This work addresses the problem of signal dependent noise removal in images. An adaptive nonlinear filtering approach in the orthogonal transform domain is proposed and analyzed for several typical noise environments in the DCT domain. Being applied locally, i.e., within a window of small support, DCT is expected to approximate the Karhunen-Loeve decorrelating transform, which enables effective...

Collaborative filtering (CF) methods are widely adopted by existing recommender systems, which can analyze and predict user ‘‘ratings’’ or ‘‘preferences’’ of newly generated items based on user historical behaviors. However, privacy issue arises in this process as sensitive user private data are collected by the recommender server. Recently proposed privacy-preserving collaborative filtering (P...

A homomorphic feedforward network (HFFN) for nonlinear adaptive filtering is introduced. This is achieved by a two-layer feedforward architecture with an exponential hidden layer and logarithmic preprocessing step. This way, the overall input-output relationship can be seen as a generalized Volterra model, or as a bank of homomorphic filters. Gradient-based learning for this architecture is int...

Wireless sensor networks are used to sample the environment in a distributed way. Therefore, it is mandatory for all of the measurements to be tightly synchronized in order to guarantee that every sensor is sampling the environment at the exact same instant of time. The synchronization drift gets bigger in environments suffering from temperature variations. Thus, this work is focused on improvi...

An approach to multi-channel blind deconvolution is developed, which uses an adaptive filter that performs blind source separation in the Fourier space. The approach keeps (during the learning process) the same permutation and provides appropriate scaling of components for all frequency bins in the frequency space. Experiments verify a proper blind deconvolution of convolution mixtures of sources.

shading offers hope of dense depth measurements; however, it has to contend with the spatially varying albedo of the surface of the optic disk. Fortunately, we can control the lighting and positions of the stereo pair of cameras. Section 2 describes how we can exploit this degree of freedom to apply a technique akin to homomorphic filtering to separate the contribution of albedo and reflectance...

The performance of face recognition techniques is greatly challenged by the pose, expression and illumination of the image. For most existing systems, the recognition rate will decrease due to changes in environmental illumination. In this paper, a Homomorphic Wavelet-based Illumination Normalization (HWIN) method is proposed. The purpose of this method is to normalize the uneven illumination o...

The high incidence of breast cancer has increased significantly in the recent years. The most familiar breast tumors types are mass and microcalcifications (Mcs). Mammogram is considered the most reliable method in early detection of breast cancer. Computer-aided diagnosis system can be very helpful for radiologist in detection and diagnosing abnormalities earlier and faster than traditional sc...

A major obstacle to processing images of the ocean floor comes from the absorption and scattering effects of the light in the aquatic environment. Due to the absorption of natural light, underwater vehicles often require artificial light sources attached to them to provide the adequate illumination. Unfortunately, these flashlights tend to illuminate the scene in a nonuniform fashion, and, as t...