A digital image is often deteriorated by impulse noise that may occur during processes such as transmission. An impulse noise converts the pixel data in the image into black (0) or white (255) values at a random frequency and is also called salt-and-pepper noise. In this paper, we identify the details of pixels that have been damaged by impulse noise by analyzing the frequency of the noisy image using non-harmonic analysis (NHA). From experimental results, we can confirm that this method shows superior performance compared to the recent PSNR denoising method. In addition, we show that the proposed method is particularly superior in eliminating impulse noise in images with high noise rates.

We propose a sound field control system to control the sound over a wide area within a room by reducing the influence of the reproduction space using power envelope inverse filtering (PEIF). Envelopes of the impulse response within the room have approximately the same shape at all observation points. Therefore, the proposed sound field control system can control with a small number of loudspeakers a wider area by reducing reverberation in the room through envelope processing. We present experimental data demonstrating that the proposed PEIF system can provide better control than a system that uses minimum phase inverse filtering (MPIF), which is conventionally used for reducing reverberation. Improvement was observed across the frequency band, especially above 1 kHz. Additionally, our PEIF system is more effective over the high-frequency range.