Class FileMGH


  • public class FileMGH
    extends FileBase
    The class reads MGH files. The 4 by 4 matrix in MGH transforms x,y,z indexes to (right, anterior, superior) coordinates where +x = Right, +y = Anterior, +z = Superior. In MIPAV the 4 by 4 matrix does not imply the axis orientations.

    The MGH definition is: [right] = [xr yr zr] [ xsize * x] + [rorigin] [anterior] = [xa ya za] [ ysize * y] + [aorigin] [superior] = [xs ys zs] [ zsize * z] + [sorigin] Now in going to MIPAV a change must occur. MGH has L->R and P->A while MIPAV uses R->L in all axes and A->P in axes 0 and 1 and P->A in axis 2, so this would cause xr, yr, zr, rorigin, xa, ya, za, and aorigin to be multiplied by -1. cr, ca, and cs refer to the center point of the scanner coordinate system.

    A 284 byte header always precedes the data buffer In version 1 if the goodRASFlag 0, then the first 90 bytes are read

    Immediately after the data buffer other optional data structures may be found: They are: Recovery time in milliseconds float Flip angle in radians float Echo time in milliseconds float Inversion time in millseconds float Field of view in millimeters float Comment about fov field from Nick Schmansky: The FoV field should be ignored. In discussing this field with Bruce Fischl, and looking more closely at the code, it appears to be a field with a long and inconsistent usage history (in how it is set and where the data originates). We do not rely on it in our binaries. Lastly, tags including the Talairach transform file name and a list of commands used to create this data(provenance info) may be present.

    I am not reading the contents of the Talairach transform file for 3 reasons: 1.) This information is probably not very useful. 2.) Every sample file that I obtained from MGH gave the same name: talairach.xfm. If this name is always used, then it is impossible to tell which .mgh file it corresponds to. 3.) The Talairach transform file is a clear ascii file, so it can be easily read with any number of common programs.

    See Also:
    FileIO, FileInfoMGH, FileRaw
    • Field Detail

      • TAG_OLD_COLORTABLE

        private static final int TAG_OLD_COLORTABLE
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        See Also:
        Constant Field Values
      • TAG_OLD_USEREALRAS

        private static final int TAG_OLD_USEREALRAS
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        See Also:
        Constant Field Values
      • TAG_OLD_SURF_GEOM

        private static final int TAG_OLD_SURF_GEOM
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        See Also:
        Constant Field Values
      • TAG_OLD_MGH_XFORM

        private static final int TAG_OLD_MGH_XFORM
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        See Also:
        Constant Field Values
      • cmdlines

        java.lang.String[] cmdlines
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      • ncmds

        int ncmds
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      • axisOrientation

        private int[] axisOrientation
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      • bytesPerValue

        private int bytesPerValue
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      • ca

        private float ca
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      • cr

        private float cr
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      • cs

        private float cs
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      • dataType

        private int dataType
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      • depth

        private int depth
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      • dof

        private int dof
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      • extents

        private int[] extents
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      • file

        private java.io.File file
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      • fileDir

        private java.lang.String fileDir
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      • fileLength

        private long fileLength
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      • fileName

        private java.lang.String fileName
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      • fis

        private java.io.FileInputStream fis
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      • flipAngle

        private float flipAngle
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      • fov

        private float fov
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      • goodRASFlag

        private short goodRASFlag
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      • gunzip

        private boolean gunzip
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      • height

        private int height
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      • mghType

        private int mghType
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      • nFrames

        private int nFrames
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      • optionalStructuresLocation

        private long optionalStructuresLocation
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      • origin

        private float[] origin
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      • resolutions

        private float[] resolutions
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      • te

        private float te
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      • ti

        private float ti
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      • tr

        private float tr
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      • version

        private int version
        Present version number is 1.
      • width

        private int width
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      • xa

        private float xa
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      • xr

        private float xr
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      • xs

        private float xs
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      • ya

        private float ya
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      • yr

        private float yr
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      • ys

        private float ys
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      • za

        private float za
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      • zr

        private float zr
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      • zs

        private float zs
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    • Constructor Detail

