Gersho's bounds on the asymptotic performance of vector quantizers are vali
d for vector distortions which are powers of the Euclidean norm. Yamada, Ta
zaki, and Gray generalized the results to distortion measures that are incr
easing functions of the norm of their argument. In both cases, the distorti
on is uniquely determined by the vector quantization error, i.e., the Eucli
dean difference between the original vector and the codeword into which it
is quantized, We generalize these asymptotic bounds to input-weighted quadr
atic distortion measures and measures that are approximately output-weighte
d-quadratic when the distortion is small, a class of distortion measures of
ten claimed to be perceptually meaningful, An approximation of the asymptot
ic distortion based on Gersho's conjecture is derived as well. We also cons
ider the problem of source mismatch, where the quantizer is designed using
a probability density different from the true source density. The resulting
asymptotic performance in terms of distortion increase in decibels is show
n to be linear in the relative entropy between the true and estimated proba
bility densities.