Combined one-dimensional lowpass and highpass filters for subband transformer

Subband transformation coefficients are typically computed by first filtering and downsampling of an input uncompressed signal and then subsequently filtering and downsampling the result intermediate signals with a set of lowpass and highpass filters. State-of-the-art subband transformers are complex, which increases consumed power. A novel method for significantly decreasing the complexity of subband transformers to a minimum is presented. This solution was implemented in a field programmable gate array, together with various methods for compression and decompression.