waveback.asv

jpeg在matlab下的仿真实现

function [varargout] = waveback(c, s, varargin)
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(s)) | ~(elements(1) + 3 * sum(elements(2:end - 1)) >=elements(end))
    error(['[C S] must be a standard wavelet' ...
            'decomposition structure.']);
end
nmax = size(s, 1) - 2;
wname = carargin{1};  filterchk = 0;  nchk = 0;
switch nargin
    case 3
        if ischar(wname)
            [lp, hp] = wavefilter(wname, 'r');  n = nmax;
        else
            error('Undefined filter.');
        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
f1 = length(lp);
if filterchk
    if (ndims(lp) ~= 2) | ~isreal(lp) | ~isnumeric(lp) ...
            | (ndims(hp) ~= 2 | ~isreal(hp) | ~isnumeric(hp) ...
            | (f1 ~= length(hp)) | rem(f1, 2) ~=0)
        error('LP and HP must be even and equal length real,numeric filter vectors.');
    end
end
if (nchk & (~isnumeric(n) | ~isreal))
    error('N must be a real numeric.');
end
if (n > max) | (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;
for i = 1:n
    a = symconvup(wavecopy('a', nc, ns), lp, lp, f1, ns(3, :)) + ...
        symconvup(wavecopy('h', nc, ns, nnmax), hp, lp, f1, ns(3, :)) + ...
        symconvup(wavecopy('v', nc, ns, nnmax), lp, hp, f1, ns(3, :)) + ...
        symconvup(wavecopy('d', nc, ns, nnmax), hp, hp, f1, ns(3, :));
    nc = nc(4 * prod(ns(1, :)) + 1:end);   nc = [a(:)' nc];
    ns = ns(3:end, :);
    nnmax = size(ns, 1) - 2;
end
if nargout == 1
    a = nc;   nc = repmat(0, ns(s, :))