OS/2 bitmap family
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|<code>PT</code> || Pointer || Refer to [[OS/2 Pointer]]. | |<code>PT</code> || Pointer || Refer to [[OS/2 Pointer]]. | ||
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| + | == OS/2 BMP vs. Windows BMP == | ||
| + | OS/2 BMP 1.0 and Windows BMP v2 are sometimes said to be identical, but apparently that's not quite true. In OS/2 BMP formats, the "Size" field at offset 2 (variously named "cbSize", "FileSize", or "bfSize") is supposed to equal the size of the headers (always 26 for OS/2 1.0; usually 78 for OS/2 2.0). In Windows BMP, it equals the file size. | ||
| + | |||
| + | However, some OS/2 2.0 files have the field set to the file size, Windows-style. And some OS/2 1.0 files that are clearly from OS/2 systems do as well, making them completely identical to Windows BMP v2. | ||
| + | |||
| + | The difference is mostly irrelevant, though it could help to identify ''some'' OS/2 2.0 files as such. The Size field is redundant and unreliable, and is ignored by most BMP viewers. | ||
== Specifications == | == Specifications == | ||
Revision as of 01:55, 29 March 2014
IBM OS/2 BMP (also known as Presentation Manager Bitmap or PM Bitmap) is a family of raster graphics formats used on OS/2. It is closely related to Windows BMP.
The term OS/2 BMP can refer just to the "bitmap" formats (files with a signature of "BM"), or to the family of formats that also includes specialized icon and pointer formats.
There are two major versions of the bitmap format: OS/2 BMP 1.0, and OS/2 BMP 2.0. For details, refer to BMP.
For details about the icon format, see OS/2 Icon.
For details about the pointer format, see OS/2 Pointer.
Contents |
Format
All files begin with a 14-byte "file header", of which the first two bytes are an ASCII signature indicating the file type.
| Signature | Image type | Notes |
|---|---|---|
BA |
Bitmap Array | BA format is a kind of container format for one or more images in the other formats (often used with CI format). |
BM |
Bitmap | Refer to BMP for more information. |
CI |
Color Icon | Refer to OS/2 Icon. |
CP |
Color Pointer | Refer to OS/2 Pointer. |
IC |
Icon | Refer to OS/2 Icon. |
PT |
Pointer | Refer to OS/2 Pointer. |
OS/2 BMP vs. Windows BMP
OS/2 BMP 1.0 and Windows BMP v2 are sometimes said to be identical, but apparently that's not quite true. In OS/2 BMP formats, the "Size" field at offset 2 (variously named "cbSize", "FileSize", or "bfSize") is supposed to equal the size of the headers (always 26 for OS/2 1.0; usually 78 for OS/2 2.0). In Windows BMP, it equals the file size.
However, some OS/2 2.0 files have the field set to the file size, Windows-style. And some OS/2 1.0 files that are clearly from OS/2 systems do as well, making them completely identical to Windows BMP v2.
The difference is mostly irrelevant, though it could help to identify some OS/2 2.0 files as such. The Size field is redundant and unreliable, and is ignored by most BMP viewers.
Specifications
Sample files
BM (1.0)
Refer to BMP (Windows BMP v2).
BM (2.0)
- teamlog2.zip → TEAMcol.bmp, teamcol2.bmp
- test4os2v2.bmp
- CARDBMPS.ZIP - Most of the files are OS/2 BMP 2.0
- MAKMAN10.ZIP - Some of the files are files OS/2 BMP 2.0
- JUR_OS2.BMP
BA/BM
- CARDBMPS.ZIP → 9S.BMP, DIAMOND.BMP, HEART.BMP, MASK.BMP, SPADE.BMP
- MEMSZ128.ZIP → MEMSIZE.BMP
Links
- OS/2 Bitmap File Format Summary, from the Encyclopedia of Graphics File Formats
- Wikipedia page on the BMP file format has some info related to OS/2
