小波变换及matlab源码

当调用wavefast函数发现matlab没有该函数，通过查阅找到了小波变换的m文件，保存成函数文件后就可以直接调用。

matlab源码：
(1) wave2gray.m

function w = wave2gray(c,  s,  scale,  border)  %WAVE2GRAY Display wavelet decomposition coefficients.  %   W = WAVE2GRAY(C, S, SCALE, BORDER) displays and returns a  %   wavelet coefficient image.  %       EXAMPLES:  %           wave2gray(c, s);                        Display w/defaults.  %           foo = wave2gray(c,   s);                Display and return.  %           foo = wave2gray(c,   s, 4);             Magnify the details.  %           foo = wave2gray(c,   s, -4);            Magnify absolute values.  %           foo = wave2gray(c,   s, 1, 'append');   Keep border values.  %  %       INPUTS/OUTPUTS:  %           [C, S] is a wavelet decomposition vector and bookkeeping  %           matrix.  %  %       SCALE               Detail coefficient scaling  %--------------------------------------------------------------------  %       0 or 1      Maximum range (default)  %       2, 3...     Magnify default by the scale factor  %       -1, -2...   Magnify absolute values by abs(scale)  %  %       BORDER          Border between wavelet decompositions  %--------------------------------------------------------------------  %       'absorb'        Border replaces image (default)  %       'append'        Border increases width of image  %  %       Image W:    ------- ------ -------------- -------------------  %                   |      |      |              |  %                   | a(n) | h(n) |              |  %                   |      |      |              |  %                   ------- ------     h(n-1)    |  %                   |      |      |              |  %                   | v(n) | d(n) |              |      h(n-2)  %                   |      |      |              |  %                   ------- ------ --------------  %                   |             |              |  %                   |    v(n-1)   |    d(n-1)    |  %                   |             |              |  %                   -------------- -------------- -------------------  %                   |                            |  %                   |           v(n-2)           |      d(n-2)  %                   |                            |  %  %       Here,  n denotes the decomposition step scale and a, h, v, d are  %       approximation,  horizontal,  vertical, and diagonal detail  %       coefficients,  respectively.  % Check input arguments for  reasonableness.  error(nargchk(2,   4,   nargin));  if (ndims(c) ~= 2)   |   (size(c, 1) ~= 1)      error('C must be a row vector.'); end  if (ndims(s) ~= 2)   | ~isreal(s)   | ~isnumeric(s)   |   (size(s, 2) ~= 2)      error('S must be a real, numeric two-column array.'); end  elements = prod(s, 2);  if (length(c) < elements(end))   |   ...          ~(elements(1) + 3 * sum(elements(2:end - 1)) >= elements(end))      error(['[C S] must be a standard wavelet ' ...                  'decomposition structure.']);  end  if (nargin > 2) & (~isreal(scale) | ~isnumeric(scale))      error('SCALE must be a real, numeric scalar.');  end  if (nargin > 3) & (~ischar(border))      error('BORDER must be character string.');  end  if  nargin == 2      scale =1;    % Default scale.  end  if nargin < 4      border = 'absorb'; % Default border.  end  % Scale coefficients and determine pad fill.  absflag = scale < 0;  scale = abs(scale);  if scale == 0      scale = 1;  end  [cd, w] = wavecut('a', c, s);  w = mat2gray(w);  cdx = max(abs(cd(:))) / scale;  if absflag      cd = mat2gray(abs(cd), [0, cdx]); fill = 0;  else      cd = mat2gray(cd, [-cdx, cdx]); fill = 0.5;  end  % Build gray image one decomposition at a time.  for i = size(s, 1) - 2:-1:1      ws = size(w);      h = wavecopy('h', cd, s, i);      pad = ws - size(h);    frontporch = round(pad / 2);      h = padarray(h, frontporch, fill, 'pre');      h = padarray(h, pad - frontporch, fill, 'post');      v = wavecopy('v',   cd,   s,   i);      pad = ws - size(v);            frontporch = round(pad  /  2);      v = padarray(v,   frontporch,   fill,   'pre');      v = padarray(v,  pad - frontporch,  fill,   'post');      d = wavecopy('d',   cd,   s,   i);      pad = ws - size(d);            frontporch = round(pad  /  2);      d = padarray(d,   frontporch,   fill,   'pre');      d = padarray(d,   pad - frontporch,   fill,   'post');  % Add  1   pixel white border.      switch  lower(border)          case   'append'              w =  padarray(w,   [1   1],   1,   'post');              h = padarray(h,   [1   0],   1,   'post');              v = padarray(v,   [0  1],   1,   'post');          case   'absorb'              w(:,   end)   =  1;         w(end,   :)   =  1;              h(end,   :)   =  1;          v(:,   end)   =  1;          otherwise              error('Unrecognized BORDER parameter.');          end      w = [w h; v d];                                          % Concatenate coefs.  end  if nargout   == 0      imshow(w);                                               % Display  result.  end  

