In packet switched networks such as the Internet, packets may get lost during transmission due to, e.g., network
congestion. This leads to a quality degradation of the original signal. As video communication is a bandwidth
consuming application, the original data are first compressed. This compression step increases the impact of
information loss even more. In wavelet based image and video coding, the low frequency data is the most
important. Loss of low frequency coefficients results in annoying black holes in the received images and video.
This effect can be countered by post processing error concealment: a lost coefficient is estimated from its
In this paper we present a locally adaptive interpolation method for the lost low frequency coefficients. For
each lost low frequency coefficient, we estimate the optimal interpolation direction (horizontal or vertical) using
novel error measures. In this way, we preserve the edges in the reconstructed image much better. Compared to
older techniques of similar complexity, our scheme reconstructs images with the same or better quality. This is
reflected in the visual as well as in the numerical results: there is an increase of up to 4.4 dB compared to bilinear
concealment. The proposed scheme is fast and simple, which makes it suitable for real-time applications.