How the number of times n of the patchwork increase?

clc;
A=imread('C:\Users\hp\Desktop\matlab\pictures\lenna.png');%sample image
rnd_x = randperm(size(A,1)-128,7);%choose 7 random unique points on x-axis
rnd_y = randperm(size(A,2)-128,7);%choose 7 random unique points on y-axis
image(A)
for ii = 1:4
    for jj = 5:7
        piece{jj} = A((rnd_x(jj):(rnd_x(jj)+127)),(rnd_y(jj):(rnd_y(jj)+127)),1:3)+1;
        A((rnd_x(jj):(rnd_x(jj)+127)),(rnd_y(jj):(rnd_y(jj)+127)),1:3)= piece{jj}; % add the changed pixel values to the original image A
        a=imadjust(jj);        
       
    end
    piece{ii} = A((rnd_x(ii):(rnd_x(ii)+127)),(rnd_y(ii):(rnd_y(ii)+127)),1:3)-1;%Convert chosen numbers to image pieces
    A((rnd_x(ii):(rnd_x(ii)+127)),(rnd_y(ii):(rnd_y(ii)+127)),1:3)= piece{ii}; % add the changed pixel values to the original image A
    b=imadjust(ii);    
   
end
imshow(A)

The above is my coding running good but it give me the following error."Error using randperm K must be less than or equal to N.

Error in file (line 3)

rnd_x = randperm(size(A,1)-128,6000);%choose 7 random unique points on x-axis"

when I want to choose 6000 or 4000 random unique points on x-axis or y-axis in the place of 7 like the following code:

clc;
A=imread('C:\Users\hp\Desktop\matlab\pictures\lenna.png');%sample image
rnd_x = randperm(size(A,1)-128,6000);%choose 7 random unique points on x-axis
rnd_y = randperm(size(A,2)-128,6000);%choose 7 random unique points on y-axis
image(A)
for ii = 1:3000
    for jj = 3001:6000
        piece{jj} = A((rnd_x(jj):(rnd_x(jj)+127)),(rnd_y(jj):(rnd_y(jj)+127)),1:3000)+1;
        A((rnd_x(jj):(rnd_x(jj)+127)),(rnd_y(jj):(rnd_y(jj)+127)),1:3000)= piece{jj}; % add the changed pixel values to the original image A
        a=imadjust(jj);        
       
    end
    piece{ii} = A((rnd_x(ii):(rnd_x(ii)+127)),(rnd_y(ii):(rnd_y(ii)+127)),1:3000)-1;%Convert chosen numbers to image pieces
    A((rnd_x(ii):(rnd_x(ii)+127)),(rnd_y(ii):(rnd_y(ii)+127)),1:3000)= piece{ii}; % add the changed pixel values to the original image A
    b=imadjust(ii);    
   
end
imshow(A)

I actually need help in the number of times n of the patchwork increase from 7 up to 6000.

Answer 1

[Rik]

You don't check if your image is actually large enough to allow 6000 unique indices. You should either reduce the number of samples in such a case, or increase the resolution of your image.

[John schwan]

@rik Thank you so much for the speedy and your kind responce! I increase my image resolution from 512*512 to 1536*1536 but it dosn't work...

I am matlab beginner for that i do not understand the error generated by the matlab but I think there is the problem with randperm function that I used...

I need help in increasing number of patches up to 6000 and decrease the size of the each patch.

[Rik]

How can you select 6000 unique elements from a list of 1536 elements? That is the core issue.

[John schwan]

@Rik Thank you so much I get it now...

This error is solved but now it give me another error "index exceeds matrix dimensions"...

[Rik]

You expect me to fix a bug in your new code, without showing me any changes? I can do a lot with Matlab, but mind reading is not one of them.

[John schwan]

clc;
A=imread('C:\Users\hp\Desktop\matlab\matlab\pictures\leena.png ');%sample image
rnd_x = randperm(size(A,1)-2,6001);%choose 6000 random unique points on x-axis
rnd_y = randperm(size(A,2)-2,6001);%choose 6000 random unique points on y-axis
image(A)
for ii = 1:3000
    for jj = 3001:6001
        piece{jj} = A((rnd_x(jj):(rnd_x(jj)+1)),(rnd_y(jj):(rnd_y(jj)+1)),1:3000)+1;
        A((rnd_x(jj):(rnd_x(jj)+1)),(rnd_y(jj):(rnd_y(jj)+1)),1:3000)= piece{jj}; % add the changed pixel values to the original image A
        a=imadjust(jj);        
       
    end
    piece{ii} = A((rnd_x(ii):(rnd_x(ii)+1)),(rnd_y(ii):(rnd_y(ii)+1)),1:3000)-1;%Convert chosen numbers to image pieces
    A((rnd_x(ii):(rnd_x(ii)+1)),(rnd_y(ii):(rnd_y(ii)+1)),1:3000)= piece{ii}; % add the changed pixel values to the original image A
    b=imadjust(ii);    
   
end
imshow(A)

This is the code in which I made changes. It gives me the following error:

Index exceeds matrix dimensions.

Error in ImageIntoPatches (line 8)

piece{jj} = A((rnd_x(jj):(rnd_x(jj)+1)),(rnd_y(jj):(rnd_y(jj)+1)),1:3000)+1;

[Rik]

You're doing several indexing operations there. Have you checked the array sizes at that point?

piece{jj} = A( ...
    (rnd_x(jj):(rnd_x(jj)+1)),...
    (rnd_y(jj):(rnd_y(jj)+1)),...
    1:3000) ...
    +1;

• Is rnd_x guaranteed to have at least jj elements?
• Is the first dimension of A large enough to have at least rnd_x(jj)+1 elements?
• Does the second dimension of A have rnd_y(jj)+1 elements?
• Does the third dimension of A have 3000 elements?

[John schwan]

Thank you very much. I will search them all. I hope to find a solution.