(2) waveback.m

 function [varargout] = waveback(c, s, varargin)  %WAVEBACK Performs a multi-level two-dimensional inverse FWT.  %   [VARARGOUT] = WAVEBACK(C, S, VARARGIN) computes a 2D N-level  %   partial or complete wavelet reconstruction of decomposition  %   structure [C, S].   %  %   SYNTAX:  %   Y = WAVEBACK(C, S, 'WNAME');  Output inverse FWT matrix Y   %   Y = WAVEBACK(C, S, LR, HR);   using lowpass and highpass   %                                 reconstruction filters (LR and   %                                 HR) or filters obtained by   %                                 calling WAVEFILTER with 'WNAME'.  %  %   [NC, NS] = WAVEBACK(C, S, 'WNAME', N);  Output new wavelet   %   [NC, NS] = WAVEBACK(C, S, LR, HR, N);   decomposition structure  %                                           [NC, NS] after N step   %                                           reconstruction.  %  %   See also WAVEFAST and WAVEFILTER.  %   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins  %   Digital Image Processing Using MATLAB, Prentice-Hall, 2004  %   $Revision: 1.5 $  $Date: 2003/10/13 01:29:36 $  % Check the input and output arguments for reasonableness.  error(nargchk(3, 5, nargin));  error(nargchk(1, 2, nargout));  if (ndims(c) ~= 2) | (size(c, 1) ~= 1)    error('C must be a row vector.');     end  if (ndims(s) ~= 2) | ~isreal(s) | ~isnumeric(s) | (size(s,2) ~= 2)    error('S must be a real, numeric two-column array.');     end  elements = prod(s, 2);  if (length(c) < elements(end)) | ...        ~(elements(1) + 3 * sum(elements(2:end - 1)) >= elements(end))    error(['[C S] must be a standard wavelet ' ...           'decomposition structure.']);   end  % Maximum levels in [C, S].  nmax = size(s, 1) - 2;          % Get third input parameter and init check flags.  wname = varargin{1};  filterchk = 0;   nchk = 0;      switch nargin  case 3     if ischar(wname)           [lp, hp] = wavefilter(wname, 'r');   n = nmax;     else         error('Undefined filter.');       end     if nargout ~= 1         error('Wrong number of output arguments.');       end  case 4     if ischar(wname)        [lp, hp] = wavefilter(wname, 'r');           n = varargin{2};    nchk = 1;     else        lp = varargin{1};   hp = varargin{2};           filterchk = 1;   n = nmax;        if nargout ~= 1            error('Wrong number of output arguments.');          end     end  case 5      lp = varargin{1};   hp = varargin{2};   filterchk = 1;      n = varargin{3};    nchk = 1;  otherwise      error('Improper number of input arguments.');       end  fl = length(lp);  if filterchk                                        % Check filters.    if (ndims(lp) ~= 2) | ~isreal(lp) | ~isnumeric(lp) ...          | (ndims(hp) ~= 2) | ~isreal(hp) | ~isnumeric(hp) ...          | (fl ~= length(hp)) | rem(fl, 2) ~= 0        error(['LP and HP must be even and equal length real, ' ...               'numeric filter vectors.']);     end  end  if nchk & (~isnumeric(n) | ~isreal(n))          % Check scale N.      error('N must be a real numeric.');   end  if (n > nmax) | (n < 1)     error('Invalid number (N) of reconstructions requested.');      end  if (n ~= nmax) & (nargout ~= 2)      error('Not enough output arguments.');   end  nc = c;    ns = s;    nnmax = nmax;             % Init decomposition.  for i = 1:n     % Compute a new approximation.     a = symconvup(wavecopy('a', nc, ns), lp, lp, fl, ns(3, :)) + ...         symconvup(wavecopy('h', nc, ns, nnmax), ...                   hp, lp, fl, ns(3, :)) + ...         symconvup(wavecopy('v', nc, ns, nnmax), ...                   lp, hp, fl, ns(3, :)) + ...         symconvup(wavecopy('d', nc, ns, nnmax), ...                   hp, hp, fl, ns(3, :));      % Update decomposition.      nc = nc(4 * prod(ns(1, :)) + 1:end);     nc = [a(:)' nc];      ns = ns(3:end, :);                       ns = [ns(1, :); ns];      nnmax = size(ns, 1) - 2;  end  % For complete reconstructions, reformat output as 2-D.  if nargout == 1      a = nc;   nc = repmat(0, ns(1, :));     nc(:) = a;      end  varargout{1} = nc;  if nargout == 2      varargout{2} = ns;    end  %-------------------------------------------------------------------%  function z = symconvup(x, f1, f2, fln, keep)  % Upsample rows and convolve columns with f1; upsample columns and  % convolve rows with f2; then extract center assuming symmetrical  % extension.  y = zeros([2 1] .* size(x));      y(1:2:end, :) = x;  y = conv2(y, f1');  z = zeros([1 2] .* size(y));      z(:, 1:2:end) = y;  z = conv2(z, f2);  z = z(fln - 1:fln + keep(1) - 2, fln - 1:fln + keep(2) - 2);  

