Convert NII to JPG Online
Cannot open a .nii file on your computer? NII is the file extension for NIfTI neuroimaging format, widely used in brain research and clinical neurology. Our converter extracts 2D slices from .nii 3D brain volumes and saves them as standard JPG images that you can view, share, and present on any device — without installing FSL, FreeSurfer, or other neuroimaging software.
Dosyanızı buraya sürükleyin
DICOM (.dcm), NIfTI (.nii, .nii.gz), NRRD (.nrrd), MHA (.mha)
Max file size: 200 MB • Processed locally
Why Convert NII to JPG?
Files with the .nii extension are NIfTI format neuroimaging data — 3D brain volumes that standard image viewers cannot open. If you received .nii files from a research collaborator, downloaded brain atlas data, or need to view results from a neuroimaging analysis pipeline, converting to JPG gives you instant visual access. JPG is the most universally supported image format, viewable on every computer, phone, and tablet without any special software.
Neuroscience students and early-career researchers often encounter .nii files before they have fully configured their analysis workstations. Instead of spending hours installing and configuring FSL, FreeSurfer, or SPM, a quick NII-to-JPG conversion lets you immediately see the imaging data and verify that you have the correct files before investing in full pipeline setup.
For lab meetings, thesis committees, and interdisciplinary project updates, JPG images from .nii brain scans can be directly embedded in presentation slides, shared via email, or posted to lab wikis — making neuroimaging results accessible to team members from diverse technical backgrounds.
How to Convert NII to JPG
- Upload your .nii file from a research pipeline, atlas download, or collaborator.
- The converter reads the NIfTI header and extracts slices with correct orientation.
- Download JPG images of brain scan slices — viewable on any device.
Key Features
- Open .nii files without neuroimaging software installation
- Automatic 3D volume slicing with anatomical orientation
- Compatible with all standard NIfTI neuroimaging data
- Works with brain atlases, structural MRI, and fMRI data
- JPG output viewable on any device and insertable in presentations
- Free online tool — no account or registration needed
- Secure processing with automatic file deletion
Frequently Asked Questions
What is a .nii file?
A .nii file is a NIfTI (Neuroimaging Informatics Technology Initiative) format file containing 3D or 4D brain imaging data. It is the standard format used in neuroscience research for MRI, fMRI, DTI, and other brain imaging modalities. The .nii extension is used for uncompressed NIfTI files, while .nii.gz is the gzip-compressed variant.
Can I convert .nii.gz files too?
For gzip-compressed NIfTI files (.nii.gz), please use our dedicated NII.GZ to JPG converter which handles the decompression step automatically. This page handles uncompressed .nii files directly.
How do I know which slice to use for my presentation?
Our converter extracts the middle slice from each anatomical plane (axial, sagittal, coronal) by default. These typically show the most anatomically informative views. For specific slice selection, use FSLeyes to identify the desired slice coordinates first.
Will the conversion work with brain atlas files?
Yes. Our converter handles standard NIfTI atlas files (MNI152, AAL, Harvard-Oxford) and outputs properly oriented JPG slices. Atlas labels stored as integer values in the volume are rendered as a grayscale image.