Soft shadows and penumbra regions generated by extended light sources such as linear and area lights are visual effects that significantly contribute to the realism of a scene. In interactive applications, shadow computations are mostly performed by either the shadow volume or the shadow map algorithm. Variants of these methods for soft shadows exist, but they require a significant number of sa...

A method is explored to remove tall building shadows in true color and color infrared urban aerial images based on the theory of color constancy. This paper first uses the specthem ratio and Otsu threshold segmentation methods to detect building shadows on urban aerial true color and color infrared aerial images. Then, based on the shadow detection result, one of the color constancy algorithms ...

As most local recurrence after breast-conserving treatment occurs within 2 cm around the lumpectomy cavity, wide-volume partial breast rather than whole breast irradiation has been actively investigated with a view to decreasing radiation toxicities. Replacing external beam radiotherapy by wide-volume interstitial brachytherapy offers the advantages of more accurate treatment volume coverage an...

In this paper, we present a fuzzy Markovian method for brain tissue segmentation from magnetic resonance images. Generally, there are three main brain tissues in a brain dataset: gray matter, white matter, and cerebrospinal fluid. However, due to the limited resolution of the acquisition system, many voxels may be composed of multiple tissue types (partial volume effects). The proposed method a...

We present a novel fuzzy region-based hidden Markov model (frbHMM) for unsupervised partial-volume classification in brain magnetic resonance images (MRIs). The primary contribution is an efficient graphical representation of 3D image data in which irregularly-shaped image regions have memberships to a number of classes rather than one discrete class. Our model groups voxels into regions for ef...

This paper addresses the problem of accurate voxel-level estimation of tissue proportions in the human brain magnetic resonance imaging (MRI). Due to the finite resolution of acquisition systems, MRI voxels can contain contributions from more than a single tissue type. The voxel-level estimation of this fractional content is known as partial volume coefficient estimation. In the present work, t...