www.gusucode.com > wavelet工具箱matlab源码程序 > wavelet/compression/wcompress.m
function varargout = wcompress(option,varargin)
%WCOMPRESS True compression of images using wavelets.
%
% The WCOMPRESS command performs either compression or uncompression of
% grayscale or truecolor images.
%
% Compression:
% ===========
% WCOMPRESS('c',X,SAV_FILENAME,COMP_METHOD) compresses the image X using
% the compression method COMP_METHOD. The compressed image is saved in
% the file SAV_FILENAME. If you do not have write permission in the
% current working directory, WCOMPRESS changes directory to tempdir and
% writes the .wtc file in that directory.
%
% X can be either a 2-D array containing an indexed image or a 3-D array
% of uint8 containing a truecolor image.
%
% Both the row and column size of the image must be powers of two.
%
% WCOMPRESS('c',FILENAME,...) loads the image X from the file FILENAME
% which is a MATLAB Supported Format(MSF) file: MAT-file or other
% image files (see IMREAD).
%
% WCOMPRESS('c',I,...) converts the indexed image X = I{1}
% to a truecolor image Y using the colormap map = I{2} and then
% compresses Y.
%
% The valid compression methods are divided in three categories.
% 1) Progressive Coefficients Significance Methods (PCSM):
% - 'ezw': Embedded Zerotree Wavelet.
% - 'spiht': Set Partitioning in Hierarchical Trees.
% - 'stw': Spatial-orientation Tree Wavelet.
% - 'wdr': Wavelet Difference Reduction.
% - 'aswdr': Adaptively Scanned Wavelet Difference Reduction
% - 'spiht_3d': Set Partitioning in Hierarchical Trees 3D
% for truecolor images.
% For more details on these methods, see the references and
% specially Walker and also Said and Pearlman.
%
% 2) Coefficients Thresholding Methods (CTM-1):
% - 'lvl_mmc': Subband thresholding of coefficients and
% Huffman encoding.
% For more details on this method, see the Strang and Nguyen
% reference.
%
% 3) Coefficients Thresholding Methods (CTM-2):
% - 'gbl_mmc_f': Global thresholding of coefficients and
% fixed encoding.
% - 'gbl_mmc_h': Global thresholding of coefficients and
% Huffman encoding.
%
% -------------------------------------------------------------------
% NOTE: The Discrete Wavelet Transform uses the periodized extension
% mode.
% -------------------------------------------------------------------
%
% All the compression methods use parameters which have default values.
% These values may be changed using the following syntax:
% WCOMPRESS(... ,'ParName1',ParVal1,'ParName2',ParVal2, ...)
% Some of the parameters are related to display or to data transform
% functionalities. The others are linked to the compression process
% itself.
%
% Data transform parameters.
% - 'ParName' = 'wname' or 'WNAME' sets the wavelet name.
% ParVal is a string (see waveletfamilies). The default is bior4.4.
%
% - 'ParName' = 'level' or 'LEVEL' sets the level of decomposition.
% ParVal is an integer such that: 1 <= level <= levmax which is
% the maximum possible level (see wmaxlev).
% The default level depends on the method:
% . for PCSM methods level is equal levmax.
% . for CTM methods level is equal to fix(levmax/2).
%
% If you specify a level greater than levmax, wcompress uses levmax.
%
% - 'ParName' = 'it' or 'IT' sets Image type Transform.
% ParVal must be one of the following strings:
% 'n' : no conversion (default), image type (truecolor or
% grayscale) is automaticaly detected.
% 'g' : grayscale transformation type.
% 'c' : color transformation type (RGB uint8).
%
% - 'ParName' = 'cc' or 'CC' sets Color Conversion parameter
% if X is a truecolor image.
% ParVal must be one of the following strings:
% 'rgb' or 'none' : No conversion (default).
% 'yuv' : YUV color space transform.
% 'klt' : Karhunen-Loeve transform.
% 'yiq' : YIQ color space transform.
% 'xyz' : CIEXYZ color space transform.
