Narrow Results

This work describes a new adaptive rank-order filter, which can be useful for image enhancement or as an early processing stage for segmentation purposes. The filter output is selected among the rank-ordered grey values of the observation window, and the output’s rank depends adaptively on a local measure of the spatial order, to be defined suitably. The aim of this adaptation is to allow the filter to meet conflicting requirements, namely noise and texture smoothing, edge sharpening and enhancement of the fine-structured detail. The definition of a measure of the spatial order is discussed, and experimental results, obtained with natural images of different types, are displayed.

In this paper, we present a novel noise suppression and detail preservation algorithm. The test image is firstly pre-processed through a multiresolution analysis employing the discrete wavelet transform. Then, we apply a fast and robust total variation technique, incorporating a statistical representation in the style of maximum likelihood estimation. Finally, we compare this proposed approach to current state-of-the-art denoising methods using synthetic and real images. The results demonstrate encouraging performance of our algorithm.

Multifocus image fusion can obtain an image with all objects in focus, which is beneficial for understanding the target scene. Multiscale transform (MST) and sparse representation (SR) have been widely used in multifocus image fusion. However, the contrast of the fused image is lost after multiscale reconstruction, and fine details tend to be smoothed for SR-based fusion. In this paper, we propose a fusion method based on MST and convolutional sparse representation (CSR) to address the inherent defects of both the MST- and SR-based fusion methods. MST is first performed on each source image to obtain the low-frequency components and detailed directional components. Then, CSR is applied in the low-pass fusion, while the high-pass bands are fused using the popular “max-absolute” rule as the activity level measurement. The fused image is finally obtained by performing inverse MST on the fused coefficients. The experimental results on multifocus images show that the proposed algorithm exhibits state-of-the-art performance in terms of definition.