Median filter

About: Median filter is a research topic. Over the lifetime, 12479 publications have been published within this topic receiving 178253 citations.

Cluster-based adaptive fuzzy switching median filter for universal impulse noise reduction

Abstract: In this paper, we present a novel method for the removal of impulse noise from digital images. The proposed filter, called the Cluster-based Adaptive Fuzzy Switching Median (CAFSM), is composed of a cascaded easy-to- implement impulse detector and a detail preserving noise filter. Initially, the impulse detector classifies any possible impulsive noise pixels. Subsequently, the filtering phase replaces the detected noise pixels. In addition, the filtering phase employs fuzzy reasoning to deal with uncertainties present in local information. Contrary to many existing filters that only focus on a particular impulse noise model, the CAFSM filter is capable of filtering all kinds of impulse noise - the random-valued and/or fixed-valued impulse noise models. Extensive simulations conducted on 100 monochrome images under a wide range of noise densities show that the CAFSM filter substantially outperforms other state-of-the-art impulse noise filters. Furthermore, the relatively fast processing time suggests the CAFSM filter's applicability in consumer electronic products such as digital cameras.

Improved watermarking technique based on significant difference of lifting wavelet coefficients

Abstract: In this paper, a blind watermarking scheme based on significant difference of lifting wavelet transform coefficients has been proposed. The difference between two maximum coefficients in a block is called as significant difference. Embedding of binary watermark has been done based on the largest coefficient of randomly shuffled blocks of CH3 sub-band. This sub-band is quantized using the predefined threshold value by comparing the significant difference value with the average of significant difference value of all blocks. The watermarked image shows no perceptual degradation as the PSNR value exceeds 42 dB. An adaptive-thresholding-based method is used for watermark extraction. In the proposed technique, the benefit of using lifting wavelet over traditional wavelet is the maximum energy compaction property, which helps in resisting different attacks. The simulation results show higher performance of the proposed technique as compared to the similar existing techniques under different geometric and nongeometric attacks such as amplification, median filtering, sharpening, scaling, rotation, Gaussian noise, salt and paper noise, Gaussian filter and JPEG compression.

Model-based image enhancement of far infrared images

Abstract: We devise enhancement algorithms for far infrared images based upon a model of an idealized far infrared image being piecewise-constant. We then apply two known enhancement algorithms: median filtering and spatial homomorphic filtering, and then extend the model to develop spatio-temporal homomorphic filtering. The algorithms have been applied to several image sequences and work well, showing significant image enhancement.

Method of removing noise from digital moving picture data

Abstract: Provided is a method of removing noise from digital moving picture data reducing the number of frames used in a temporal filtering operation and able to detect motion between frames easily. The method comprises a method of spatial filtering, a method of temporal filtering, and a method of performing the spatial filtering and the temporal filtering sequentially. The spatial filtering method applies a spatial filtering in a YCbCr color space, preserving a contour/edge in the image in the spatial domain, and generating a weight that is adaptive to the noise for discriminating the contour/edge in the temporal filtering operation. The temporal filtering method applies temporal filtering based on motion detection and scene change detection, compensating for global motion, the motion detection considering the brightness difference and color difference of the pixels compared between frames in the temporal filtering operation, and a weight that is adaptive to the noise for detecting the motion in the temporal filtering operation. The spatial filtering method is preferably performed first, and the temporal filtering method is performed with the result of the spatial filtering.