(3) wavecopy.m

function y = wavecopy(type, c, s, n)   %WAVECOPY Fetches coefficients of a wavelet decomposition structure.   %   Y = WAVECOPY(TYPE, C, S, N) returns a coefficient array based on   %   TYPE and N.     %   %   INPUTS:   %     TYPE      Coefficient category   %     -------------------------------------   %     'a'       Approximation coefficients   %     'h'       Horizontal details   %     'v'       Vertical details   %     'd'       Diagonal details   %   %     [C, S] is a wavelet data structure.   %     N specifies a decomposition level (ignored if TYPE = 'a').   %   %   See also WAVEWORK, WAVECUT, and WAVEPASTE.   %   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins   %   Digital Image Processing Using MATLAB, Prentice-Hall, 2004   %   $Revision: 1.4 $  $Date: 2003/10/13 01:20:41 $   error(nargchk(3, 4, nargin));   if nargin == 4         y = wavework('copy', type, c, s, n);   else        y = wavework('copy', type, c, s);     end  

(4) wavecut.m

function [nc, y] = wavecut(type, c, s, n)  %WAVECUT Zeroes coefficients in a wavelet decomposition structure.  %   [NC, Y] = WAVECUT(TYPE, C, S, N) returns a new decomposition  %   vector whose detail or approximation coefficients (based on TYPE  %   and N) have been zeroed. The coefficients that were zeroed are  %   returned in Y.  %  %   INPUTS:  %     TYPE      Coefficient category  %     -------------------------------------  %     'a'       Approximation coefficients  %     'h'       Horizontal details  %     'v'       Vertical details  %     'd'       Diagonal details  %  %     [C, S] is a wavelet data structure.  %     N specifies a decomposition level (ignored if TYPE = 'a').  %  %   See also WAVEWORK, WAVECOPY, and WAVEPASTE.  %   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins  %   Digital Image Processing Using MATLAB, Prentice-Hall, 2004  %   $Revision: 1.4 $  $Date: 2003/10/13 01:20:09 $  error(nargchk(3, 4, nargin));  if nargin == 4        [nc, y] = wavework('cut', type, c, s, n);  else       [nc, y] = wavework('cut', type, c, s);    end  

