How to reduce execution time of a code in matlab R2013a

Attached is the complete code for "Copy move image forgery detection using PCA". The input and output required are also attached with the post. Problem is this code works only for input1, and for other input images it just shows its input image as the output. Please help to rectify the code.kindly also suggest something to reduce the execution time of the code which is nearly 15 minutes.

[Brendan Hamm]

What do you mean the code only works for one input? This is not a function, so there is no input to this file. Please elaborate.

[harpreet]

Sir Brendan Hamm, I mean to say that As i entered the path for image named 'input1' in the code, it gave correct result. So, i tested it on some more images (as attached input2, input3 etc.), Then it didn't give correct output as required. Instead it resulted in the same output as that of image.

[harpreet]

Although the code is not a function, but it needs an image as its input( in the first line of the code) and gives another image as its output

Answer 1

[Brendan Hamm]

To reduce execution time, run the code in the Profiler.

Profiling for Improving Performance

Looking at your code I would suggest attempting to remove the loops if possible and vectorize your code. Furthermore, I would suggest not using the disp() function inside of a for-loop as this takes valuable resources and is not usually necessary. Lastly pre-allocate space for x1,*y1*,etc. that are assigned in the loop. By not pre-allocating you are making a new copy of the data stored in the vector at every iteration in your loop.

[Stephen23]

Useful information to support this answer:

http://www.mathworks.com/help/matlab/matlab_prog/vectorization.html

http://www.mathworks.com/help/matlab/matlab_prog/techniques-for-improving-performance.html