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MINC variable types

Medical imaging tends to produce files with a large amount of ancillary data (patient information, image information, acquisition information, etc.). To organise this information in a useful fashion, MINC uses variables to group together related attributes. The variable itself may or may not contain useful data. For example, the variable MIimage contains the image data and has attributes relevant to this data. The variable MIpatient has no relevant variable data, but serves to group together all attributes describing the patient (name, birthdate, etc.). This sort of variable is called a group variable.

Variables that correspond to dimensions are called dimension variables and describe the coordinate system corresponding to the dimension. An example is MIxspace -- both a dimension and a variable describing the x coordinate of other variables.

The NetCDF conventions allow for these dimension variables to specify the coordinate at each point, but there is nothing to describe the width of the sample at that point. MINC provides the convention of dimension width variables, e.g. MIxspace_width, to give this information.

Finally, it is possible to have attributes that vary over some of the dimensions of the variable. For example, if we have a volume of image data, varying over MIxspace, MIyspace and MIzspace, we may want an attribute giving the maximum value of the each image, varying over MIzspace. To achieve this we use a variable, called a variable attribute, pointed to by an attribute of the image variable.

Thus MINC introduces a number of types of variables: group variables, dimension variables, dimension width variables and variable attributes.


next up previous contents
Next: Data organization Up: The MINC standard Previous: The MINC standard   Contents
Robert VINCENT 2004-05-28