when i apply crop attack on watermarked image it give me this error( Error in ==> extraction at 18 green = X(:,:,2);) while i embedd a watermark in blue channel how can i solve this problem? how can i apply crop attack?

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shameen khan
shameen khan 2015-5-28
评论： shameen khan 2015-5-29
when i apply crop attack on watermarked image it give me this error( Error in ==> extraction at 18 green = X(:,:,2);) while i embedd a watermark in blue channel how can i solve this problem? how can i apply crop attack

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回答（2 个）

Walter Roberson
Walter Roberson 2015-5-28
Your watermarkrgb.png was created with a single layer, not as RGB.
You should get into the habit of writing in code to check for valid input before attempting operations.
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shameen khan
shameen khan 2015-5-28
NO. after embedding a watermark in blue channel i used cat function for cancatenation of three layer then write image as watermarkrgb
Walter Roberson
Walter Roberson 2015-5-28
How much does it cost you to put in a test to see whether the image you read in actually has 3 layers? Do they still charge 20 cents per punched card like they used to in my day?

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Image Analyst
Image Analyst 2015-5-28
Your code has lots of stuff commented out. Like Walter said, your X is not 3D, full color RGB. Your code is essentially this:
X=imread('watermarkrgb.png');
green = X(:,:,2);
And it needs to be this:
originalImage = imread('watermarkrgb.png');
[rows, columns, numberOfColorChannels] = size(originalImage);
if numberOfColorChannels == 1
% It's monochrome, not full RGB
% Create the needed color channels.
red = originalImage;
green = originalImage;
blue= originalImage;
else
% It's full color. Just extract the color channels
% from the RGB image.
red = originalImage(:,:,1);
green = originalImage(:,:,2);
blue = originalImage(:,:,3);
end
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Image Analyst
Image Analyst 2015-5-29
SW1=SU1*sW11*SV1'; is not in my code. This looks like a totally new error that can be solved with this link. You need to check the dimensions of all 3 of those arrays.

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