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 the 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.
%
% Taken from: Rafael C. Gonzalez, Richard E. Woods. and Steven L. Eddins,
% Digital Image Processing Using MATLAB®, Prentice-Hall Inc, 2002.

narginchk(4, 6);

if (~ismatrix(c)) || (size(c, 1) ~= 1)
    error('C must be a row vector.');
end

if (~ismatrix(s)) || ~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 strcmpi(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 exeeds 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 = zeros(s(nindex, :));
        y(:) = c(start:stop);
        nc = c;
        if strcmpi(opcode(1:3), 'cut')
            nc(start:stop) = 0;
            varargout = {nc, y};
        else
            varargout = {y};
        end
    case 'paste'
        if numel(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