# Correlation and Convolution [duplicate]

Both Correlation and Convolution are displacement function, i.e they are used to slide the filter mask across the image.

Convolution is same as correlation except that the filter mask is rotated 180 degree before computing the sum of products.

We mostly use convolution. why it is widely used? why convolution is preferred over correlation?

We have,

 Convolution in time domain   = Multiplication in Frequency domain


Do we have any similar relation for correlation ?

Correlation in time domain  =  _______________ in Frequency domain ?


Please note that for complex-valued signals, complex conjugates are needed for correlation, but neither signal is conjugated in the convolution. So it is only partially true for real valued signals that Convolution is same as correlation except that the filter mask is rotated 180 degree before computing the sum of products.