Routines (alphabetical) > Routines: H > HDF Routines > HDF_GR_REFTOINDEX

# HDF_GR_REFTOINDEX

This function returns the index of the HDF GR raster image specified by the parameter gr_ref.

## Syntax

Result = HDF_GR_REFTOINDEX(gr_id, gr_ref)

## Return Value

Returns the index of the image if successful or FAIL (-1) otherwise.

## Arguments

### gr_id

HDF GR interface identifier returned by HDF_GR_START.

### gr_ref

Reference number of the raster image.

## Keywords

None

## Version History

5.2 | Introduced