%
% Parameter for Progressive Coefficients Significance Methods (PCSM)
% - 'ParName' = 'maxloop' or 'MAXLOOP' sets the maximum number of
% steps for the compression algorithm.
% ParVal must be a positive integer or Inf (default is 10).
%
% Parameters for Coefficients Thresholding Methods (CTM-1)
% One among the two following parameters may be used:
% - 'ParName' = 'bpp' or 'BPP' sets the bit-per-pixel ratio.
% ParVal must be such that:
% 0 <= ParVal <= 8 (grayscale) or 24 (truecolor)
%
% - 'ParName' = 'comprat' or 'COMPRAT' sets the compression ratio.
% ParVal must be such that: 0 <= ParVal <= 100.
%
% Parameters for Coefficients Thresholding Methods (CTM-2)
% Two parameters may be used. The first one is related to
% the threshold and the second one is the number of classes for
% quantization.
%
% 1) The first one may be chosen among the five following
% parameters:
% - 'ParName' = 'threshold' or 'THRESHOLD' sets the threshold value
% for compression.
% ParVal must be a positive (or zero) real number.
%
% - 'ParName' = 'nbcfs' or 'NBCFS' sets the number of preserved
% coefficients in the wavelet decomposition.
% ParVal must be an integer such that: 0 <= ParVal <= total
% number of coefficients of wavelet decomposition.
%
% - 'ParName' = 'percfs' or 'PERCFS' sets the percentage of
% preserved coefficients in the wavelet decomposition.
% ParVal must be a real number such that: 0 <= ParVal <= 100.
%
% - 'ParName' = 'bpp' or 'BPP' sets the bit-per-pixel ratio.
% ParVal must be such that:
% 0 <= ParVal <= 8 (grayscale) or 24 (truecolor)
%
% - 'ParName' = 'comprat' or 'COMPRAT' sets the compression ratio.
% ParVal must be such that: 0 <= ParVal <= 100.
%
% 2) The second parameter sets the number of classes for
% quantization:
% - 'ParName' = 'nbclas' or 'NBCLAS' sets the number of classes.
% ParVal must be a real number such that: 2 <= ParVal <= 200.
%
% Display parameter.
% - 'ParName' = 'plotpar' or 'PLOTPAR' sets the plot parameter.
% ParVal must be one of the following strings or numbers:
% 'plot' or 0: plots only the compressed image.
% 'step' or 1: displays each step of the encoding process
% (only for PCSM methods).
%
% [COMPRAT,BPP] = WCOMPRESS('c',...) allows also to return the
% compression ratio COMPRAT and the bit_per_pixel ratio BPP.
%
% Uncompression:
% =============
% XC = WCOMPRESS('u',SAV_FILENAME) uncompresses the file
% SAV_FILENAME and returns the image XC. Depending on the
% initial compressed image, XC can be a 2-D array containing
% an indexed image or a 3-D array of uint8 containing a
% truecolor image.
%
% The directory containing SAV_FILENAME must be on the MATLAB path. If
% WCOMPRESS does not find the .wtc file on the path, WCOMPRESS changes
% directory to tempdir and attempts to read the .wtc file from tempdir.
%
% XC = WCOMPRESS('u',SAV_FILENAME,'plot') plots the
% uncompressed image.
%
% XC = WCOMPRESS('u',SAV_FILENAME,'step') shows the
% step by step uncompression only for PCSM methods.
%
% The behavior of wcompress has changed. This includes:
% - The default behavior for writing and reading .wtc files. Prior to
% R2016b, the majority of data written to .wtc files used unit32
% precision. In R2016b, this was changed to uint64.
%
% If this change in behavior has adversely affected your code, you may
% preserve the previous behavior while compressing with:
%
% WCOMPRESS('c',X,SAV_FILENAME,COMP_METHOD,'legacy')
%
%
% Example 1:
% %--------------------------------------------------------------
% % This example shows first how to compress a
% % jpeg image using the 'stw' compression method and
% % save it to a file.
% % Then, it shows how to load the stored image from
% % the file and display the step by step uncompression.
