More and more people suffer from fatty liver disease in the world even without hepatitis infections or alcoholic intake. In this paper, we propose to carry out a magnetic resonance imaging (MRI) fat ratio reconstruction on ImageJ to analyze the MRI output images. Post processing methods include image histogram, calculator, mathematic, 3D surface plot, and histogram analysis. Mode value of histogram analysis from a patient who undergoes fatty liver treatment was displayed before and after treatment. With mode value display, the fat ratio decrease after fatty liver therapy. The patient blood test with alanine transaminase levels also decrease. With the mode value display of the liver, we can objectively display the fat ratio of the whole liver in a 2-dimensional image using the DIXON or the IDEAL methods.