Investigation on several methods to correct the intensity inhomogeneity in magnetic resonance images

Abstract

Magnetic resonance image (MRI) has opened up new avenues of diagnosis and treatment that were not previously available. However, there are a number of artifacts which can arise in the MRI process and make subsequent analysis more challenging. The most undesired visual effect is the intensity in-homogeneity in MRI. Therefore, study on correcting this in-homogeneity problem is essential to extract information from MRI correctly. In this project, we present three methods to correct the in-homogeneity in MRI which are histogram matching, histogram equalization, and homomorphic unsharp masking method. Histogram matching and histogram equalization are used to distribute the intensity of the input MRI uniformly. Another method which is homomorphic unsharp masking method functions as a sort of band notch filter, where a certain spatial frequency range in the image is selected and removed. It removes low frequency components from an image and it does not alter the tissue boundaries. This method is the simplest method and it can be done by using different kind of filter such as mean and median. From the result provided by the methods mention above, some methods do remove the in-homogeneity of MRI successfully while some methods do not. As a result, different methods do correct the in- homogeneity of the MRI in different ways.