% %--------------------------------------------------------------
% wcompress('c','arms.jpg','comp_arms.wtc','stw');
% wcompress('u','comp_arms.wtc','step');
%
% Example 2:
% %--------------------------------------------------------------
% % This example shows first how to compress a
% % jpeg image using the 'aswdr' compression method and
% % save it to a file.
% % During the compression process 3 parameters are used:
% % - Conversion color (cc) set to Karhunen-Loeve transform 'klt'
% % - Maximum number of loops for computing (maxloop) set to 11
% % - Plot type (plotpar) set to step by step display
% % Then, it shows how to load the stored image from
% % the file and display the step by step uncompression.
% %--------------------------------------------------------------
% [cr,bpp] = wcompress('c','woodstatue.jpg','woodstatue.wtc', ...
% 'aswdr','cc','klt','maxloop',11,'plotpar','step')
% wcompress('u','woodstatue.wtc','step');
% delete('woodstatue.wtc')
%
% Example 3:
% %--------------------------------------------------------------
% % Compression and uncompression of a grayscale image
% % and computed MSE and PSNR error values.
% %
% % Two measures are commonly used to quantify the error between
% % two images: the Mean Square Error(MSE) and the Peak Signal
% % to Noise Ratio (PSNR) which is expressed in decibels.
% %
% % This example shows first how to compress the mask image
% % using the 'spiht' compression method and save it to the file
% % 'mask.wtc'.
% % Then, it shows how to load the stored image from the file
% % 'mask.wtc', uncompress it and delete the file 'mask.wtc'.
% %--------------------------------------------------------------
% load mask;
% [cr,bpp] = wcompress('c',X,'mask.wtc','spiht','maxloop',12)
% Xc = wcompress('u','mask.wtc');
% delete('mask.wtc')
% D = abs(X-Xc).^2;
% mse = sum(D(:))/numel(X)
% psnr = 10*log10(255*255/mse)
% % Display the original and the compressed image
% colormap(pink(255))
% subplot(1,2,1); image(X); title('Original image'); axis square
% subplot(1,2,2); image(Xc); title('Compressed image'); axis square
%
% Example 4:
% %--------------------------------------------------------------
% % Compression and uncompression of a truecolor image
% % and computed MSE and PSNR error values.
% % Compression parameters are the same as those used for example 3,
% % but using the 'spiht_3d' method give better performance yet.
% %--------------------------------------------------------------
% X = imread('wpeppers.jpg');
% [cr,bpp] = wcompress('c',X,'wpeppers.wtc','spiht','maxloop',12)
% Xc = wcompress('u','wpeppers.wtc');
% delete('wpeppers.wtc')
% D = abs(double(X)-double(Xc)).^2;
% mse = sum(D(:))/numel(X)
% psnr = 10*log10(255*255/mse)
% % Display the original and the compressed image
% subplot(1,2,1); image(X); title('Original image'); axis square
% subplot(1,2,2); image(Xc); title('Compressed image'); axis square
%
% See also IMREAD, IMWRITE, WMAXLEV, TEMPDIR, MATLABPATH
% M. Misiti, Y. Misiti, G. Oppenheim, J.M. Poggi 11-Feb-2008.
% Last Revision: 12-Apr-2012.
% Copyright 1995-2012 The MathWorks, Inc.
%Check for 'legacy' flag, remove from varargin. Set typeSAVE
[typeSAVE,varargin] = getlegacyoption('legacy',varargin);
nbIN = length(varargin);
option = lower(option(1));
switch lower(option)
case 'c' % COMPRESS
if ischar(varargin{1})
try
[X,map,imgFormat] = wloadimages(varargin{1}); %#ok<NASGU>
catch ME
throw(ME);
end
elseif iscell(varargin{1})
X = varargin{1}{1};
map = varargin{1}{2};
else
X = varargin{1};
end
Sav_filename = varargin{2};
method_COMP = varargin{3};
% Default Wavelet Transform Settings (WTS).
%------------------------------------------
validateattributes(X,{'numeric'},{'real','nonempty','finite'},...
