  Wavelet coefficients are estimated recursively at progressively coarser
scales recursively. As a result, the estimation is prone to multiplicative
propagation of truncation errors due to quantization and round-off at each
stage. Yet, the influence of this propagation on wavelet filter output has not
been explored systematically. Through numerical error analysis of a simple,
generic sub-band coding scheme with a half-band low pass finite
impulse-response filter for down sampling, we show that truncation error in
estimated wavelet filter coefficients can quickly reach unacceptable levels,
and may render the results unreliable especially at coarser scales.
