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);