Indonesian Journal of Electrical Engineering and Computer Science Vol. 28, No. 2, November 2022, pp. 762~768 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v28.i2.pp762-768  762 Journal homepage: http://ijeecs.iaescore.com Multi-modal image fusion using contourlet and wavelet transforms: a multi-resolution approach Bhavana V. 1 , Krishnappa H. K. 2 1 Department of Electronics and Communication Engineering, Amrita School of Engineering, Bengaluru, Amrita Vishwa Vidyapeetham, India 2 Department of Computer Science and Engineering, R V College of Engineering, Visvesvaraya Technological University, Bengaluru, India Article Info ABSTRACT Article history: Received Feb 10, 2022 Revised Aug 13, 2022 Accepted Aug 24, 2022 In recent years, vast improvement and progress has been observed in the field of medical research, especially in digital medical imaging technology. Medical image fusion has been widely used in clinical diagnosis to get valuable information from different modalities of medical images to enhance its quality by fusing images like computed tomography (CT), and magnetic resonance imaging (MRI). MRI gives clear information on delicate tissue while CT gives details about denser tissues. A multi-resolution approach is proposed in this work for fusing medical images using non-sub-sampled contourlet transform (NSCT) and discrete wavelet transform (DWT). In this approach, initially the input images are decomposed using DWT at 4 levels and NSCT at 2 levels which helps to protect the vital data from the source images. This work shows significant enhancement in pixel clarity and preserves the information at the corners and edges of the fused image without any data loss. The proposed methodology with an improved entropy and mutual information helps the doctors in better clinical diagnosis of brain diseases. Keywords: Computed tomography Discrete wavelet transform Image fusion Magnetic resonance imaging Non-sub-sampled contourlet transform This is an open access article under the CC BY-SA license. Corresponding Author: Bhavana V. Department of Electronics and Communication Engineering, Amrita School of Engineering Bengaluru, Amrita Vishwa Vidyapeetham, India Email: bhavanapyarilal@gmail.com 1. INTRODUCTION In the field of medicine, preserving both the spectral and spatial qualities in a single image is significantly essential for the radiologists for various purposes like research, and treatment process. Computed tomography (CT) image is the most popular for displaying the structure of the bones and is deficient with the information about tissues, whereas magnetic resonance imaging (MRI) offers data about soft tissues. Information from both the modalities of images are required to assist the medical experts for precise and accurate diagnosis. Image fusion is the technique of combining two image modalities into a single image with detailed information without delivering subtle elements. Vitally, it is used in the areas of medical imaging, remote sensing, and autonomy. The procedure of image fusion involves extracting a larger amount of data from each of the given input images in a single frame. Image fusion techniques are categorized into two domains namely, a) Spatial domain b) Transform domain Image pixels are specifically managed in spatial domain analysis. The pixel quality of the image is specifically monitored to realize the desired outcome.