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finding sum of nxn matirx data

Posted on 2003-11-03
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Last Modified: 2010-04-17
Hi,

    i have an array of pixel data. x,y value of each pixel is known.
   I have to find the sum of nxn pixels around the given pixel(including the pixel)

  that is for the pixel at (x,y). 3x3 sum will be
(x-1,y+1)+(x,y+1)+(x+1,y+1)+(x+1,y)+(x,y)+(x+1,y-1)+(x,y-1)+(x-1,y-1)+(x-1,y).

This calculation should be dynamic, that is for any nxn , the sum should be computed.
i would like to know the way to go abt doing this.


regards,
ric
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Question by:rickynair
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4 Comments
 
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Accepted Solution

by:
JNSTAUB earned 140 total points
ID: 9669808
you have to create a function:

function filter_pixel(x,y,n)
if x>1 AND y>1 and x<n-1 and y<n-1 then
filter_pixel=(x-1,y+1)+(x,y+1)+(x+1,y+1)+(x+1,y)+(x,y)+(x+1,y-1)+(x,y-1)+(x-1,y-1)+(x-1,y)
else
all the border' case
else

end if
end function
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Expert Comment

by:mlmcc
ID: 9671786
Why are you trying to do this?  Is this homework perhaps?

mlmcc
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LVL 2

Expert Comment

by:wellilein
ID: 9672411
Try it with a nested loop

funct filterpixel(x,y,n)
int sum=0
for int i=x-n to x+n
     for int k=y-n to y+n
          sum += getPixelValueAtPosition(i,k)
return sum
end funct

and implement a function named getPixelValueAtPosition() that checks if pixel coordinates are inside your image and returns the pixel value for it.

Above code is not valid for any programming language, so if it is homework, it's not a complete solution. Is that ok this way, mlmcc?
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LVL 101

Expert Comment

by:mlmcc
ID: 9673004
You will need to subtract the value at (x,y)

mlmcc
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