loop for image encryption gives error
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sadiqa ilyas
am 31 Jul. 2019
Kommentiert: sadiqa ilyas
am 1 Aug. 2019
I am using 8*8 matrix for image encryption but there is an error in loop which i cannot figure out why.
Km=[K11 K12;K21 K22];% 8 cross 8 matrix
I=imread('lena256.jpg');
imshow(I);
[X Y]=size(I);
for i=1:X
for j=1:4:Y
P=double(I(i,j:j+3));
EncImg(i,j:j+3)=mod((Km*P')',256);
end
error is in EncImg(i,j:j+3)=mod((Km*P')',256))
7 Kommentare
Walter Roberson
am 31 Jul. 2019
Most jpg images are rgb even when they look gray. Real grayscale jpg images are rare. You should always check ndims of a jpg image and rgb2gray if it is not 2.
Akzeptierte Antwort
KALYAN ACHARJYA
am 31 Jul. 2019
for j=1:4:Y-3
12 Kommentare
KALYAN ACHARJYA
am 1 Aug. 2019
Bearbeitet: KALYAN ACHARJYA
am 1 Aug. 2019
You are continously changing the code.
Initialy
P=double(EncImg(i,j:j+7,z));
Now
P=double(I2(i,j:j+7));
Now another term I2, Have you defined I2? Be ensure that all variables or images must be defined before it used.
It would be better, if you provide the complete code, what you have, all inputs required (images also), the code you have tried so far and what result you are expecting.
Walter Roberson
am 1 Aug. 2019
When you use
[X Y]=size(I);
then that acts like
temp = size(I);
X = temp(1);
Y = prod(temp(2:end));
For RGB files, that results in Y being 3 times the number of columns instead of being the number of columns.
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sadiqa ilyas
am 1 Aug. 2019
4 Kommentare
Walter Roberson
am 1 Aug. 2019
This is getting close to the point where I have to stop you and say that we cannot help you any further. Due to the laws of the USA, we can effectively only discuss encryption here as long as your program is pretty broken, to the point where someone else would have trouble using the code to implement a working encryption function. When we start getting to the point where there is a chance that your program might start working, we cannot assist you further and we cannot permit you to post code that is nearly working.
The laws of the USA about this might not be wise or convenient, but we have to live with them.
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