size(A,)) || ...

      min(A(:)) <  || max(A(:)) > 

   error(['Input image A must be a double precision ',...

          'matrix of size NxMx1 or NxMx3 on the closed ',...

          'interval [0,1].']);      

end

% Verify bilateral filter window size.

if ~exist('w','var') || isempty(w) || ...

      numel(w) ~=  || w < 

   w = ;

end

w = ceil(w);

% Verify bilateral filter standard deviations.

if ~exist('sigma','var') || isempty(sigma) || ...

      numel(sigma) ~=  || sigma() <=  || sigma() <= 

   sigma = [ 0.1];

end

% Apply either grayscale or color bilateral filtering.

if size(A,) == 

   B = bfltGray(A,w,sigma(),sigma());

else

   B = bfltColor(A,w,sigma(),sigma());

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Implements bilateral filtering for grayscale images.

function B = bfltGray(A,w,sigma_d,sigma_r)

% Pre-compute Gaussian distance weights.

[X,Y] = meshgrid(-w:w,-w:w);

%创建核距离矩阵，e.g.

%  [x,y]=meshgrid(-:,-:)

% 

% x =

% 

%     -          

%     -          

%     -          

% 

% 

% y =

% 

%     -    -    -

%                

%                

%计算定义域核

G = exp(-(X.^+Y.^)/(*sigma_d^));

% Create waitbar.

h = waitbar(,'Applying bilateral filter...');

set(h,'Name','Bilateral Filter Progress');

% Apply bilateral filter.

%计算值域核H 并与定义域核G 乘积得到双边权重函数F

dim = size(A);

B = zeros(dim);

for i = :dim()

   for j = :dim()

         % Extract local region.

         iMin = max(i-w,);

         iMax = min(i+w,dim());

         jMin = max(j-w,);

         jMax = min(j+w,dim());

         %定义当前核所作用的区域为(iMin:iMax,jMin:jMax)

         I = A(iMin:iMax,jMin:jMax);%提取该区域的源图像值赋给I

         % Compute Gaussian intensity weights.

         H = exp(-(I-A(i,j)).^/(*sigma_r^));

         % Calculate bilateral filter response.

         F = H.*G((iMin:iMax)-i+w+,(jMin:jMax)-j+w+);

         B(i,j) = sum(F(:).*I(:))/sum(F(:));

   end

   waitbar(i/dim());

end

% Close waitbar.

close(h);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Implements bilateral filter for color images.

function B = bfltColor(A,w,sigma_d,sigma_r)

% Convert input sRGB image to CIELab color space.

if exist('applycform','file')

   A = applycform(A,makecform('srgb2lab'));

else

   A = colorspace('Lab<-RGB',A);

end

% Pre-compute Gaussian domain weights.

[X,Y] = meshgrid(-w:w,-w:w);

G = exp(-(X.^+Y.^)/(*sigma_d^));

% Rescale range variance (using maximum luminance).

sigma_r = *sigma_r;

% Create waitbar.

h = waitbar(,'Applying bilateral filter...');

set(h,'Name','Bilateral Filter Progress');

% Apply bilateral filter.

dim = size(A);

B = zeros(dim);

for i = :dim()

   for j = :dim()

         % Extract local region.

         iMin = max(i-w,);

         iMax = min(i+w,dim());

         jMin = max(j-w,);

         jMax = min(j+w,dim());

         I = A(iMin:iMax,jMin:jMax,:);

         % Compute Gaussian range weights.

         dL = I(:,:,)-A(i,j,);

         da = I(:,:,)-A(i,j,);

         db = I(:,:,)-A(i,j,);

         H = exp(-(dL.^+da.^+db.^)/(*sigma_r^));

         % Calculate bilateral filter response.

         F = H.*G((iMin:iMax)-i+w+,(jMin:jMax)-j+w+);

         norm_F = sum(F(:));

         B(i,j,) = sum(sum(F.*I(:,:,)))/norm_F;

         B(i,j,) = sum(sum(F.*I(:,:,)))/norm_F;

         B(i,j,) = sum(sum(F.*I(:,:,)))/norm_F;

   end

   waitbar(i/dim());

end

% Convert filtered image back to sRGB color space.

if exist('applycform','file')

   B = applycform(B,makecform('lab2srgb'));

else  

   B = colorspace('RGB<-Lab',B);

end

% Close waitbar.

close(h);