'wcompress','X');
if isrow(X) || iscolumn(X)
error(message('Wavelet:FunctionArgVal:InvalidXYSizes'));
end
sX = size(X);
SS = log2(sX(1:2));
if any(SS~=fix(SS))
error(message('Wavelet:divGUIRF:WTC_Pow2_Size'));
end
if (size(X,3) ~= 1 && size(X,3) ~= 3)
error(message('Wavelet:FunctionArgVal:InvalidThirdDim'));
end
level_MAX = wmaxlev(sX,'haar');
wname_DEF = 'bior4.4';
extMode_DEF = 'per';
% Other Defaults.
%----------------
ColCONV_DEF = 'rgb'; % Default Color Transform.
stepFLAG_DEF = NaN; % Default for plot param (none).
nbclas_DEF = 75;
switch method_COMP
case {'gbl_mmc_h','gbl_mmc_f'}
methodPARAMS_DEF = struct('percfs',0.05,'nbclas',nbclas_DEF);
level_DEF = round(level_MAX/2);
case 'lvl_mmc'
methodPARAMS_DEF = 0.25; % Default Fixed_BitRate
level_DEF = round(level_MAX/2);
otherwise
methodPARAMS_DEF = [];
level_DEF = level_MAX;
end
MaxLoop_DEF = level_DEF+2;
% Initialization of parameters.
%------------------------------
wname = [];
level = [];
extMode = [];
bpp = [];
comprat = [];
percfs = [];
nbcfs = [];
nbclas = [];
threshold = [];
MaxLoop = [];
methodPARAMS = [];
ColCONV = [];
stepFLAG = [];
imgTypeTRANS = [];
% Check arguments.
%-----------------
for k=4:2:nbIN
argNAM = varargin{k};
argVAL = varargin{k+1};
switch lower(argNAM)
case 'it' , imgTypeTRANS = argVAL;
case 'wname' , wname = argVAL;
case 'level' , level = argVAL;
case 'wt'
if iscell(argVAL)
switch length(argVAL)
case 1 , wname = argVAL{1};
case 2 , [wname,level] = deal(argVAL{:});
case 3 , [wname,level,extMode] = deal(argVAL{:});
end
elseif isstruct(argVAL)
fn = lower(fieldnames(argVAL));
for j = 1:length(fn)
currFN = fn{j}(1:3);
switch currFN
case 'wna' , wname = argVAL.(fn{j});
case 'lev' , level = argVAL.(fn{j});
case 'ext' , extMode = argVAL.(fn{j});
end
end
end
case 'cc' , ColCONV = varargin{k+1};
case 'bpp' , bpp = varargin{k+1};
case 'comprat' , comprat = varargin{k+1};
case 'percfs' , percfs = varargin{k+1};
case 'nbclas' , nbclas = varargin{k+1};
case 'thr' , threshold = varargin{k+1};
case 'maxloop' , MaxLoop = varargin{k+1};
case 'params' , methodPARAMS = varargin{k+1};
case 'plotpar'
if isequal(argVAL,'plot') || isequal(argVAL,0)
stepFLAG = 0;
elseif isequal(argVAL,'step') || isequal(argVAL,1)
stepFLAG = 1;
elseif isequal(argVAL,2)
stepFLAG = 2;
else
stepFLAG = NaN;
end
end
end
if isempty(wname) , wname = wname_DEF; end
if isempty(level) , level = level_DEF; end
if isempty(extMode) , extMode = extMode_DEF; end
if isempty(ColCONV), ColCONV = ColCONV_DEF; end
if isempty(stepFLAG) , stepFLAG = stepFLAG_DEF; end
if level>level_DEF
level = level_DEF;
end
% Image type transform and properties.
%-------------------------------------
if ~isempty(imgTypeTRANS)
switch imgTypeTRANS(1)
case 'g' , X = wconvimg('col2idx',X);
case 'c' , X = wconvimg('idx2col',X,map);
end
sX = size(X);
else
if exist('map','var') && ~isempty(map) && ...
~isequal(map(:,1),map(:,2))
X = wconvimg('idx2col',X,map);
sX = size(X);
end
end
nb_Cfs = prod(sX);
if length(sX)==2 , nbPlan = 1; else nbPlan = 3; end
% Compress image with the selected method.
