how to obtain rms error

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Mahua Nandy(Pal) 2012-10-11

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评论： Image Analyst 2020-1-18

采纳的回答： Image Analyst

Please tell me how to calculate the rms error in image registration?

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Image Analyst 2012-10-11

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Wouldn't it just go like this

difference = single(image1) - single(image2);
squaredError = difference .^ 2;
meanSquaredError = sum(squaredError(:)) / numel(image1);
rmsError = sqrt(meanSquaredError);

Of course you could compact that all into one line if you want.

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MAT-Magic 2020-1-18

编辑：Image Analyst 2020-1-18

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@Image Analyst, can I use this formula for two vectors having same length?

difference = single(image1) - single(image2);
squaredError = difference .^ 2;
meanSquaredError = sum(squaredError(:)) / numel(image1);
rmsError = sqrt(meanSquaredError); 

Image Analyst 2020-1-18

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Yes, you can, but I'd use mean() instead of sum to simplify it:

differenceImage = single(image1) - single(image2);
squaredErrorImage = differenceImage .^ 2;
meanSquaredError = mean(squaredErrorImage(:)) % A scalar
rmsError = sqrt(meanSquaredError)

And if they're vectors of the same shape (row or column) then you don't even need the (:).

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Daniel Shub 2012-10-11

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编辑：Daniel Shub 2012-10-11

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Just to be a little bit difference. If you have the DSP system toolbox you can do

step(dsp.RMS('Dimension', 'all'), x)

where x is your error signal. So in the case of two imagines (image1 and image2)

image1 = randn(128);
image2 = randn(128);
x = image1-image2;

I calculated the RMS value of my image registration algorithm by using your code. But I can't understand how to do a validation for my registration algorithm with th RMS value. Can you tell me please how can I com to conclusions about the accuracy of my registration algorithm with the use of RMS values?

Ishara Nipuni 2019-1-25

I calculated the RMS value with getting the same image as image1 and image2. But the value was not zero. But I think that it should be zero. Can you please explain me about it?

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