NPCR Error
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For Image Quality Parameters I need to find NPCR for 2 images after encryption whose original image have 1 pixel difference. The code is:
% For Grayscale Jpeg Images
C=Cipher Image
C2c=Cipher Image after 1 Pixel difference in Original Image.
siz=M*M;
NPCR=0;
SSS=0;
for i=1:M
for j=1:M
if (C2(i,j)==C2c(i,j))
SSS=SSS;
else
SSS=SSS+1;
end
end
end
SSS=SSS/siz;
NPCR=SSS*100;
I get NPCR value=0.0015. Is my code not OK or the method for Cipher image. I should get a value around 99.67%
Suggest any solutions or error
4 件のコメント
Parveiz Lone
2020 年 5 月 12 日
%% 3. NCPR score and p_value
npcr_score = sum( double( img_a(:) ~= img_b(:) ) ) / num_of_pix;
npcr_mu = ( largest_allowed_val ) / ( largest_allowed_val+ 1 );
npcr_var = ( ( largest_allowed_val) / ( largest_allowed_val+ 1 )^2 ) / num_of_pix;
npcr_pVal = normcdf(npcr_score, npcr_mu, sqrt( npcr_var ) );
npcr_dist = [ npcr_mu, npcr_var ];
採用された回答
Walter Roberson
2012 年 4 月 25 日
The best encryption schemes would show no correlation between the encrypted versions of two original images that were nearly the same but not identical.
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