Noise reduction

About: Noise reduction is a research topic. Over the lifetime, 25121 publications have been published within this topic receiving 300815 citations. The topic is also known as: denoising & noise removal.

Spatial adaptive wavelet thresholding for image denoising

Abstract: Wavelet thresholding with uniform threshold has shown some success in denoising. For images, we propose that this can be improved by adjusting thresholds spatially, based on the rationale that detailed regions such as edges and textures tolerate some noise but not blurring, whereas smooth regions tolerate blurring but not noise. The proposed algorithm is based on multiscale edge detection and image segmentation and then thresholding the coefficients of different regions with adaptive thresholds.

A 13 bit ISDN-band oversampled ADC using two-stage third order noise shaping

Abstract: A 13-bit 80-kHz baseband analog-to-digital converter suitable for use in applications such as the ISDN U-interface is described. Two-stage third-order noise shaping permits the use of asampling frequency of only 2.56 MHz. The circuit has been implemented using conventional single-ended switched-capacitor techniques in a 1.5- mu m CMOS process. >

Random resampling masks: a non-Bayesian one-shot strategy for noise reduction in digital holography

Abstract: Holographic imaging may become severely degraded by a mixture of speckle and incoherent additive noise. Bayesian approaches reduce the incoherent noise, but prior information is needed on the noise statistics. With no prior knowledge, one-shot reduction of noise is a highly desirable goal, as the recording process is simplified and made faster. Indeed, neither multiple acquisitions nor a complex setup are needed. So far, this result has been achieved at the cost of a deterministic resolution loss. Here we propose a fast non-Bayesian denoising method that avoids this trade-off by means of a numerical synthesis of a moving diffuser. In this way, only one single hologram is required as multiple uncorrelated reconstructions are provided by random complementary resampling masks. Experiments show a significant incoherent noise reduction, close to the theoretical improvement bound, resulting in image-contrast improvement. At the same time, we preserve the resolution of the unprocessed image.

3-TFT active pixel sensor with correlated double sampling readout circuit for real-time medical x-ray imaging

Abstract: This paper presents a current-programmed, current-output active pixel sensor (APS) suitable for real time x-ray imaging (e.g., fluoroscopy) using hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) technology and an appropriate CMOS readout circuit. The proposed pixel circuit can successfully compensate for characteristic variations such as mobility and threshold voltage shift in a-Si:H TFTs. The proposed readout circuit exploits correlated double sampling (CDS) technique not only for reducing the offset current and low frequency noise, but also to reduce the effect of fixed-pattern noise (FPN) on the array operation. The on-pixel amplification reduces the input referred noise to levels that can satisfy the strict requirements for low noise digital fluoroscopy.