periodic noise in an image

[sat99]

Hello,

I am new to labview programming,I am trying to remove periodic noise from a grey scale image

IDEA:periodic noise has very sharp peaks(very less width) in amplitude spectrum

The converted pixel values to amplitude spectrum by FFT transformation.To find the periodic signals of very less width I compared the each amplitude spectrum point with all the neighbourhood points .If the difference value is very high then(greater than the thrshold value) then its considered as periodic noise

I have done everything .But upon changing the threshold value along a long range I am unable to find any difference in the output image.Periodic nise is not removed.I am really confused whats the problem is..!! 

I have attached the data file and also the VI .

Could you please give me suggestions.

[RavensFan]

It looks like you are abusing local variables.  You have 2 sections of code running in parallel.  1.  The section that reads the file and performs an FFT.  2.  The section that consists of two 255 iteration For Loops that is doing some number crunching.  Most of those are using local variables while terminals are sitting off to the side  unused.  The problem is that you have no control over what runs first and whether data is read from a local variable or written to a local variable first.  Since section 1 reads from the file, I'm guessing that is going to take longer than the number crunching section 2.  Your original data is going to wind up putting the data into the controls and your number crunching section which is running on no data is going to be overwritten.

Read Dataflow vs Local Variables then take a look at your VI again.