(5) wavefast.m

function [c, s] = wavefast(x, n, varargin)   %WAVEFAST Perform multi-level 2-dimensional fast wavelet transform.   %   [C, L] = WAVEFAST(X, N, LP, HP) performs a 2D N-level FWT of   %   image (or matrix) X with respect to decomposition filters LP and   %   HP.   %   %   [C, L] = WAVEFAST(X, N, WNAME) performs the same operation but   %   fetches filters LP and HP for wavelet WNAME using WAVEFILTER.   %   %   Scale parameter N must be less than or equal to log2 of the   %   maximum image dimension.  Filters LP and HP must be even. To   %   reduce border distortion, X is symmetrically extended. That is,   %   if X = [c1 c2 c3 ... cn] (in 1D), then its symmetric extension   %   would be [... c3 c2 c1 c1 c2 c3 ... cn cn cn-1 cn-2 ...].   %   %   OUTPUTS:   %     Matrix C is a coefficient decomposition vector:   %   %      C = [ a(n) h(n) v(n) d(n) h(n-1) ... v(1) d(1) ]   %   %     where a, h, v, and d are columnwise vectors containing   %     approximation, horizontal, vertical, and diagonal coefficient   %     matrices, respectively.  C has 3n + 1 sections where n is the   %     number of wavelet decompositions.    %   %     Matrix S is an (n+2) x 2 bookkeeping matrix:   %   %      S = [ sa(n, :); sd(n, :); sd(n-1, :); ... ; sd(1, :); sx ]   %   %     where sa and sd are approximation and detail size entries.   %   %   See also WAVEBACK and WAVEFILTER.   %   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins   %   Digital Image Processing Using MATLAB, Prentice-Hall, 2004   %   $Revision: 1.5 $  $Date: 2003/10/13 01:14:17 $   % Check the input arguments for reasonableness.   error(nargchk(3, 4, nargin));   if nargin == 3      if ischar(varargin{1})            [lp, hp] = wavefilter(varargin{1}, 'd');      else          error('Missing wavelet name.');         end   else         lp = varargin{1};     hp = varargin{2};      end   fl = length(lp);      sx = size(x);   if (ndims(x) ~= 2) | (min(sx) < 2) | ~isreal(x) | ~isnumeric(x)      error('X must be a real, numeric matrix.');        end   if (ndims(lp) ~= 2) | ~isreal(lp) | ~isnumeric(lp) ...          | (ndims(hp) ~= 2) | ~isreal(hp) | ~isnumeric(hp) ...          | (fl ~= length(hp)) | rem(fl, 2) ~= 0      error(['LP and HP must be even and equal length real, ' ...             'numeric filter vectors.']);    end   if ~isreal(n) | ~isnumeric(n) | (n < 1) | (n > log2(max(sx)))      error(['N must be a real scalar between 1 and ' ...             'log2(max(size((X))).']);       end   % Init the starting output data structures and initial approximation.   c = [];       s = sx;     app = double(x);   % For each decomposition ...   for i = 1:n      % Extend the approximation symmetrically.      [app, keep] = symextend(app, fl);      % Convolve rows with HP and downsample. Then convolve columns      % with HP and LP to get the diagonal and vertical coefficients.      rows = symconv(app, hp, 'row', fl, keep);      coefs = symconv(rows, hp, 'col', fl, keep);      c = [coefs(:)' c];    s = [size(coefs); s];      coefs = symconv(rows, lp, 'col', fl, keep);      c = [coefs(:)' c];      % Convolve rows with LP and downsample. Then convolve columns      % with HP and LP to get the horizontal and next approximation      % coeffcients.      rows = symconv(app, lp, 'row', fl, keep);      coefs = symconv(rows, hp, 'col', fl, keep);      c = [coefs(:)' c];      app = symconv(rows, lp, 'col', fl, keep);   end   % Append final approximation structures.   c = [app(:)' c];       s = [size(app); s];   %-------------------------------------------------------------------%   function [y, keep] = symextend(x, fl)   % Compute the number of coefficients to keep after convolution   % and downsampling. Then extend x in both dimensions.   keep = floor((fl + size(x) - 1) / 2);   y = padarray(x, [(fl - 1) (fl - 1)], 'symmetric', 'both');   %-------------------------------------------------------------------%   function y = symconv(x, h, type, fl, keep)   % Convolve the rows or columns of x with h, downsample,   % and extract the center section since symmetrically extended.   if strcmp(type, 'row')      y = conv2(x, h);      y = y(:, 1:2:end);      y = y(:, fl / 2 + 1:fl / 2 + keep(2));   else      y = conv2(x, h');      y = y(1:2:end, :);      y = y(fl / 2 + 1:fl / 2 + keep(1), :);   end   

