Intergraph Raster

Intergraph Raster (INGR) is a raster graphics format associated with geospatial products from Intergraph.

Some sources mention a bi-level format named Intergraph File Format, Intergraph, IntergraphRLE, or ITG. It's not clear whether this refers to a particular type of INGR file, or to an entirely different file format.

Intergraph Raster is apparently distinct from Intergraph Standard File Formats (ISFF).

Identifiers
One source gives the following "partial listing" of INGR file extensions: .cot, .ctc, .rgb, .ctb, .grd, .crl, .tpe, .lsr, .rle, .cit, .g3, .g4, .tg4, .cmp, .jpg.

XnView also gives .itg.

LEADTOOLS also gives .t27, .t29.

PRONOM gives .ing.

Identification
The documentation implies that all INGR files begin with.

Specifications

 * Intergraph Raster File Format (from archive.org)
 * Intergraph Raster File Format Reference (formerly at ftp://ftp.intergraph.com/pub/bbs/scan/note/rffrgps.zip )

Software

 * GDAL
 * XnView
 * Image Alchemy

Links

 * GDAL: Intergraph Raster Format
 * LEADTOOLS: IntergraphRLE and Intergraph Raster File Formats
 * Intergraph