      • FileMGH

        public FileMGH​(java.lang.String fName,
                       java.lang.String fDir)
        Constructs new file object.
        Parameters:
        fName - File name.
        fDir - File directory.
    • Method Detail

      • finalize

        public void finalize()
        Prepares this class for cleanup. Calls the finalize method for existing elements, closes any open files and sets other elements to null.
        Overrides:
        finalize in class FileBase
      • getFileInfo

        public FileInfoMGH getFileInfo()
        Returns the FileInfoMGH read from the file.
        Returns:
        File info read from file, or null if it has not been read.
      • readHeader

        public boolean readHeader​(java.lang.String imageFileName,
                                  java.lang.String fileDir)
                           throws java.io.IOException
        Reads the MGH header and stores the information in fileInfo.
        Parameters:
        imageFileName - File name of image.
        fileDir - Directory.
        Returns:
        Flag to confirm a successful read.
        Throws:
        java.io.IOException - if there is an error reading the header
        See Also:
        FileInfoMGH
      • readImage

        public ModelImage readImage​(boolean one)
                             throws java.io.IOException,
                                    java.lang.OutOfMemoryError
        Reads a MGH image file by reading the header then making a FileRaw to read the image for all filenames in the file list. Only the one file directory (currently) supported.
        Parameters:
        one - flag indicating one image of a 3D dataset should be read in.
        Returns:
        The image.
        Throws:
        java.io.IOException - if there is an error reading the file
        java.lang.OutOfMemoryError
        See Also:
        FileRaw
      • readImage

        public void readImage​(float[] buffer)
                       throws java.io.IOException,
                              java.lang.OutOfMemoryError
        Reads a MGH image file by reading the header then making a FileRaw to read the file. Image data is left in buffer. If the fileInfo cannot be found, the header will be located and read first. Image is not 'flipped', and neither units of measure nor orientation are set.
        Parameters:
        buffer - Image buffer to store image data into.
        Throws:
        java.io.IOException - if there is an error reading the file
        java.lang.OutOfMemoryError
        See Also:
        FileRaw
      • writeImage

        public void writeImage​(ModelImage image,
                               FileWriteOptions options)
                        throws java.io.IOException
        Writes a MGH or MGZ format type image.
        Parameters:
        image - Image model of data to write.
        options - options such as starting and ending slices and times
        Throws:
        java.io.IOException - if there is an error writing the file
      • attachFileInfo

        private void attachFileInfo​(FileInfoMGH fileInfo,
                                    ModelImage image)
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        Parameters:
        fileInfo - -- a NIFTI file Info that has already been read
        image - -- a ModelImage that the fileInfo needs to be attached to
      • getAxisOrientation

        public static int[] getAxisOrientation​(TransMatrix mat)
        Return the 3 axis orientation codes that correspond to the closest standard anatomical orientation of the (i,j,k) axes.
        Parameters:
        mat - 4x4 matrix that transforms (i,j,k) indexes to x,y,z coordinates where +x =Left, +y = Posterior, +z = Superior Only the upper-left 3x3 corner of the matrix is used This routine finds the permutation of (x,y,z) which has the smallest angle to the (i,j,k) axes directions, which are columns of the input matrix Errors: The codes returned will be zero.
        Returns:
        DOCUMENT ME!
      • getOffset

        private int getOffset()
        Helper method to calculate the offset for getting only the middle NIFTI image slice from the 3D file.
        Returns:
        offset
      • updateorigins

        private void updateorigins​(FileInfoBase[] fileInfo)
        Updates the start locations. Each image has a fileinfo where the start locations are stored. Note that the start location for the Z (3rd) dimension change with the change is the slice. The origin is in the upper left corner and we are using the right hand rule. + x -> left to right; + y -> top to bottom and + z -> into screen.
        Parameters:
        fileInfo - DOCUMENT ME!