max.m

多小波图像压缩处理

function [Smax,Imax] = max(S,varargin)


if ~isnumeric(S)
    n = size(S);
    S = reshape(simplify(S(:)),n);
end

if issymbolic(S)
    error('MAX is not defined for symbolic variables');
end

n = size(S);
switch nargin
 case 2
% Smax = max(S,T)
  T = varargin{1};
  if ~isnumeric(T)
      m = size(T);
      T = reshape(simplify(T(:)),m);
  end
  if issymbolic(T)
      error('MAX is not defined for symbolic variables');
  end
  m = size(T);
  if (prod(m) == 1)
% T is scalar
      DS = double(S(:));
      DT = double(T);
      Smax = S(:);
      for i = 1:length(Smax)
	  if (DS(i) < DT)
	      Smax(i) = T;
	  end
	  Smax = reshape(Smax,n);
      end
      return
  elseif (prod(n) == 1)	  
% S is scalar
      DS = double(S);
      DT = double(T(:));
      Smax = T(:);
      for i = 1:length(Smax)
	  if (DT(i) < DS)
	      Smax(i) = S;
	  end
	  Smax = reshape(Smax,m);
      end
      return
  else
% both are matrices
      if (length(m) ~= length(n))
	  error('dimensions must agree');
      end
      if ~iszero(m-n)
	  error('dimensions must agree');
      end	  
      DS = double(S(:));
      DT = double(T(:));
      Smax = S(:);
      for i = 1:length(Smax)
	  if (DS(i) < DT(i))
	      Smax(i) = T(i);
	  end
	  Smax = reshape(Smax,n);
      end
      return
  end

 case {1,3}
  if (nargin == 1)
      lnd = 1; % leading nonzero dimension
      for i = 2:length(n)
	  if (n(lnd) == 1 & n(i) > 1)
	      lnd = i;
	  end
      end
  else
      lnd = varargin{2};
  end
  D = reshape(double(S(:)),n);
  [Dmax,Imax] = max(D,[],lnd);
  nn = [n(1:lnd-1),1,n(lnd+1:end)];
  Smax = sym(zeros(size(Dmax)));
  for i = 1:prod(nn)
      ind = index(nn,i);
      Smax(ind{:}) = S(ind{1:lnd-1},Imax(ind{:}),ind{lnd+1:end});
  end
end