ERROR From STD 'standard deviation'

Hello every one; is anyone knows how can I extract the error between two images from their variance? knowing that I have the STD which equals = SQRT(Variance)

Thanks ;

Answer 1

[Image Analyst]

If you define error as the standard deviation of the absolute value of the difference between the image intensities, then you can do

differenceImage = abs(double(image1) - double(image2));
theErros = std(differenceImage(:));

You might also look at other definitions, like MSE ( http://en.wikipedia.org/wiki/Mean_squared_error), PSNR ( http://en.wikipedia.org/wiki/PSNR), and SSIM ( http://en.wikipedia.org/wiki/SSIM).

[Soum]

Thank you :)

No,I ask how can I get The Error from the standard deviation i have already the value of the std but what i want is the Error anyway my Question like that: the error in function of the std

ERROR=F(STD) ????

Hope You can answer me

[Shashank Prasanna]

Error is a concept. All these are just proxies or a way to quantify error.

[Soum]

In my case the ERROR=(Noisy Image-De-noised Image), but I know the SDT and I wanna get the ERROR ok??

[Image Analyst]

You cannot get a difference image, (Noisy Image-De-noised Image), from a single number, like 6.54868543 for example. I hope you understand why. It seems so basic that I shouldn't even have to explain why. What if I told you the mean of an image? Could you tell me what the original image looked like? No, of course not, because there are an infinite number of images that could have that mean. Well it's the same with the standard deviation - there's just not enough information to recover the original image(s).

[Soum]

mmm ok Thanks