vpResample(3) Library Functions Manual vpResample(3) 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, ele- ment_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 res- olution. 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 cre- ate 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 di- mensions, specified by num_dimens. The sizes of the dimensions are speci- fied by src_dimens and dst_dimens which are 1D arrays with num_dimens ele- ments 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 re- sampling, so the scale factor is dst_dimens[0] / src_dimens[0]. The re- maining elements of src_dimens give the sizes of the other input array di- mensions in any order (although some orderings result in faster execution due to lower memory overhead). The other output array dimensions are ig- nored (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 el- ements 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) VolPack vpResample(3)
NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | ERRORS | SEE ALSO
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