BMP

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(→‎Windows BMP v3)
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|locfdd={{LoCFDD|fdd000189}}
 
|locfdd={{LoCFDD|fdd000189}}
 
|pronom={{PRONOM|fmt/116}}, others
 
|pronom={{PRONOM|fmt/116}}, others
 +
|released=~1987
 
}}
 
}}
 
'''BMP''' is a family of raster image file formats primarily used on Microsoft Windows and OS/2 operating systems. The format is sometimes known as '''Device-Independent Bitmap''' ('''DIB'''), since, when loaded into memory using Windows software, the image is held as a DIB structure.
 
'''BMP''' is a family of raster image file formats primarily used on Microsoft Windows and OS/2 operating systems. The format is sometimes known as '''Device-Independent Bitmap''' ('''DIB'''), since, when loaded into memory using Windows software, the image is held as a DIB structure.
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=== Windows BMP v2 ===
 
=== Windows BMP v2 ===
 
* Info header size: 12
 
* Info header size: 12
−
* Info header name: BITMAPCOREHEADER or OS21XBITMAPHEADER
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* Info header name: BITMAPCOREHEADER
 
* PRONOM: {{PRONOM|fmt/115}}
 
* PRONOM: {{PRONOM|fmt/115}}
  
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=== OS/2 BMP 1.0 ===
 
=== OS/2 BMP 1.0 ===
 
* Info header size: 12
 
* Info header size: 12
 +
* Info header name: BITMAPCOREHEADER or OS21XBITMAPHEADER
  
 
For practical purposes, OS/2 BMP 1.0 is identical to Windows BMP v2. But there is sometimes a small difference – see [[OS/2 BMP]] for details.
 
For practical purposes, OS/2 BMP 1.0 is identical to Windows BMP v2. But there is sometimes a small difference – see [[OS/2 BMP]] for details.
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* [http://wvnvms.wvnet.edu/vmswww/bmp.html Example BMP images (all Windows v3 except as indicated)]
 
* [http://wvnvms.wvnet.edu/vmswww/bmp.html Example BMP images (all Windows v3 except as indicated)]
 
* [http://entropymine.com/jason/bmpsuite/bmpsuite/html/bmpsuite.html BMP Suite Image List]
 
* [http://entropymine.com/jason/bmpsuite/bmpsuite/html/bmpsuite.html BMP Suite Image List]
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== See also ==
 +
* [[CUR]]
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* [[ICO]]
 +
* [[OS/2 BMP]]
 +
* [[Pocket PC Bitmap]]
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* [[Winzle Puzzle]]
  
 
== Resources ==
 
== Resources ==
−
* [http://en.wikipedia.org/wiki/BMP_%28file_format%29 BMP (file format): Wikipedia]
+
* [[Wikipedia:BMP file format|Wikipedia: BMP file format]]
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* [http://www.digitalpreservation.gov/formats/fdd/fdd000189.shtml Bitmap Image File (BMP), Version 5, from Library of Congress resource on Sustainability of Digital Formats]
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* {{EGFF|bmp|Microsoft Windows Bitmap File Format Summary}}, from the [[Encyclopedia of Graphics File Formats]]
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* [http://www.fileformat.info/format/bmp/egff.htm Microsoft Windows Bitmap File Format Summary] From Encyclopedia of Graphics File Formats at FileFormat.Info (1996)
+
−
* [http://www.fileformat.info/format/os2bmp/egff.htm OS/2 Bitmap File Format Summary] From Encyclopedia of Graphics File Formats at FileFormat.Info (1996)
+
  
 
[[Category:Microsoft]]
 
[[Category:Microsoft]]

Revision as of 14:15, 1 December 2014

File Format
Name BMP
Ontology
Extension(s) .bmp, .rle, .dib, .ddb
LoCFDD fdd000189
PRONOM fmt/116, others
Released ~1987

BMP is a family of raster image file formats primarily used on Microsoft Windows and OS/2 operating systems. The format is sometimes known as Device-Independent Bitmap (DIB), since, when loaded into memory using Windows software, the image is held as a DIB structure.

Though seemingly a simple format, it is complicated by its many different versions, lack of an official specification, lack of any version control process, and ambiguities and contradictions in the documentation.

Images are usually uncompressed, but RLE compression can be used under some conditions. JPEG, PNG, and Huffman 1D compression are also theoretically possible, but rarely supported.

Contents

Identifiers

No MIME type has been officially registered. Strings found in practice are: image/bmp; image/x-bmp; image/x-ms-bmp

The usual filename extension is .bmp. Extensions .rle (for RLE-compressed images) and .dib are also sometimes seen. Reportedly, .rl4 and .rl8 have also been used. The .dib extension sometimes means that the file lacks a file header. The .ddb extension is used only for v1 files.

Identification

The common types of BMP files almost always start with bytes 'B' 'M' ?? ?? ?? ?? 00 00 00 00.

However, some OS/2 BMP files contain nonzero "hotspot coordinates" at offset 6 to 9, even though these fields are not used in BMP format.

Well-known versions

BMP files (except for v1) use a common 14-byte file header, named BITMAPFILEHEADER. Following that is the "Info header", which begins with a 4-byte integer indicating its size. The Info header size (mostly) reveals the version of BMP that the file uses.

Windows BMP v2

  • Info header size: 12
  • Info header name: BITMAPCOREHEADER
  • PRONOM: fmt/115

See also OS/2 BMP 1.0, below.

Windows BMP v3

  • Info header size: 40
  • Info header name: BITMAPINFOHEADER
  • PRONOM: fmt/116, fmt/117

This is by far the most widely used version of BMP. It was introduced with Windows 3.x. Windows NT extended it to support 16 and 32 bits/pixel.

Windows CE also extended it, for example to allow 2 bits/pixel (see Pocket PC Bitmap), but its extensions were not migrated to the BMP v4 and v5 formats.

It is apparently possible for OS/2 BMP 2.0 format to masquerade as Windows BMP v3. The upshot is that if the compression type is 3 and the bit depth is 1, or the compression type is 4 and the bit depth is 24, then the file should be treated as OS/2 BMP 2.0.

Windows BMP v4

  • Info header size: 108
  • Info header name: BITMAPV4HEADER
  • PRONOM: fmt/118

Introduced with Windows 95. Adds support for transparency and colorimetry.

Windows BMP v5

  • Info header size: 124
  • Info header name: BITMAPV5HEADER
  • PRONOM: fmt/119

Introduced with Windows 98. Adds support for ICC profiles.

Other versions

Windows BMP v1

This is the bitmap file format used by Windows 1.0. It's not really a BMP format. It has a 10-byte file header, and is also called "DDB" (Device-Dependent Bitmap).

OS/2 BMP 1.0

  • Info header size: 12
  • Info header name: BITMAPCOREHEADER or OS21XBITMAPHEADER

For practical purposes, OS/2 BMP 1.0 is identical to Windows BMP v2. But there is sometimes a small difference – see OS/2 BMP for details.

OS/2 BMP 2.0

(see also OS/2 BMP)

  • Info header size: 16–64 (16, 40, 48, and 64 may be most common)
  • Info header name: BITMAPCOREHEADER2 or OS22XBITMAPHEADER
  • PRONOM: x-fmt/270

OS/2 BMP 2.0 defines several file subtypes; here we are describing only the "Bitmap" subtype (files with a signature of "BM"). For other subtypes, see OS/2 BMP.

The header size can be reduced from its full size of 64 bytes. Omitted fields are assumed to have a value of zero.

The fields in the first 40 bytes of the header are (nearly) identical to those in Windows BMP v3, v4, and v5. The remaining fields are different.

OS/2 BMP 2.0 supports compression types "Huffman 1D" and "RLE24", unlike any other version of BMP.

BITMAPV2INFOHEADER

  • Info header size: 52
  • Info header name: BITMAPV2INFOHEADER

No details known.

BITMAPV3INFOHEADER

  • Info header size: 56
  • Info header name: BITMAPV3INFOHEADER

No details known.

Symbol definitions

Here are the definitions, from the Windows SDKs, of some of the symbols used in the BMP documentation.

All integers use little-endian byte order.

Symbol Definition
WORD unsigned 16-bit integer
DWORD unsigned 32-bit integer
LONG signed 32-bit integer
BI_RGB 0
BI_RLE8 1
BI_RLE4 2
BI_BITFIELDS 3
(Huffman 1D) 3
BI_JPEG 4
(24-bit RLE) 4
BI_PNG 5
BI_ALPHABITFIELDS 6
BI_SRCPREROTATE 0x8000 (?)
LCS_CALIBRATED_RGB 0
LCS_sRGB 'sRGB' = 0x73524742
LCS_WINDOWS_COLOR_SPACE 'Win ' = 0x57696e20
PROFILE_LINKED 'LINK' = 0x4c494e4b
PROFILE_EMBEDDED 'MBED' = 0x4d424544
LCS_GM_BUSINESS 1
LCS_GM_GRAPHICS 2
LCS_GM_IMAGES 4
LCS_GM_ABS_COLORIMETRIC 8

Specifications

Sample files

Windows BMP v2

This format is fairly common, but examples of it can be hard to spot amidst all the BMPv3 files.

Windows BMP v3

OS/2 BMP 2.0

Refer to OS/2 BMP.

Various

See also

Resources

Retrieved from "http://fileformats.archiveteam.org/index.php?title=BMP&oldid=19824"
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