BMP file
From TrillWiki
.BMP is a bitmapped graphics format used internally by the Microsoft Windows graphics subsystem (GDI), and used commonly as a simple graphics file format on that platform.
- Full color
- Unlike a GIF file, which only has 256 colors, BMP supports 24-bit color (16 Million colors)
- Uncompressed*
- While the BMP format itself doesn't by default include compression, it can be encoded using run-length encoding, which is usually saved with an RLE extension. While the compression ratio is poorer than the other compressed formats for photos and the like, RLE file is decent in graphics with continuous color fields, such as would be used in a skin. RLE encoding is a lossless compression format. The one caveat to RLE encoding is that it only supports 4-bit or 8-bit images (i.e. 16 or 256 colors), so RLE files really don't give you any advantage over the other formats. Due to this perceived inferiority, many graphics editors will not give you the option to save as RLE, but Trillian does support it.
- No transparency**
- DIB / RLE does support an alpha channel saved as a separate file and windows XP has extended the BMP format to internally support 32-bit color (i.e. RGBA). However, to our knowledge, Trillian doesn't support this.
- No animation
- BMP has no animation layer. It just doesn't. Leave me alone, I'm busy.
| File type | Size | Notes |
| BMP | 44 KB | This is the original file. 256 colors, 195 X 220 = 42900 pixels. |
|---|---|---|
| RLE | 17 KB | This and GIF required the original image to be 256 colors for comparison |
| GIF | 12 KB | |
| PNG | 7 KB | |
| JP2 | 30 KB | Lossless JPEG-2000 |
| JPG | 9 KB | This does NOT return an identical image to the above formats Saved at IrfanView's '85% quality' |
[edit] See Also
- Windows bitmap on Wikipedia
- bitmap on FOLDOC
- BMP on Acronym Finder
- bitmap compression on MSDN