(6) wavefilter.m

 function [varargout]=wavefilter(wname,type)   error(nargchk(1,2,nargin));   if(nargin==1 & nargout ~=4) | (nargin==2 & nargout~=2)       error('Invalid number of output arguments.');   end   if nargin==1 & ~ischar(wname)       error('WNAME must be a string.');   end   if nargin==2 & ~ischar(type)       error('TYPE must be a string.');   end    switch lower(wname)       case {'haar','db1'}           ld=[1 1]/sqrt(2); hd=[-1 1]/sqrt(2);           lr=ld;            hr=-hd;       case 'db4'           ld=[-1.059740178499728e-002 3.288301166698295e-002 3.084138183598697e-002 -1.870348117188811e-001 ...               -2.798376941698385e-002 6.308807679295904e-001 7.148465705525415e-001 2.303778133088552e-001];           t=[0:7];           hd=ld; hd(end:-1:1)=cos(pi*t).*ld;           lr=ld; lr(end:-1:1)=ld;           hr=cos(pi*t).*ld;       case 'sym4'           ld=[-7.576571478927333e-002 -2.963552764599851e-002 4.976186676320155e-001 8.037387518059161e-001 ...               2.978577956052774e-001  -9.921954357684722e-002 -1.260396726203783e-002 3.222310060404270e-002];           t=[0:7];           hd=ld; hd(end:-1:1)=cos(pi*t).*ld;           lr=ld; lr(end:-1:1)=ld;           hr=cos(pi*t).*ld;       case 'bior6.8'           ld=[0 1.908831736481291e-003 -1.9142861290088767e-003 -1.699063986760234e-002 1.1934565279772926e-002 ...               4.973290349094079e-002 -7.726317316720414e-002 -9.405920349573646e-002 4.207962846098268e-001 ...               8.259229974584023e-001 4.207962846098268e-001 -9.405920349573646e-002 -7.726317316720414e-002 ...               4.973290349094079e-002 1.193456527972926e-002 -1.699063986760234e-002 -1.914286129088767e-003 ...               1.908831736481291e-003];           hd=[0 0 0 1.442628250562444e-002 -1.446750489679015e-002 -7.872200106262882e-002 4.036797903033992e-002 ...               4.178491091502746e-001 -7.589077294536542e-001 4.178491091502746e-001 4.036797903033992e-002 ...               -7.872200106262882e-002 -1.446750489679015e-002 1.442628250562444e-002 0 0 0 0];           t=[0:17];           lr=cos(pi*(t+1)).*hd;           hr=cos(pi*t).*ld;       case 'jpeg9.7'           ld=[0 0.02674875741080976 -0.01686411844287495 -0.07822326652898785 0.2668641184428723 ...               0.6029490182363579 0.2668641184428723 -0.07822326652898785 -0.01686411844287495  ...               0.02674875741080976];           hd=[0 -0.09127176311424948 0.05754352622849957 0.5912717631142470 -1.115087052456994 ...               0.5912717631142470 0.05754352622849957 -0.09127176311424948 0 0];           t=[0:9];           lr=cos(pi*(t+1)).*hd;           hr=cos(pi*t).*ld;       otherwise            error('Unrecongizable wavelet name (WNAME).');   end   if(nargin==1)       varargout(1:4)={ld,hd,lr,hr};   else        switch lower(type(1))           case 'd'               varargout={ld,hd};           case 'r'               varargout={lr,hr};           otherwise                error('Unrecongizable filter TYPE.');       end   end   

(7) wavepaste.m

 function nc = wavepaste(type, c, s, n, x)  %WAVEPASTE Puts coefficients in a wavelet decomposition structure.  %   NC = WAVEPASTE(TYPE, C, S, N, X) returns the new decomposition  %   structure after pasting X into it based on TYPE and N.  %  %   INPUTS:  %     TYPE      Coefficient category  %     -------------------------------------  %     'a'       Approximation coefficients  %     'h'       Horizontal details  %     'v'       Vertical details  %     'd'       Diagonal details  %  %     [C, S] is a wavelet data structure.  %     N specifies a decomposition level (Ignored if TYPE = 'a').  %     X is a two-dimensional approximation or detail coefficient  %       matrix whose dimensions are appropriate for decomposition  %       level N.  %  %   See also WAVEWORK, WAVECUT, and WAVECOPY.  %   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins  %   Digital Image Processing Using MATLAB, Prentice-Hall, 2004  %   $Revision: 1.4 $  $Date: 2003/10/13 01:21:13 $  error(nargchk(5, 5, nargin))  nc = wavework('paste', type, c, s, n, x);  

