Skip to main content
Service phase: Beta

This service is still in development. Give us your feedback.

Format

OS/2 Bitmap

Download XML Download JSON

Summary

Name
OS/2 Bitmap
Version
2.0
Identifiers
  • MIME: image/bmp
  • PUID: x-fmt/270
Format type
Image (Raster)
Description
This is an outline record only, and requires further details, research or authentication to provide information that will enable users to further understand the format and to assess digital preservation risks associated with it if appropriate. If you are able to help by supplying any additional information concerning this entry, please return to the main PRONOM page and select ‘Add an Entry’.
Format encoding
Text
File extensions
bmp
Submitted by
Digital Preservation Department / The National Archives

Internal signatures

OS/2 Bitmap 2.0

Description
2-byte file type identifier ASCII “BM” at beginning of a 14-byte file header; offset 14 little-endian long integer size of bitmap header (16, 64); offset 26 2-byte little-endian number of bit planes (always 1). The 2 byte file type identifier BM indicates that the BMP was created by OS/2 or Windows. Windows 3.x, Windows NT, and OS/2 2.x BMP files only vary in the number of fields in the bitmap header and in the interpretation of the compression field. Bitmap headerSize is 12 for Windows 2.x BMP and OS/2 1.x BMP, 40 for Windows 3.x and Windows NT BMP, 12 to 64 for OS/2 2.x BMP, and 108 for Windows 4.x BMP. Only OS/2 2.x bitmaps have Bitmap header size of 16 and 64. If Bitmap header size is 40, only OS/2 Bitmaps can use 24-bit RLE compression on 24-bit pixel bitmaps and only oS/2 bitmaps can use Huffman 1D compression on 1-bit per pixel (monochrome) bitmaps.
Provenance
Signature identified by Georgia Tech Research Institute

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
None
Byte Sequence
424D{12}(10|30|40)000000{8}0100
Endianness
None

OS/2 Bitmap 2.0 (24-bit RLE compression)

Description
2-byte magic number ASCII “BM” at beginning of a 14-byte file header; offset 14 little-endian long integer size of bitmap header (40); offset 26 2-byte little-endian number of bit planes (always 1); offset 28 24-bits per pixel (1800); offset 30 Compression type 24-bit RLE (0400).
Provenance
Signature identified by Georgia Tech Research Institute

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
None
Byte Sequence
424D{12}28000000{8}0100180004000000
Endianness
None

OS/2 Bitmap 2.0 (Huffman 1D compression)

Description
2-byte magic number ASCII “BM” at beginning of a 14-byte file header; offset 14 little-endian long integer size of bitmap header (40); offset 26 2-byte little-endian number of bit planes (always 1); offset 28 1-bit perpixel (0100); offset 30 huffman 1D compression (0300)
Provenance
Signature identified by Georgia Tech Research Institute

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
None
Byte Sequence
424D{12}28000000{8}0100010003000000
Endianness
None

Changelog

  • V51

    Release date
    15 July 2011

    • Added signature

      OS/2 Bitmap 2.0: Signatures submitted by Georgia Tech Research Institute, USA.