Tumor Is An Uncontrolled Growth Of Tissue In Any Part Of The Body. The Tumor Is Of Different Types And Has Different Characteristics And Corresponding Different Treatment. If We Find The Tumor In Early Stages, We Can Stop Further Growth Of The Tumor And Proper Treatment Is Undergone For The Tumor. Magnetic Resonance Imaging (MRI) Is The Most Important Techniqu1e, In Discovering The Brain Tumor. This MRI Image Is Visually Examined By The Physician For Detection & Diagnosis Of Brain Tumor. Due To Complex Appearance In MRI, Brain Tumor Texture Is Formulated Using A Multiresolutionfractal Model Known As Multifractional Brownian Motion (mBm). Detailed Mathematical Derivation For MBm Model And Corresponding Novel Algorithm To Extract Spatially Varying Multifractal Features Are Proposed.