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)