最后,我们以一幅64*64的Lena局部图像来演示EZW算法的编解码效果。
首先给出相关的编解码主程序。
function y=ezw(Im,imDim,codeDim,DecodeDim)
global row col
[row,col]=size(Im);
% ----- Wavedec -----%
DecIm=mywavedec2(Im,imDim);
% ----- Select threshold -----%
MaxDecIm=max(max(abs(DecIm)));
T=zeros(1,codeDim);
T(1)=2^flor(log2(MaxDecIm));
for i=2:codeDim
T(i)=T(i-1)/2;
end
% ----- EZW coding -----%
[CodeList,LenSubCL,QuantiFlagList,LenSubQFL]=ezwcode(DecIm,T,codeDim);
% ----- EZW decoding -----%
DecodeMat=ezwdecode(DecIm,T(1),DecodeDim,CodeList,LenSubCL,QuantiFlagList,LenSubQFL);
% ----- Waverec -----%
DecIm(1:row/8,1:col/8)
DecodeMat(1:row/8,1:col/8)
RecIm=mywaverec2(DecodeMat,imDim);
function [CodeList,LenSubCL,QuantiFlagList,LenSubQFL]=ezwcode(Mat,threshold,codedim)
global row col
scanlist=morton(Mat);
flaglist(1:row,1:col)='Z';
imptvalue=[];
imptflag=[];
% ----- Intializing EZW coding output variables -----%
CodeList=[];
LenSubCL=[];
QuantiFlagList=[];
LenSubQFL=[];
% ----- Coding loop -----%
for d=1:codedim
[imptvalue,imptflag,scancode,scanflag,flaglist]=mainscan(Mat,scanlist,flaglist,imptvalue,imptflag,threshold(d));
[quantilist,quantiflag,recvalue,quantifierMat]=assistscan(imptvalue,d,threshold(1));
% Produce code dataflow
CodeList=[CodeList,scancode];
LenSubCL=[LenSubCL,length(scancode)];
QuantiFlagList=[QuantiFlagList,quantiflag'];
LenSubQFL=[LenSubQFL,length(quantiflag)];
end
function DecodeMat=ezwdecode(Mat,T1,decodeDim,CodeList,LenSubCL,QuantiFlagList,LenSubQFL)
global row col
recvalue=[];
rIlist=[];
quantiflagOld=[];
scanorder=listorder(row,col,1,1);
flagMat(1:row,1:col)='Z';
for level=1:decodeDim
scancode=CodeList(1:LenSubCL(level));
CodeList=CodeList(LenSubCL(level)+1:end);
quantiflag=QuantiFlagList(1:LenSubQFL(level));
QuantiFlagList=QuantiFlagList(LenSubQFL(level)+1:end);
DecodeMat=Mat;
qrNum=1;
scNum=1;
[antiQuantiMat,rIlist,quantiflagOld]=antiquantifier(T1,level,rIlist,quantiflag,quantiflagOld);
[DecodeMat,recvalue,qrNum]=updateRecvalue(DecodeMat,recvalue,qrNum,quantiflag,antiQuantiMat,rIlist);
[DecodeMat,flagMat,recvalue]=decoding(DecodeMat,flagMat,recvalue,antiQuantiMat,quantiflag,rIlist,scanorder,scancode,scNum,qrNum);
% if level<decodeDim
% button = questdlg('Need the nest decode processing ?','Decode Level','Yes','No','Yes');
% if button(1)=='N'
% break;
% end
% end
end
(1)图像3级分解、5级编码、5级解码下的效果图。
ezw(Im64,3,5,5);
分解矩阵DecIm的部分数据
40.9531 87.2344 94.2188 161.2031 64.3125 40.4063 37.5781 65.6875
110.8281 129.3125 91.5625 164.3750 107.1719 50.5469 34.9688 75.2188
150.7813 134.5156 98.0625 164.9688 121.7344 67.5469 28.0938 77.1250
132.9219 117.7656 91.0938 155.3125 117.0781 53.0781 28.1563 83.3750
119.3281 118.5156 95.1875 137.1719 105.8750 30.3906 33.6094 79.6406
100.8906 102.9375 119.2031 132.8438 71.5000 28.6875 38.5313 75.3281
103.2813 85.3750 102.6250 107.4531 31.3594 28.2656 45.3438 79.7813
98.4844 120.0938 134.8438 73.3281 29.1719 33.6094 50.3906 86.0781
解码矩阵DecodeMat的对应数据
42 86 94 162 66 42 38 66
110 130 90 166 106 50 34 74
150 134 98 166 122 66 30 78
134 118 90 154 118 54 30 82
118 118 94 138 106 30 34 78
102 102 118 134 70 30 38 74
102 86 102 106 30 30 46 78
98 122 134 74 30 34 50 86
运行效果:
(2)图像3级分解、10级编码、8级解码下的效果图。
ezw(Im64,3,10,8);
分解矩阵DecIm的部分数据
40.9531 87.2344 94.2188 161.2031 64.3125 40.4063 37.5781 65.6875
110.8281 129.3125 91.5625 164.3750 107.1719 50.5469 34.9688 75.2188
150.7813 134.5156 98.0625 164.9688 121.7344 67.5469 28.0938 77.1250
132.9219 117.7656 91.0938 155.3125 117.0781 53.0781 28.1563 83.3750
119.3281 118.5156 95.1875 137.1719 105.8750 30.3906 33.6094 79.6406
100.8906 102.9375 119.2031 132.8438 71.5000 28.6875 38.5313 75.3281
103.2813 85.3750 102.6250 107.4531 31.3594 28.2656 45.3438 79.7813
98.4844 120.0938 134.8438 73.3281 29.1719 33.6094 50.3906 86.0781
解码矩阵DecodeMat的对应数据
40.7500 87.2500 94.2500 161.2500 64.2500 40.2500 37.7500 65.7500
110.7500 129.2500 91.7500 164.2500 107.2500 50.7500 34.7500 75.2500
150.7500 134.7500 98.2500 164.7500 121.7500 67.7500 28.2500 77.2500
132.7500 117.7500 91.2500 155.2500 117.2500 53.2500 28.2500 83.2500
119.2500 118.7500 95.2500 137.2500 105.7500 30.2500 33.7500 79.7500
100.7500 102.7500 119.2500 132.7500 71.7500 28.7500 38.7500 75.2500
103.2500 85.2500 102.7500 107.2500 31.2500 28.2500 45.2500 79.7500
98.2500 120.2500 134.7500 73.2500 29.2500 33.7500 50.2500 86.2500
运行效果: