Compression is applied on a per-dataset basis in HDF5 files, therefore it is possible to compress certain datasets and leave others uncompressed. As a simplification the MINC 2.0 library will apply the same compression algorithm to all of the image data in a file, and will not support compression of other datasets.
When compression is enabled in HDF5, the compressed dataset must be stored using the chunked layout. Chunked datasets are stored in a series of blocks which have the same dimensionality as the dataset. This storage method may improve average data access times for certain image processing algorithms, and so the MINC 2.0 library allows chunking to be specified without requiring compression.