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Program Functions
159
vWarpManually
This function allows the user to manually warp an image. The result (deformed image or de-
formed ROI) is shown. At the beginning, the number of control points (in one direction) can
be selected. All control points are displayed. Then, the user selects one control point. The old
displacement value for this control point is shown and the user has to assign a new value. The
resulting displacement field is used to deform an image. There are two different modes. The
function can be called (from the File menu) to warp an atlas, which is then used instead of a
measured phase image. In this case, the atlas image is displayed and deformed. vWarpManu-
ally can also be called from the Tools menu to change the initial displacement field or to
change a resulting displacement field after the automatic warping has finished. Former could
be done to give the algorithm a good start displacement field; latter to improve the result.
vWarpUV.m
This function deforms an input image according to the displacement fields for all pixels (u and
v) by using the MATLAB function interp2. The interpolation method, e.g., bilinear interpola-
tion or nearest-neighbor interpolation, can be specified. Since this function is called often,
e.g., many times during the registration process, the function tries to use stored (persistent)
matrices that are needed as arguments for interp2 instead of recreating the matrices.
6.19 mrData (by Robert F. Dougherty)
mrData is a collection of relatively new tools for integrating MATLAB with a centralized MR
database. Robert F. Dougherty implemented it. In mrFindBorders, the function mrduigetfile of
the mrData collection is called. It allows searching a database for data, in the case of mrFind-
Borders especially for functional flat data, which is stored on remote servers. The files are
automatically downloaded into a temporary directory from which they can be accessed with
mrFindBorders.
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