sir im doing a simple program to identify pixel value and compare with another image,

when i run this code i am getting this error.

"Index exceeds matrix dimensions.
Error in myfu1n (line 10)
subblock = I(r:r+7, c:c+7);"

my complete code

clc;
clear all;
close all;
I = rgb2gray(imread('tablet.jpg'));
original = rgb2gray(imread('tablet1.jpg'));
original = double(original);
for( j = 0 : 1:7)
    r = randi(225-7);
    c = randi(225-7);
    subblock = I(r:r+7, c:c+7);
    imshow(subblock);
    figure;
    t = [1 1];
    [s fval] = fminunc(@myfun , subblock)
end
y=myfun(I)

separate function

%%myfun(I)
function f = myfun(x)
scale = 0.7;
J = imresize(x, scale); 
theta = 30;
x0 = imrotate(J,theta);
for( i = 1:1:225)
 f = (x^2 - x0(i)^2);
end

Answer 1

[Geoff Hayes]

vani - are you sure that your image is 225x225? Rather than hardcoding the dimensions, use size to determine the number of rows and columns

 numRows = size(I,1);
 numCols = size(I,2);
 for( j = 0 : 1:7)
    r = randi(numRows - 7)
    c = randi(numCols - 7);
    subblock = I(r:r+7, c:c+7, 1);
    % etc.
 end

The 1 in subblock may not be necessary as presumably I is two dimensional (due to the conversion from RGB to grayscale).

Answer 2

[vani shree]

thank you sir.. its working properly im getting values. but still it is showing error in function part. Error using ^ MPOWER is not fully supported for integer classes. Both inputs must be scalar. To compute elementwise POWER, use POWER (.^) instead.

Error in myfun (line 7) f = (x^2 - x0(i) ^2);

Error in myfu1n (line 14) f = myfun(I)

 can you please help me again sir

code %%myfun(I) function f = myfun(x) scale = 0.7; J = imresize(x, scale); theta = 30; x0 = imrotate(J,theta); for( i = 1:1:225) f = (x^2 - x0(i)^2); end