How can I identify an image inside of a larger image?

I have two pictures. One is a small image of Waldo and the other is a much larger image with him hiding somewhere. My goal is to create a program that will find Waldo using only the functions length, size, imread, and image. This is what I have so far.

 [row,column,layer] = size(Waldo);
 [row_,column_,layer_] = size(wheresWaldo);
 counter = 0;
for i = 1:1:row_
    for j = 1:1:column_
        for k = 1:1:layer_
            if wheresWaldo(i,j,1) == Waldo(1,1,1) && wheresWaldo(i,j,2) == Waldo(1,1,2) && wheresWaldo(i,j,3) == Waldo(1,1,3)

                counter = counter + 1;
                ivals(counter) = i;
                jvals(counter) = j;
            end
        end
    end
end

What I am doing here is taking the first pixel of the Waldo image and seeing where the R G B values of that pixel occur in the wheresWaldo image. I found several instances and stores them in the variables ivals and jvals. ivals represent rows and jvals represents columns.

Answer 1

[Image Analyst]

You can use normalized cross correlation with normxcorr2(), or you can use isequal() (if the small image and large image match exactly pixel for pixel). See attached demo.

[Andrew Padilla]

Hi. Please take a look at my post again. I cannot use either of those functions. I listed the functions that I am allowed to use. I need to take advantage of for loops and if statements.

[Image Analyst]

You will need the outer loops to scan your little image over the larger image. Then, at each location, you'll need another pair of loops to compare every pixel (all 3 colors) of the small image to the large image. So you're missing a pair of for loops.