Selecting a threshold from the gradient histogram, a histogram of gradient magnitudes, of an image plays a crucial role in a gradient based edge detection system. This paper presents a methodology to determine the threshold from a gradient histogram generated using any kind of linear gradient operator on an image. We consider the image as a random process with dependent samples, model the gradi...

Contrast enhancement plays a fundamental role in image processing. Many histogram-based techniques are widely used for contrast enhancement of given images, due to their simple function and effectiveness. However, the conventional histogram equalization (HE) methods result in excessive contrast enhancement, which causes natural looking and satisfactory results for a variety of low contrast imag...

In this paper, a method for enhancing low contrast images is proposed. This method, called Gaussian Mixture Model based Contrast Enhancement (GMMCE), brings into play the Gaussian mixture modeling of histograms to model the content of the images. Based on the fact that each homogeneous area in natural images has a Gaussian-shaped histogram, it decomposes the narrow histogram of low contrast ima...

OBJECTIVE To assess (a) the correlations between magnetisation transfer ratio (MTR) histogram derived measures of the brain and the cervical cord from patients with different multiple sclerosis phenotypes and (b) the correlation between these metrics and clinical disability. Magnetisation transfer imaging is sensitive to the most destructive aspects of multiple sclerosis pathology. Magnetisatio...

In this short paper, a novel approach that combines global and local information to detect abrupt and gradual shot changes is proposed. In this approach, abrupt shot change is detected by an adaptive threshold computed from DC frame histogram difference with a sliding window. To detect gradual shot changes, this work performs an analysis of blockwise histogram difference with a statistical mode...

PURPOSE Investigating the diagnostic accuracy of histogram analyses of apparent diffusion coefficient (ADC) values for determining non-small cell lung cancer (NSCLC) tumor grades, lymphovascular invasion, and pleural invasion. MATERIALS AND METHODS We studied 60 surgically diagnosed NSCLC patients. Diffusion-weighted imaging (DWI) was performed in the axial plane using a navigator-triggered s...

The objects in the underwater images are not clearly visible due to low contrast and scattering of light and the large noise present in the environment. Hence it is difficult to segmentation in such environment without losing the details of the objects. In this paper a method of segmentation is presented for underwater images, in which the image quality is first enhanced using contrast limited ...

This paper presents an approach for human detection and simultaneous behavior recognition from images and image sequences. An action representation is derived by applying a clustering algorithm to sequences of Histogram of Oriented Gradient (HOG) descriptors of human motion images. For novel image sequences, we first detect the human by matching extracted descriptors with the prototypical actio...

The bimodality of a population P can be measured by dividing its range into two intervals so as to maximize the Fisher distance between the resulting two subpopulations P1 and P2. If P is a mixture of two (approximately) Gaussian subpopulations, then P1 and P2 are good approximations to the original Gaussians, if their Fisher distance if great enough. For a histogram having n bins this method o...

OBJECTIVE The purpose of this study was to compare the histogram analysis and visual scores in 3T MRI assessment of middle cerebral arterial wall enhancement in patients with acute stroke, for the differentiation of parent artery disease (PAD) from small artery disease (SAD). MATERIALS AND METHODS Among the 82 consecutive patients in a tertiary hospital for one year, 25 patients with acute in...