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?

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

Answer 1

[Walter Roberson]

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.

[shameen khan]

NO. after embedding a watermark in blue channel i used cat function for cancatenation of three layer then write image as watermarkrgb

[Walter Roberson]

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?

Answer 2

[Image Analyst]

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

[shameen khan]

when i change my code according to your code it give me this error

Error using ==> mtimes

Inner matrix dimensions must agree.

Error in ==> extraction1 at 68 SW1=SU1*sW11*SV1';

[Image Analyst]

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.

[shameen khan]

ok .thanks for you great help