PURPOSE To determine the significance of vascular enhancement in stroke patients with and without permanent neurologic deficit. METHODS We prospectively studied two groups of patients with spin-echo MR imaging before and after injection of gadopentetate dimeglumine. In the patients in group 1 (12 women, 22 men; age range, 32 to 76 years), who had permanent neurologic deficit caused by recent ...

R Cromartie! and S M Pizerl,2 1 Department of Computer Science 2Departments of Radiology and Radiation Oncology The University of North Carolina at Chapel Hill Chapel Hill, N.C. 27599 Contrast enhancement is a fundamental step in the display of digital images. The end result of display is the perceived brightness occurring in the human observer; design of effective contrast enhancement mappings...

The rapid introduction of direct and indirect digital imaging systems in natural images has created a wide selection of computer-based methods for analyzing imaging. Utilizing the computational power along with the application of digital imaging algorithms, has a significant impact on analyzing utility. It is crucial to understand the mechanisms by which a given imaging algorithm modifies an im...

We presents results obtained by different contrast enhancement methods applied to medical images. We take into account classical histogram specification, local and wavelet-based techniques and a novel approach for multiscale contrast enhancement. The latter, whose rationale grounds in theories of visual perception, exploits a local definition of the Fechner-Weber’s contrast within the context o...

The contrast of photographs or rendered images is commonly enhanced to increase the image’s visual appeal. Normal computer science approaches take no account of image content. In artwork, spatial configurations are use to increase apparent contrast. We have a spatially aware contrast enhancement algorithm, which uses image structure to hide the countershading profiles. We can achieve enhancemen...

A novel image contrast enhancement (ICE) circuit was proposed by modulating the reference voltages of the source driver circuit in liquid-crystal displays (LCDs). The adjustment of reference voltages is achieved immediately by applying external adjustment codes, which may be generated in accordance with the video data distribution on image displays and the liquid crystal materials, and leads to...

A novel algorithmic approach for optimal contrast enhancement is proposed. A measure of expected contrast and a sister measure of tone subtlety are defined for gray level transform functions. These definitions allow us to depart from the current practice of histogram equalization and formulate contrast enhancement as a problem of maximizing the expected contrast measure subject to a limit on to...

Almost every branch of medical imaging uses the concept of digital image processing for visualizing and extracting details from the data images. Thus, quality enhancement has become more important to be performed with the help of various techniques. The enhancement of an image is one of the most acceptable methods to get the deeper knowledge of any image. There are various contrast enhancement ...

A novel undecimated wavelet transform based contrast enhancement algorithmisproposed to for both gray scale andcolor images. Contrast enhancement is realized by tuning the magnitude of approximation coefficients at each level with respect to the approximation coefficients of one higher level during the inverse transform phase in a center/surround enhancement sense.The performance of the propose...

In this work we propose a discussion and detailed implementation of a very simple gradient domain method that tries to eliminate the effect of nonuniform illumination and at the same time preserves the images details. This model, which to the best of our knowledge has not been explored in spite of its simplicity, acts as a high pass filter. We show that with a single contrast parameter (which k...