Dr. Prasad

Do you want to calculate a statistical result or you want to filter the image? your question is unclear.

Image Averaging:

h=fspecial('average',3);

K = imfilter(h,image);

fspecial is a filter designing function with 'average' as filter type and '3' as filter radius.

imfilter will apply this filter to a 2-dimensional image. for a color image you can apply this separately to three layers or to the Y layer of YCbCr image.

However, I would recommend the median filtering as it preserve the edges of image.

K = medfilt2(image,[3 3]);

refer this pdf u will get an idea