calculation of mean , standard deviation and average for each pixel in an image M*N?
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if i have an image M*N
if i want to making each pixel in the center of window with 31*31 size , and then compute the average and standard deviation and the mean based on pixel 's nighborhoods ? how this can be done?
i dont mean computing the mean , standard deviation , and average for the whole image?
i wait any help
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Answers (2)
Teja Muppirala
on 23 Jan 2012
If you have the Image Processing Toolbox, the functions
IMFILTER (can be used to do mean filtering on a neighborhood),
STDFILT (standard deviation on a neighborhood),
or the more general NLFILTER (arbitrary function on a neighborhood),
are there to do these types of operations quite easily.
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David Young
on 22 Jan 2012
To get the means, you can do
means = conv2(Image, ones(31)/(31*31), 'valid');
Note that means(1,1) is the mean for the window centred on Image(16,16), and so on.
I'm not sure how the average is different from the mean.
To get the SDs, just extend the technique above in the obvious way, using the standard formula for the SD.
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David Young
on 22 Jan 2012
It's true that I haven't told you how to compute the neighbourhood SDs, but once you understand how the neighbourhood means are computed I am sure you'll be able to see how to get the SDs - you just need to apply the same technique to the pointwise square of the image and look up the formula for the SD.
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