NAME

       vpResample, vpResample2D, vpResample3D - resample an array

SYNOPSIS

       #include <volpack.h>

       vpResult
       vpResample(vpc,  num_dimens,  src_dimens,  dst_dimens, src_strides, dst_strides, element_type, src_array,
               dst_array)
           vpContext *vpc;
           int num_dimens;
           int *src_dimens, *dst_dimens;
           int *src_strides, *dst_strides;
           int element_type;
           void *src_array, *dst_array;

       vpResult
       vpResample2D(src_array, src_x, src_y, dst_array, dst_x, dst_y, element_type, filter_type)
           void *src_array;
           int src_x, src_y;
           void *dst_array;
           int dst_x, dst_y;
           int element_type;
           int filter_type;

       vpResult
       vpResample3D(src_array, src_x, src_y, src_z, dst_array, dst_x, dst_y, dst_z, element_type, filter_type)
           void *src_array;
           int src_x, src_y, src_z;
           void *dst_array;
           int dst_x, dst_y, dst_z;
           int element_type;
           int filter_type;

ARGUMENTS

       vpc    VolPack context from vpCreateContext.

       num_dimens
              Number of dimensions in the input and output arrays.

       src_dimens
              Array containing the dimensions of the input array.

       dst_dimens
              Array containing the dimensions of the output array.

       src_strides
              Array containing the strides for each dimension of the input array.

       dst_strides
              Array containing the strides for each dimension of the output array.

       element_type
              Constant specifying the data type of the array elements (VP_UCHAR, VP_USHORT, VP_FLOAT).

       src_array
              Input array containing input data.

       dst_array
              Output array for result data.

       src_x, src_y, src_z
              Dimensions of the input array.

       dst_x, dst_y, dst_z
              Dimensions of the result array.

       filter_type
              Constant  specifying   one   of   the   predefined   filters   (VP_BOX_FILTER,   VP_LINEAR_FILTER,
              VP_GAUSSIAN_FILTER, VP_BSPLINE_FILTER, VP_MITCHELL_FILTER).

DESCRIPTION

       vpResample  is  used  to  resample an array to a new grid with a different resolution.  It can be used to
       scale up or decimate an array of volume data,  for  instance.   An  arbitrary  separable  space-invariant
       resampling  filter  can  be  specified via a lookup table containing filter weights.  The input array may
       have an arbitrary number of dimensions, but on each call to vpResample only one dimension of the array is
       resampled.  To scale all dimensions call the routine once for each dimension.  Transformations other than
       scales (e.g. rotations and shears) are not supported by these routines.

       The routines vpResample2D and vpResample3D provide a simpler (but less flexible) interface to vpResample.
       They  take  as  arguments  an input array with its dimensions, an output array with its dimensions, and a
       constant specifying a filter.  The input array is resampled once for each dimension and  then  stored  in
       the output array.  These two routines automatically create a filter weight table and arrays for temporary
       results.

       The remainder of this man page describe vpResample.  The vpc argument is a VolPack context that  contains
       a  description  of  the  resampling  filter.   Use vpSetFilter to define the filter.  The volume data and
       rendering parameters currently stored in the context are not affected by calls to vpResample.

       The remaining arguments to vpResample describe the size and layout of the input and output  arrays.   The
       two arrays must have the same number of dimensions, specified by num_dimens.  The sizes of the dimensions
       are specified by src_dimens and dst_dimens which are 1D arrays with num_dimens elements  in  each  array.
       src_dimens[0]  is  the  size  of  the  input dimension to be resampled.  dst_dimens[0] is the size of the
       output dimension after resampling, so the scale factor is dst_dimens[0] / src_dimens[0].   The  remaining
       elements  of  src_dimens  give  the sizes of the other input array dimensions in any order (although some
       orderings result in faster execution due to lower memory overhead).  The other  output  array  dimensions
       are  ignored (although they should be the same as the corresponding input array dimensions since only one
       dimensions is resampled).

       The src_strides and dst_stride arguments are 1D arrays that contain a stride in bytes for each  dimension
       of the input and output arrays, stored in the same order as the dimensions sizes in src_dimens.

       The  element_type  argument  specifies the data type of each element of the input and output data arrays.
       The supported types are:

       VP_UCHAR
              Unsigned character (1 byte per element).

       VP_USHORT
              Unsigned short (2 bytes per element).

       VP_FLOAT
              Single-precision floating point (4 bytes per element).

       Finally, the last two arguments to vpResample are pointers to the first elements of the input and  output
       arrays.

ERRORS

       The normal return value is VP_OK.  The following error return values are possible:

       VPERROR_BAD_SIZE
              No filter weight table has been specified.

SEE ALSO

       VolPack(3), vpSetFilter(3)