%------------------------------------------
switch method_COMP
case {'gbl_mmc_h','gbl_mmc_f'}
if isempty(nbclas) , nbclas = nbclas_DEF; end
if isempty(methodPARAMS)
if ~isempty(threshold)
methodPARAMS = {threshold,nbclas};
else
okParams = false;
if ~isempty(bpp)
typeARG ='bpp'; valARG = bpp;
elseif ~isempty(comprat)
typeARG ='comprat'; valARG = comprat;
elseif ~isempty(nbcfs)
typeARG ='nbcfs'; valARG = nbcfs;
elseif ~isempty(percfs)
typeARG ='percfs'; valARG = percfs;
else
okParams = true;
methodPARAMS = methodPARAMS_DEF;
end
if ~okParams
[~,nb_Kept_Cfs] = getcompresspar(method_COMP, ...
nb_Cfs,nbPlan,typeARG,valARG);
methodPARAMS = ...
struct('nbcfs',nb_Kept_Cfs,'nbclas',nbclas);
end
end
else
if isstruct(methodPARAMS) && ...
~isfield(methodPARAMS,'nbclas')
methodPARAMS.nbclas = nbclas;
end
end
Encoded_wtbx_DEC = wtcmngr('enc',typeSAVE,method_COMP,...
X,{level,wname,extMode},methodPARAMS,ColCONV);
case 'lvl_mmc'
if isempty(methodPARAMS)
if ~isempty(bpp)
methodPARAMS = bpp;
elseif ~isempty(comprat)
bpp = (comprat*8*size(X,3))/100;
methodPARAMS = bpp;
else
methodPARAMS = methodPARAMS_DEF;
end
end
Encoded_wtbx_DEC = wtcmngr('enc',typeSAVE,method_COMP,...
X,{level,wname,extMode},methodPARAMS,ColCONV);
case {'ezw','spiht','spiht_3d','wdr','aswdr','stw'}
if isempty(MaxLoop)
if ~isempty(bpp)
[~,MaxLoop,~,comprat] = getcompresspar(...
method_COMP,nb_Cfs,nbPlan,'bpp',bpp); %#ok<NASGU>
elseif ~isempty(comprat)
[~,MaxLoop,~,comprat] = getcompresspar(...
method_COMP,nb_Cfs,nbPlan,'comprat',comprat); %#ok<NASGU>
else
MaxLoop = MaxLoop_DEF;
end
end
Encoded_wtbx_DEC = wtcmngr('enc',typeSAVE,method_COMP,X, ...
wname,level,extMode,MaxLoop,ColCONV,stepFLAG);
end
fileSize = wtcmngr('save',typeSAVE,Sav_filename,method_COMP,Encoded_wtbx_DEC);
% Compute Compression Ratio.
%--------------------------
varargout{1} = 100*fileSize/numel(X); % Compression Ratio
varargout{2} = (fileSize*8*size(X,3))/numel(X); % Bits Per Pixel
case 'u' % UNCOMPRESS
inputFile = varargin{1};
stepFLAG = NaN;
if nbIN>1
plotPARAM = varargin{2};
if isequal(plotPARAM,'plot') || isequal(plotPARAM,0)
stepFLAG = 0;
elseif isequal(plotPARAM,'step') || isequal(plotPARAM,1)
stepFLAG = 1;
elseif isequal(plotPARAM,2)
stepFLAG = 2;
else
stepFLAG = NaN;
end
end
X_decoded = wtcmngr('read',typeSAVE,inputFile,stepFLAG);
varargout{1} = X_decoded;
end
function [typeSAVE,arglist] = getlegacyoption(legacyflag,arglist)
found = false;
typeSAVE = 3;
iarg = 1;
while iarg <= numel(arglist)
arg = arglist{iarg};
if ischar(arg) && isrow(arg)
matches = find(strncmpi(arg,legacyflag,length(arg))); %#ok<EFIND>
if ~isempty(matches)
if ~found
found = true;
typeSAVE = 2;
arglist(iarg) = [];
end
else
iarg = iarg + 1;
end
else
iarg = iarg + 1;
end
end