(8) wavework.m

 function [varargout] = wavework(opcode, type, c, s, n, x)  %WAVEWORK is used to edit wavelet decomposition structures.  %   [VARARGOUT] = WAVEWORK(OPCODE, TYPE, C, S, N, X) gets the  %   coefficients specified by TYPE and N for access or modification  %   based on OPCODE.  %  %   INPUTS:  %     OPCODE      Operation to perform  %     --------------------------------------------------------------  %     'copy'      [varargout] = Y = requested (via TYPE and N)  %                 coefficient matrix   %     'cut'       [varargout] = [NC, Y] = New decomposition vector  %                 (with requested coefficient matrix zeroed) AND   %                 requested coefficient matrix   %     'paste'     [varargout] = [NC] = new decomposition vector with  %                 coefficient matrix replaced by X  %  %     TYPE        Coefficient category  %     --------------------------------------------  %     'a'         Approximation coefficients  %     'h'         Horizontal details  %     'v'         Vertical details  %     'd'         Diagonal details  %  %     [C, S] is a wavelet toolbox decomposition structure.  %     N is a decomposition level (Ignored if TYPE = 'a').  %     X is a two-dimensional coefficient matrix for pasting.  %  %   See also WAVECUT, WAVECOPY, and WAVEPASTE.  %   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins  %   Digital Image Processing Using MATLAB, Prentice-Hall, 2004  %   $Revision: 1.6 $  $Date: 2003/11/21 15:00:18 $  error(nargchk(4, 6, nargin));  if (ndims(c) ~= 2) | (size(c, 1) ~= 1)     error('C must be a row vector.');     end  if (ndims(s) ~= 2) | ~isreal(s) | ~isnumeric(s) | (size(s, 2) ~= 2)     error('S must be a real, numeric two-column array.');     end  elements = prod(s, 2);                % Coefficient matrix elements.  if (length(c) < elements(end)) | ...        ~(elements(1) + 3 * sum(elements(2:end - 1)) >= elements(end))      error(['[C S] must form a standard wavelet decomposition ' ...             'structure.']);   end  if strcmp(lower(opcode(1:3)), 'pas') & nargin < 6     error('Not enough input arguments.');     end  if nargin < 5     n = 1;      % Default level is 1.  end               nmax = size(s, 1) - 2;                % Maximum levels in [C, S].  aflag = (lower(type(1)) == 'a');  if ~aflag & (n > nmax)     error('N exceeds the decompositions in [C, S].');      end  switch lower(type(1))                 % Make pointers into C.  case 'a'     nindex = 1;     start = 1;    stop = elements(1);    ntst = nmax;  case  {'h', 'v', 'd'}     switch type     case 'h', offset = 0;     % Offset to details.     case 'v', offset = 1;     case 'd', offset = 2;     end     nindex = size(s, 1) - n;      % Index to detail info.     start = elements(1) + 3 * sum(elements(2:nmax - n + 1)) + ...             offset * elements(nindex) + 1;     stop = start + elements(nindex) - 1;     ntst = n;  otherwise     error('TYPE must begin with "a", "h", "v", or "d".');  end  switch lower(opcode)                   % Do requested action.  case {'copy', 'cut'}     y = repmat(0, s(nindex, :));     y(:) = c(start:stop);    nc = c;     if strcmp(lower(opcode(1:3)), 'cut')        nc(start: stop) = 0; varargout = {nc, y};     else         varargout = {y};         end  case 'paste'     if prod(size(x)) ~= elements(end - ntst)        error('X is not sized for the requested paste.');     else        nc = c;   nc(start:stop) = x(:);   varargout = {nc};       end  otherwise     error('Unrecognized OPCODE.');  end  

(9) wavezero.m

function [nc, g8] = wavezero(c, s, l, wname)  %WAVEZERO Zeroes wavelet transform detail coefficients.   %   [NC, G8] = WAVEZERO(C, S, L, WNAME) zeroes the level L detail  %   coefficients in wavelet decomposition structure [C, S] and  %   computes the resulting inverse transform with respect to WNAME  %   wavelets.  %   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins  %   Digital Image Processing Using MATLAB, Prentice-Hall, 2004  %   $Revision: 1.4 $  $Date: 2003/10/13 01:31:35 $  [nc, foo] = wavecut('h', c, s, l);  [nc, foo] = wavecut('v', nc, s, l);  [nc, foo] = wavecut('d', nc, s, l);  i = waveback(nc, s, wname);  g8 = im2uint8(mat2gray(i));  figure; imshow(g8);  

测试程序：

clearf=imread('cameraman.tif');[c,s]=wavefast(f,1,'sym4');%快速小波变换figure;wave2gray(c,s,-6);[nc,y]=wavecut('a',c,s);%近似系数置0figure;wave2gray(nc,s,-6);edges=abs(waveback(nc,s,'sym4'));%边缘重构figure;imshow(mat2gray(edges));

结果：