Correlation and Convolution 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 ?
Convolution as associative, while correlation is not.  The associative property is what allows you to convolve multiple filters into a single one, and then convolve that one filter with the image.  That is the big advantage of convolution over correlation.