S3DL (Subject Specific Sparse Dictionary Learning) is a software tool to generate whole brain segmentation as well as lesion segmentation from multi-contrast human brain MR images. It is a patch-based method, where similarities between patches from a subject and one or more atlases are exploited to create a segmentation of the subject.

There are two parts of the tool, one to create multi-class segmentation from T1-w MR images, another to segment MS lesions from T1-w and FLAIR images. They can be used independently. In addition to the software, some training atlases and test data are provided.

The toolbox is based on the following paper,
S. Roy, Q. He, E. Sweeney, A. Carass, D. S. Reich, J.L. Prince, and D. L. Pham, "Subject-Specific Sparse Dictionary Learning for Atlas-Based Brain MRI Segmentation", IEEE Journal of Biomedical and Health Informatics, 19(5):1598-1609, 2015.