matrix Dimension Must Agree

please some suggest me Where I am going wrong, I want to add periodic noise in my Image

if true
tw=imread('twins.tif');
t=rgb2gray(tw);
%Creating Periodic noise
s=size(t);
[x,y]=meshgrid(1:s(1),1:s(2));
p=(sin(x/3+y/5)+1);
t_pn=(im2double(t)+(p/2)/2);
imshow(t),figure,imshow(t_pn); 
  % code
end

[Walter Roberson]

Which line is the problem appearing on?

[Muhammad Ali Qadar]

Error using +

Matrix dimensions must agree.

Error in saltpepper (line 14)

 t_pn=(im2double(t)+(p/2)/2);

Answer 1

[Wayne King]

Without more information about your image size, which you don't provide, it's hard to say, but try transposing the p matrix as I've done below:

 tw=imread('twins.tif');
 t=rgb2gray(tw);
 %Creating Periodic noise
 s=size(t);
 [x,y]=meshgrid(1:s(1),1:s(2));
 p=(sin(x/3+y/5)+1)';
 t_pn=(im2double(t)+(p/2)/2);

[Walter Roberson]

Ah, or using ndgrid() instead of meshgrid() and not doing the transpose.

[Muhammad Ali Qadar]

Worked !!!! Thanks a lot, can you Please Tell me how could you figure out this trick.

[Wayne King]

Glad it worked, not a trick, I think Walter's comment is instructive here.