This function obtains the identifier of the HDF GR raster image specified by its index.
Result = HDF_GR_SELECT(gr_id, index)
Returns the raster image identifier if successful or FAIL (-1) otherwise.
HDF GR interface identifier returned by HDF_GR_START.
Index of the raster image in the file. Valid values range from 0 to the total number of raster images in the file minus 1. The total number of the raster images in the file can be obtained by using HDF_GR_FILEINFO.