IM3CONVOLUTION(r;f;i;cr;cg;cb;d) applies the convolution filter in the 3×3 matrix f to the RGB image in matrix r; scalar i (default 1) defines the intensity parameter; scalars cr, cg and cb contain 0 or 1 (default) according to whether the red, green and blue channels, respectively, are to be modified. If the “feedback” defined by scalar d is 0 (default), the new value at each point is i multiplied by the sum of the values at the point and nearby points multiplied by the convolution matrix.
Alternatively, if d=i (default), the new value at each point is calculated by taking (1-i) multiplied by the current value at the point, and then subtracting i multiplied by the sum of the values at the point and nearby points multiplied by the values in the convolution matrix.