Unrecognized function or variable 'delta'.

Question

Mostfa Abd El-Aziz 2023-11-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2048887-unrecognized-function-or-variable-delta

回答： Maven Euler 2024-1-1

%function fn = retrieve(X,irow,icol);
watermark = imread('watermark.jpg');
watermark=imresize(watermark,[32 32]);
watermarked_img = imread('watermarked_img.jpg');
[irow icol dim] = size(watermark);
watermark=rgb2gray(watermark);
watermark=im2bw(watermark,0.5);
w = reshape(watermark,irow*icol,1);   
X=[];
rng(1,'twister');
for i=1:size(w,1)
    for j=1:7
        r_range=[5 507];
        x=randi(r_range,1,1);
        y=randi(r_range,1,1);
        temp=[];
        a=delta(watermarked_img,x,y);
        temp=[double(a)];
        for j=-2:2
            if(j~=0)
                temp=[temp ; double(delta(watermarked_img,x+j,y))];  
            end
        end
        for j=-2:2
            if(j~=0)
                temp=[temp ; double(delta(watermarked_img,x,y-j))];  
            end
        end
        X=[X double(temp)];
    end
end
%%%%%%%%%%%%%%%%%%%%%%
global net
out=net(X);
%count1=0;
for i=1:size(out,2)
    if(out(i)>0)
        out(i)=1;
        %count1=count1+1;
    else
        out(i)=0;
    end
end
j=0;
out2=[];
'bbbbbbbbbbbb'
size(out,2)
for i=[1:7:size(out,2)]
    j=j+1;
    t=[out(i) out(i+1) out(i+2) out(i+3) out(i+4) out(i+5) out(i+6)];
    out2(j)=mode(t);
    
end
irow
icol
size(out2,2);
w = reshape(out2,irow,icol);   
[w map]=gray2ind(w,255);
imwrite(uint8(w), 'retrieve.jpg'); 
I = imread('retrieve.jpg'); 
imshow(I)
accuracy();
% T = imread('watermark.jpg'); 
% imshow(T)
% 

3 个评论
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Mostfa Abd El-Aziz 2023-11-18

Dear madhan ravi thanx for your response

kindly, how to define this function ??

Dyuman Joshi 2023-11-18

We can't tell you that because we do not have any information as to what the code is supposed to do or what you want to do.

In case you are asking how to define a function, refer to this - function

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Answer 1

Maven Euler 2024-1-1

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2048887-unrecognized-function-or-variable-delta#answer_1381006

Hi @Mostfa Abd El-Aziz

I understand that you are getting unrecognized function of variable error. The error you are encountering is due to the use of delta, which is not defined as a function in the MATLAB code you have provided. It appears that delta is meant to be a custom function that you are using to process the image at specific pixel coordinates (x,y). You need to define this function or replace it with the correct MATLAB function that performs the intended operation.

Here is how you can define your own custom functions in MATLAB: https://www.mathworks.com/help/matlab/ref/function.html

Thanks,

Ayush