NIST IHead

File Format
Name	NIST IHead
Ontology	Electronic File Formats Graphics NIST IHead
Extension(s)	.pct
Released	≤1991

NIST IHead format (sometimes called IHDR) is a raster graphics format associated with some image databases published by NIST (National Institute of Standards and Technology). The databases are not generally available for free, but some sample files are.

IHead is not a very complex format, and it seems to be adequately documented. But it is still confusing, because every NIST database uses a different variant of it, and because everything associated with these databases seems to have multiple names.

The image may uncompressed, or use one of many compression algorithms. Compression code 0 means uncompressed, 2 is CCITT Group 4, and 6 is modified Lossless JPEG.

Identification

Some or all files begin with ASCII "288", followed by five 0x00 bytes. This is a decimal representation of the header size.

Software

• XnView
• The NIST databases and samples may include software (C source code) to read the format used in that database. For example, prints4.tar.Z includes an ihdr2sun.c file to convert to Sun Raster format.

Sample files

• Some of the files at ftp://sequoyah.ncsl.nist.gov/pub/databases/data/, such as prints4.tar.Z

Links

• NIST Special Database 4
  • prints4.txt - Information about NIST Special Database 4 - Fingerprint Samples
• NIST Special Database 14
  • prints14.txt - Information about Image Samples from NIST Special Database 14
• NIST Imaging Database 2 - Structured Forms Database Users' Guide (NIST Special Database 2), §2.2: Image File Format
• NIST Imaging Database 4 - Fingerprint Database (NIST Special Database 4)
• NIST Imaging Database 2 - Structured Forms Database Users' Guide (NIST Special Database 6)