FIG. 2.
A: Shows the distribution of compression factors for 280 groups through the GRM process. The compression factor is the ratio of the number of dictionary elements in the group against the number of singular vectors retained using a 10−5 relative truncation tolerance. B: Shows the number of groups that each voxel will need to be evaluated against after the GRM pruning stage. The inclusion of groups for matching consideration is based upon a relative truncation level of 5 × 10−3 below the best group mean signal correlation for each voxel. C: Shows the condition number for the group mean signals assuming varying group sizes. As the number of groups increases the linear independence of the group signals is degraded. D: shows the average compression rate across the group PCA, where smaller group sizes are less likely to be highly compressible.