Kernel adaptive filter

About: Kernel adaptive filter is a research topic. Over the lifetime, 8771 publications have been published within this topic receiving 142711 citations.

Detail-preserving adaptive conditional median filters

Abstract: We propose a conditional median filter that is able to preserve significantly more image detail than the conventional median filter when suppression of impulsive noise is desired. It does so by means of bypassing filtering when the local signal variation is below an adaptively adjusted threshold. Another advantage of our algorithm is that it is simple to implement and it can be used with any of the available fast median filter algorithms. In addition, it can be easily integrated into existing median filter hardware. We compare the complexity of our algorithm with that of another proposed algorithm with similar filtering objectives. The performance of the new algorithm on real images is compared to that of median and center-weighted median filters.

An In/Post-Loop Deblocking Filter With Hybrid Filtering Schedule

Abstract: In this paper, we propose a high-throughput deblocking filter to perform the in-loop or post-loop filtering process for different standard requirements. The performance improvement is very mild if we replace a post-loop filter with an in-loop filter. To alleviate this problem, we derive an integration-oriented algorithm that can be reconfigured as the in-loop or post-loop filter. Moreover, we develop a hybrid filtering schedule to reach a lower bound of processing cycles. In particular, we reschedule the filtering order and reuse the intermediate pixels when the deblocking filter switches the filtered edges from vertical to horizontal direction. Finally, a 0.18-mum CMOS design that performs the in/post-loop filter with the hybrid filtering schedule is implemented. The synthesized gate counts are 21.1 K which is reduced to 70% of preliminary design that performs the in-loop or post-loop filter separately. Moreover, it achieves 4times105 macroblock/s of throughput rate at a 100-MHz clock rate.

Multistage adaptive filters for in-phase processing of line-frequency signals

Abstract: The authors describe two adaptive multistage digital filters for 50/60-Hz line-frequency signal processing in zero-crossing detectors and synchronous power systems. These filters combine a median filter with adaptive predictors, either finite-impulse response (FIR)- or infinite-impulse response (IIR)-based, thus making it possible to extract the sinusoidal signals from noise and strong disturbances without phase shifting the primary frequency signal. The median filter is used as a prefilter because it can remove deep commutation notches from the waveform. Adaptation allows the filters to track the exact instantaneous line frequency and avoids the selectivity problem encountered with a fixed filter.

On the optimality of nonunitary filter banks in subband coders

Abstract: This paper investigates the energy compaction capabilities of nonunitary filter banks in subband coding. It is shown that nonunitary filter banks have larger coding gain than unitary filter banks because of the possibility of doing half-whitening in each channel. For long filter unit pulse responses, optimization of subband coding gain for stationary input signals results in a filter bank decomposition, where each channel works as an optimal open-loop DPCM system. We derive a formula giving the optimal filter response for each channel as a function of the input psd. For shorter filter bank responses, good gain is obtained by suboptimal half-whitening responses, but the impact on the theoretical coding gain is still highly significant. Image coding examples demonstrate that better performance is achieved using nonunitary filter banks when the input images are in correspondence with the signal model.

Adaptive Sine-Modulated/Cosine-Modulated Filter Bank Equalizer for Transmultiplexers

Abstract: Cosine-modulated filter banks provide an efficient realization for filter bank-based trans- multiplexers. This paper describes an equalization method for these systems. At the receiver we have two parallel analysis filter banks (cosine- and sine- modulated FBs) whose subchannel outputs are com- bined optimally. This increases the computational burden on the filter bank side, but very simple sub- channel equalizer structure is a clear advantage. For adaptive implementation, the number of required general multipliers is reduced, and it is possible to develop LMS-based equalization algorithms with fast convergence. Therefore, the equalizer structure is called as Adaptive SMFB/CMFB Equalizer for Transmultiplexers (ASCET).