On qualifying windows for FIR filter design
R. Webster · IEEE Transactions on Acoustics Speech and Signal Processing · 1983
Although several measures of window performance have been defined, none of these directly characterizes the window's application to FIR filter design. But as the number of filter coefficients tends to infinity the peak ripple in the filter response tends to a value that is dependent only on the window. This value, the "Gibbs number," closely approximates the peak ripple for practical filters.