Soma-IO provides a new IO system: soma::Reader, soma::Writer etc. Their implementation for volumes support partial reading/writing features (depending on the format).

These partial IO may be speficied in options, or in the file name URL, in the following manner:

Reading:

"filename.nii.gz?ox=30&sx=50&oy=40&sy=100" reads a view in the NIFTI file filename.nii.gz, with the origin (in AIMS coordinates) at (30, 40, 0, 0), with the view size (50, 100, ?, ?) (? being the whole volume size).

Writing:

"filename.ima?partial_writing=1&ox=30&oy=40" will write the volume in memory as a part of a larger, existing file, filename.ima, at position (30, 40, 0, 0) in it.

To save a part of the volume in memory, you have to make a view in it (as a secondary volume) and save this view.

Such URL syntax is supported in the Soma-IO system implementation for volumes, so will be used for every format. Some formats may or may not use these options, however.

In AIMS, Soma-IO is used alternately, and in addition to the former AIMS IO system, which does not support such URL options. So the result will actually depend on whether the IO format is implemented in the Soma-IO or the AIMS layer.

For formats implemented in the Soma-IO layer, such options will be available with every reader/writer or progrem: anatomist, AimsFileConvert, or the AIMS python API (aims.read() etc).

Allocation:

The IO system (both in AIMS and Soma-IO) can make use of soma::AllocatorContext hints to allocate data. See the details in Soma-IO Reader and Writer section.