去雾算法matlab何凯明

function Y = vanherk(X,N,TYPE,varargin) % VANHERK Fast max/min 1D filter % % Y = VANHERK(X,N,TYPE) performs the 1D max/min filtering of the row % vector X using a N-length filter. % The filtering type is defined by TYPE = 'max' or 'min'. This function % uses the van Herk algorithm for min/max filters that demands only 3 % min/max calculations per element, independently of the filter size. % % If X is a 2D matrix, each row will be filtered separately. % % Y = VANHERK(...,'col') performs the filtering on the columns of X. % % Y = VANHERK(...,'shape') returns the subset of the filtering specified % by 'shape' : % 'full' - Returns the full filtering result, % 'same' - (default) Returns the central filter area that is the % same size as X, % 'valid' - Returns only the area where no filter elements are outside % the image. % % X can be uint8 or double. If X is uint8 the processing is quite faster, so % dont't use X as double, unless it is really necessary. % % Initialization [direc, shape] = parse_inputs(varargin{:}); if strcmp(direc,'col') X = X'; end if strcmp(TYPE,'max') maxfilt = 1; elseif strcmp(TYPE,'min') maxfilt = 0; else error([ 'TYPE must be ' char(39) 'max' char(39) ' or ' char(39) 'min' char(39) '.']) end % Correcting X size fixsize = 0; addel = 0; if mod(size(X,2),N) ~= 0 fixsize = 1; addel = N-mod(size(X,2),N); if maxfilt f = [ X zeros(size(X,1), addel) ]; else f = [X repmat(X(:,end),1,addel)]; end else f = X; end lf = size(f,2); lx = size(X,2); clear X % Declaring aux. mat. g = f; h = g; % Filling g & h (aux. mat.) ig = 1:N:size(f,2); ih = ig + N - 1; g(:,ig) = f(:,ig); h(:,ih) = f(:,ih); if maxfilt for i = 2 : N igold = ig; ihold = ih; ig = ig + 1; ih = ih - 1; g(:,ig) = max(f(:,ig),g(:,igold)); h(:,ih) = max(f(:,ih),h(:,ihold)); end else for i = 2 : N igold = ig; ihold = ih; ig = ig + 1; ih = ih - 1; g(:,ig) = min(f(:,ig),g(:,igold)); h(:,ih) = min(f(:,ih),h(:,ihold)); end end clear f % Comparing g & h if strcmp(shape,'full') ig = [ N : 1 : lf ]; ih = [ 1 : 1 : lf-N+1 ]; if fixsize if maxfilt Y = [ g(:,1:N-1) max(g(:,ig), h(:,ih)) h(:,end-N+2:end-addel) ]; else Y = [ g(:,1:N-1) min(g(:,ig), h(:,ih)) h(:,end-N+2:end-addel) ]; end else if maxfilt Y = [ g(:,1:N-1) max(g(:,ig), h(:,ih)) h(:,end-N+2:end) ]; else Y = [ g(:,1:N-1) min(g(:,ig), h(:,ih)) h(:,end-N+2:end) ]; end end elseif strcmp(shape,'same') if fixsize if addel > (N-1)/2 disp('hoi') ig = [ N : 1 : lf - addel + floor((N-1)/2) ]; ih = [ 1 : 1 : lf-N+1 - addel + floor((N-1)/2)]; if maxfilt Y = [ g(:,1+ceil((N-1)/2):N-1) max(g(:,ig), h(:,ih)) ]; else Y = [ g(:,1+ceil((N-1)/2):N-1) min(g(:,ig), h(:,ih)) ]; end else ig = [ N : 1 : lf ]; ih = [ 1 : 1 : lf-N+1 ]; if maxfilt Y = [ g(:,1+ceil((N-1)/2):N-1) max(g(:,ig), h(:,ih)) h(:,lf-N+2:lf-N+1+floor((N-1)/2)-addel) ]; else Y = [ g(:,1+ceil((N-1)/2):N-1) min(g(:,ig), h(:,ih)) h(:,lf-N+2:lf-N+1+floor((N-1)/2)-addel) ]; end end else % not fixsize (addel=0, lf=lx) ig = [ N : 1 : lx ]; ih = [ 1 : 1 : lx-N+1 ]; if maxfilt Y = [ g(:,N-ceil((N-1)/2):N-1) max( g(:,ig), h(:,ih) ) h(:,lx-N+2:lx-N+1+floor((N-1)/2)) ]; else Y = [ g(:,N-ceil((N-1)/2):N-1) min( g(:,ig), h(:,ih) ) h(:,lx-N+2:lx-N+1+floor((N-1)/2)) ]; end end elseif strcmp(shape,'valid') ig = [ N : 1 : lx]; ih = [ 1 : 1: lx-N+1]; if maxfilt Y = [ max( g(:,ig), h(:,ih) ) ]; else Y = [ min( g(:,ig), h(:,ih) ) ]; end end if strcmp(direc,'col') Y = Y'; end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function [direc, shape] = parse_inputs(varargin) direc = 'lin'; shape = 'same'; flag = [0 0]; % [dir shape] for i = 1 : nargin t = varargin{i}; if strcmp(t,'col') & flag(1) == 0 direc = 'col'; flag(1) = 1; elseif strcmp(t,'full') & flag(2) == 0 shape = 'full'; flag(2) = 1; elseif strcmp(t,'same') & flag(2) == 0 shape = 'same'; flag(2) = 1; elseif strcmp(t,'valid') & flag(2) == 0 shape = 'valid'; flag(2) = 1; else error(['Too many / Unkown parameter : ' t ]) end end