Error in Matlab Code
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marie lasz
am 14 Dez. 2020
Kommentiert: Image Analyst
am 18 Dez. 2020
I am getting error in this code at line 13 '', 'Index in position 2 exceeds array bounds (must not exceed 512). Looking for the solution.Thanks in advance
clear all;
M=512;
N=512;
K=8;
A=imread('lena2.jpg');
A=rgb2gray(A);
A=imresize(A,[512,512]);
b=imread('Watermarked_Image.jpg');
for p=1:N
for q=1:N
x=(p-1)*K+1;
y=(q-1)*K+1;
BLOCK1=A(x:x+K-1,y:y+K-1);
BLOCK2=b(x:x+K-1,y:y+K-1);
BLOCK1=idct2(BLOCK1);
BLOCK2=idct2(BLOCK2);
if BLOCK1(1,1)~=0
a=(BLOCK2(1,1)/BLOCK1(1,1))-1;
if a<0
W(p,q)=0;
else
W(p,q)=1;
end
end
end
end
subplot(2,2,1);
imshow(W);
title('the extracted watermark image');
imwrite(W,'w1.jpg','jpg');
'
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Akzeptierte Antwort
Image Analyst
am 14 Dez. 2020
Matrices are indexed (row, column), which is (y, x), NOT (x,y) as you have it.
Also check the limits of your for loop to make sure you don't step outside the image.
Attach your 2 images if you still need help so we can run your code.
9 Kommentare
Image Analyst
am 18 Dez. 2020
Not sure without delving into it much more than I have time for. I notice that your're using x and y and a lot of novices confuse x and y with row and column. They do NOT correspond like that.
Matrixes are indexed M(row, column) which is M(y, x), NOT M(x,y) so make sure all that is correct. I saw for W you're using p as the first index which is derived from x, so that's not right in general but would be okay for a perfectly square matrix. And you're using x as the first index for A instead of y.
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Cris LaPierre
am 14 Dez. 2020
Error is in this line of code:
BLOCK1=A(x:x+K-1,y:y+K-1);
"Index in position 2 exceeds array bounds (must not exceed 512)"
Position 2 corresponds to your second index: y:y+K-1
Apparently A is a mx512 array. You define y as y=(q-1)*K+1; At its largest value (q=512, K=8), y is 511*8+1, which is >> 512.
You likely need to rethink your approach.
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