The convolution operation is a mathematical operation which
takes two functions f(x) and g(x) and produces a third function
h(x). Mathematically, convolution is defined as:
g(x) is referred to as the filter. The integral only needs to
be evaluated over the range where 
is nonzero (called the
support of the filter).[18]
In spatial domain image processing, you discretize the
operation. f(x) becomes an array of pixels F[x]. The kernel
g(x) is an array of values G[0...(width-1)] (assume finite
support). Equation 7 becomes:
