Bilateral filter

About: Bilateral filter is a research topic. Over the lifetime, 3500 publications have been published within this topic receiving 75582 citations.

Correcting defect pixels in a digital image

Abstract: Systems and methods of correcting one or more defect pixels in a source image are described. The source image is formed from a plurality of pixels each having a respective value. In one scheme, a defect pixel is corrected based upon curvature information computed from pixel values located near the defect pixel. In another scheme, a median pixel value is determined from values of pixels located near a defect pixel, and the defect pixel is corrected based upon the median pixel value.

Enhancing text-like edges in digital images

Abstract: Systems and methods of enhancing text-like edges in digital images are described. In one aspect, pixels in a block (27) of image pixels are segmented into first and second pixel classes (29, 31). The pixel block (27) is edge enhanced in response to a determination that the pixel block (27) likely contains at least one text-like edge based on a measure of distance separating intensity values respectively representing intensity distributions of the first and second classes (29, 31) and based on measures of peakedness of intensity histograms computed for both the first and second pixel classes (29, 31).

Image processing apparatus, imaging apparatus, image processing method and recording medium

Abstract: Sharpness is calculated in all of focus-bracketed images on a pixel basis. Then, a first reference value indicating an image of the plurality of images to which a pixel whose sharpness is the highest among the pixels located on the identical positions in the plurality of images belongs is obtained on each pixel of the images, and a second reference value is calculated based on the first reference value on each pixel by spatially smoothing the first reference value on each pixel based on the first reference values on adjacent pixels. The focus-bracketed images are processed based on the second reference values to generate an omni-focus image or a blur-enhanced image. Accordingly, it is possible to judge a region having high contrast as an in-focus region and acquire a synthesized image having smooth gradation.

On Fast Bilateral Filtering Using Fourier Kernels

Abstract: It was demonstrated in earlier work that, by approximating its range kernel using shiftable functions, the nonlinear bilateral filter can be computed using a series of fast convolutions. Previous approaches based on shiftable approximation have, however, been restricted to Gaussian range kernels. In this work, we propose a novel approximation that can be applied to any range kernel, provided it has a pointwise-convergent Fourier series. More specifically, we propose to approximate the Gaussian range kernel of the bilateral filter using a Fourier basis, where the coefficients of the basis are obtained by solving a series of least-squares problems. The coefficients can be efficiently computed using a recursive form of the QR decomposition. By controlling the cardinality of the Fourier basis, we can obtain a good tradeoff between the run-time and the filtering accuracy. In particular, we are able to guarantee subpixel accuracy for the overall filtering, which is not provided by the most existing methods for fast bilateral filtering. We present simulation results to demonstrate the speed and accuracy of the proposed algorithm.

A new image denoising method based on the bilateral filter

Abstract: In this paper we propose a new method to reduce noise in digital images. The method is based on the bilateral filter. The bilateral filter is a nonlinear filter that does spatial averaging without smoothing edges. The spatial averaging aspect of the bilateral filter is very crucial; the bilateral filter has been shown to work better than wavelet thresholding in some recent papers. The proposed method improves the bilateral filter through decomposing a signal into its frequency components. In this way, noise in different frequency components can be eliminated. Experimental results with both simulated and real images are given. In addition to this new method, we also provide an empirical study of the optimal parameter selection for the bilateral filter.