Contrast enhancement of CT brain images for detection of ischemic stroke

The window setting allows the visualization of computed tomography (CT) brain images, and hence enables the detection of brain traumas such as ischemic stroke. However, the standard setting of window setting for CT brain images does not provide a good contrast to accentuate the hypodense area in the brain soft tissues. While the conventional histogram equalization (HE) and other proposed improvement schemes are not suitable to enhance the image contrast, a new method is presented in this paper to highlight the hypodense area for the detection of ischemic stroke. The presented method specifically enhances the contrast of soft tissues area and simultaneously preserves the background brightness, by eliminating the distribution of the extreme levels, normalizing the resulting distribution, and finally mapping the transform function on the image. Experimental results show that the presented method outperforms some existing improved HE method.