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how use parfor for image encryption

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omar A.alghafoor
omar A.alghafoor 2020-7-26
评论： omar A.alghafoor 2020-7-31
Hi .....
I am trying to write this code in parallel but I couldn't do that :
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [layer_image] = Encryption_SBOX(layer_image,SBox)
[rows,cols,~] = size(layer_image);
%upperLeft
STARTblockImage1_rows=1;
STARTblockImage1_cols=1;
ENDblockImage1_rows=floor(rows/2);
ENDblockImage1_cols=floor(cols/2);
%upperRight
% STARTblockImage2_rows=1;
STARTblockImage2_cols=floor(cols/2);
% ENDblockImage2_rows=floor(rows/2);
% ENDblockImage2_cols=cols;
%lowerLeft
STARTblockImage3_rows=floor(rows/2);
% STARTblockImage3_cols=1;
% ENDblockImage3_rows=rows;
% ENDblockImage3_cols=floor(cols/2);
% lowerRight5
STARTblockImage4_rows=floor(rows/2);
STARTblockImage4_cols=floor(cols/2);
% ENDblockImage4_rows=rows;
% ENDblockImage4_cols=cols;
BZ=16; % block size
% flipfiop=0;
for i=STARTblockImage1_rows:BZ:ENDblockImage1_rows0
for j=STARTblockImage1_cols:BZ:ENDblockImage1_cols
iblock=i;
while(iblock<=i+BZ)&&(iblock<=ENDblockImage1_rows)
jblock=j;
while(jblock<=j+BZ)&&(jblock<=ENDblockImage1_cols)
%upperLeft
x = dec2bin(layer_image(iblock,jblock),8);
x = dec2bin(Temp1(i,j),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
layer_image(iblock,jblock)=SBox(ld+1,rd+1);
% layer_image(iblock,jblock)=flipfiop;
upperRight
if ((jblock+STARTblockImage2_cols)<=cols)
x = dec2bin(layer_image(iblock,(jblock+STARTblockImage2_cols)),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
layer_image(iblock,(jblock+STARTblockImage2_cols))=SBox(ld+1,rd+1);
else
disp(jblock+STARTblockImage2_cols);
end
%lowerLeft
x = dec2bin(layer_image(iblock+STARTblockImage3_rows,jblock),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
layer_image(iblock+STARTblockImage3_rows,jblock)=SBox(ld+1,rd+1);
%lowerRight
x = dec2bin(layer_image(iblock+STARTblockImage4_rows,jblock+STARTblockImage4_cols),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
layer_image(iblock+STARTblockImage4_rows,jblock+STARTblockImage4_cols)=SBox(ld+1,rd+1);
jblock=jblock+1;
end
iblock=iblock+1;
end
end
end
  3 个评论
显示 1更早的评论
Walter Roberson
Walter Roberson 2020-7-26
Which variable are you trying to parfor over?
omar A.alghafoor
omar A.alghafoor 2020-7-27
编辑：Walter Roberson 2020-7-28
I rewrite above code :
function [layer_image] = Encryption_SBOX(layer_image,SBox)
[rows,cols,~] = size(layer_image);
%upperLeft
STARTblockImage1_rows=1;
STARTblockImage1_cols=1;
ENDblockImage1_rows=floor(rows/2);
ENDblockImage1_cols=floor(cols/2);
%upperRight
STARTblockImage2_rows=1;
STARTblockImage2_cols=floor(cols/2)+1;
ENDblockImage2_rows=floor(rows/2);
ENDblockImage2_cols=cols;
%lowerLeft
STARTblockImage3_rows=floor(rows/2)+1;
STARTblockImage3_cols=1;
ENDblockImage3_rows=rows;
ENDblockImage3_cols=floor(cols/2);
% lowerRight5
STARTblockImage4_rows=floor(rows/2)+1;
STARTblockImage4_cols=floor(cols/2)+1;
ENDblockImage4_rows=rows;
ENDblockImage4_cols=cols;
% block size
% flipfiop=0;
%parparing buffer for rows in 4 blocks
Temp1=layer_image(1,floor(cols/2));
Temp2=layer_image(1,floor(cols/2)+1:cols);
Temp3=layer_image(floor(rows/2)+1,floor(cols/2));
Temp4=layer_image(floor(rows/2)+1,cols);
for i=STARTblockImage1_rows:ENDblockImage1_rows
Temp1=layer_image(i,ENDblockImage1_cols);
Temp2=layer_image(i,STARTblockImage2_cols:ENDblockImage2_cols);
Temp3=layer_image(STARTblockImage3_rows+i,ENDblockImage1_cols);
Temp4=layer_image(STARTblockImage4_rows+i,STARTblockImage1_cols+1:ENDblockImage4_cols);
parfor j=STARTblockImage1_cols:ENDblockImage1_cols
%upperLeft
x = dec2bin(Temp1(i,j),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
Temp1(i,j)=SBox(ld+1,rd+1);
% upperRight
x = dec2bin(Temp2(i,j),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
Temp2(i,j)=SBox(ld+1,rd+1);
% %lowerLeft
x = dec2bin(Temp3(i,j),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
Temp3(i,j)=SBox(ld+1,rd+1);
% % %lowerRight
x = dec2bin(Temp4(i,j),8);
l = x(1, 1 : 4);
r = x(1, 5 : 8);
ld = bin2dec(l); % row
rd = bin2dec(r); % column
Temp4(i,j)=SBox(ld+1,rd+1);
end
layer_image(i,ENDblockImage1_cols)=Temp1;
layer_image(i,STARTblockImage2_cols:ENDblockImage2_cols)=Temp2;
layer_image(STARTblockImage3_rows+i,ENDblockImage1_cols)=Temp3;
layer_image(STARTblockImage4_rows+i,STARTblockImage1_cols+1:ENDblockImage4_cols)=Temp4;
end
end
but there are error :
Error using test_nested_parallel (line 65)
Index in position 2 exceeds array bounds (must not exceed 1).
I think because temp( 1or others)

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回答（1 个）

Walter Roberson
Walter Roberson 2020-7-26
编辑：Walter Roberson 2020-7-26
% layer_image(iblock,jblock)=flipfiop;
upperRight
You do not have any function or variable named upperRight
  3 个评论
显示 1更早的评论
Walter Roberson
Walter Roberson 2020-7-28
If you expect an RGB image then why are you using
Temp1=layer_image(1,floor(cols/2));
which would be for accessing a grayscale or colormap image?
Consider
Temp1=layer_image(1,floor(cols/2),:);
However, if you are only passing in one color pane at a time, then
[rows,cols,~] = size(layer_image);
confuses the issue -- it would not technically be wrong, but it would lead the reader to expect that there is a 3rd dimension.

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